shobha sondhia icar-dwr, jabalpur · leading to the blocking of the synthesis of the branch-chain...
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Herbicides residue hazards and their mitigation modalities
Shobha SondhiaICAR-DWR Jabalpur
Herbicide use Indian scenario
Insecticide 65
Herbicides16
Fungicide15
Other 4
Herbicide residues
According to WHO lsquoany substance or mixture of substances infood for man or animals resulting from the use of a pesticide andincludes any specified derivatives such as degradation andconversion products metabolites reaction products andimpurities that are considered to be of toxicological significancersquois defined as herbicidepesticide residue
Residues remaining on or in a crop commodity from a givenmethod timing and rate of herbicide application may vary withtrial site and climate and the limits of such variation areimportant to the establishment of maximum residue limits(MRLs)
Risk impact to freshwater algae due to mobility forherbicides applied in wet tropics sugarcane on a silt soil
type
Pesticide impact rating index (PIRI) software package (Kookana et al 2005)
Mobility risk Risk impact to freshwater algae
Herbicide residues a new threat to the environment if not handled properly
bull The widespread expansion of the industry on the great barrier reefcatchment area have resulted in a 3ndash7 fold increase in herbicide use (egatrazine 24-D and diuron)
bull Mixture of herbicide residues following river discharge events has thecapacity to produce cumulative chronic effects on sensitive species ofmarine plants and corals These effects may cause a change in thecommunity structure of mangrove seagrass and coral reef ecosystems
bull Most of the herbicide residues detected in the GBR lagoon (diuronatrazine hexazinone and ametryn) can be attributed to application insugar cane cultivation and exceeded the permissible limits
bull Tebuthiuron on the other hand is clearly linked to beef grazingmanagement practices
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide use Indian scenario
Insecticide 65
Herbicides16
Fungicide15
Other 4
Herbicide residues
According to WHO lsquoany substance or mixture of substances infood for man or animals resulting from the use of a pesticide andincludes any specified derivatives such as degradation andconversion products metabolites reaction products andimpurities that are considered to be of toxicological significancersquois defined as herbicidepesticide residue
Residues remaining on or in a crop commodity from a givenmethod timing and rate of herbicide application may vary withtrial site and climate and the limits of such variation areimportant to the establishment of maximum residue limits(MRLs)
Risk impact to freshwater algae due to mobility forherbicides applied in wet tropics sugarcane on a silt soil
type
Pesticide impact rating index (PIRI) software package (Kookana et al 2005)
Mobility risk Risk impact to freshwater algae
Herbicide residues a new threat to the environment if not handled properly
bull The widespread expansion of the industry on the great barrier reefcatchment area have resulted in a 3ndash7 fold increase in herbicide use (egatrazine 24-D and diuron)
bull Mixture of herbicide residues following river discharge events has thecapacity to produce cumulative chronic effects on sensitive species ofmarine plants and corals These effects may cause a change in thecommunity structure of mangrove seagrass and coral reef ecosystems
bull Most of the herbicide residues detected in the GBR lagoon (diuronatrazine hexazinone and ametryn) can be attributed to application insugar cane cultivation and exceeded the permissible limits
bull Tebuthiuron on the other hand is clearly linked to beef grazingmanagement practices
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide residues
According to WHO lsquoany substance or mixture of substances infood for man or animals resulting from the use of a pesticide andincludes any specified derivatives such as degradation andconversion products metabolites reaction products andimpurities that are considered to be of toxicological significancersquois defined as herbicidepesticide residue
Residues remaining on or in a crop commodity from a givenmethod timing and rate of herbicide application may vary withtrial site and climate and the limits of such variation areimportant to the establishment of maximum residue limits(MRLs)
Risk impact to freshwater algae due to mobility forherbicides applied in wet tropics sugarcane on a silt soil
type
Pesticide impact rating index (PIRI) software package (Kookana et al 2005)
Mobility risk Risk impact to freshwater algae
Herbicide residues a new threat to the environment if not handled properly
bull The widespread expansion of the industry on the great barrier reefcatchment area have resulted in a 3ndash7 fold increase in herbicide use (egatrazine 24-D and diuron)
bull Mixture of herbicide residues following river discharge events has thecapacity to produce cumulative chronic effects on sensitive species ofmarine plants and corals These effects may cause a change in thecommunity structure of mangrove seagrass and coral reef ecosystems
bull Most of the herbicide residues detected in the GBR lagoon (diuronatrazine hexazinone and ametryn) can be attributed to application insugar cane cultivation and exceeded the permissible limits
bull Tebuthiuron on the other hand is clearly linked to beef grazingmanagement practices
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Risk impact to freshwater algae due to mobility forherbicides applied in wet tropics sugarcane on a silt soil
type
Pesticide impact rating index (PIRI) software package (Kookana et al 2005)
Mobility risk Risk impact to freshwater algae
Herbicide residues a new threat to the environment if not handled properly
bull The widespread expansion of the industry on the great barrier reefcatchment area have resulted in a 3ndash7 fold increase in herbicide use (egatrazine 24-D and diuron)
bull Mixture of herbicide residues following river discharge events has thecapacity to produce cumulative chronic effects on sensitive species ofmarine plants and corals These effects may cause a change in thecommunity structure of mangrove seagrass and coral reef ecosystems
bull Most of the herbicide residues detected in the GBR lagoon (diuronatrazine hexazinone and ametryn) can be attributed to application insugar cane cultivation and exceeded the permissible limits
bull Tebuthiuron on the other hand is clearly linked to beef grazingmanagement practices
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide residues a new threat to the environment if not handled properly
bull The widespread expansion of the industry on the great barrier reefcatchment area have resulted in a 3ndash7 fold increase in herbicide use (egatrazine 24-D and diuron)
bull Mixture of herbicide residues following river discharge events has thecapacity to produce cumulative chronic effects on sensitive species ofmarine plants and corals These effects may cause a change in thecommunity structure of mangrove seagrass and coral reef ecosystems
bull Most of the herbicide residues detected in the GBR lagoon (diuronatrazine hexazinone and ametryn) can be attributed to application insugar cane cultivation and exceeded the permissible limits
bull Tebuthiuron on the other hand is clearly linked to beef grazingmanagement practices
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide residues worldwide
bull Herbicide residues are affecting seagrassessas a result ofrunoff from sugarcane industry
bull Seagrass is a taxonomic group of about 60 species worldwidelikely evolving from a single monocotyledonous floweringplant ancestor
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide residues in grapes and wines
bull Norflurazon oxyfluorfen oxadiazon or trifluralin-persistentherbicides commonly used for weed control in vineyards
bull Norflurazon was the most persist herbicide although therewere detectable residues of all the herbicides on both red andwhite grapes
bull The penetration of herbicides into the flesh of the grapes wasfound to be significantly greater for white grapes than for redgrapes
bull Small-lot winemaking experiments showed that norflurazonpersisted at levels close to the initial concentration throughvinification and into the finished wine (Ying and Williams2004)
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide residues in soil and plant parts at harvest
Herbicides Crop Dose
(gha)
Residues (μgg)
Soil Grains Straw
Butachlor Rice 1000 0005 0025-0002 0029-0006
Sulfosulfuron wheat 25 BDL 0010- BDL 0004- BDL
Metsulfuron-
methyl
Rice 4-4 BDL BDL 0002
Wheat 4-8 BDL BDL BDL
Isoproturon Wheat 1000 0006-0032 0035-0041 0065-0022
Oxyfluorfen Rice 150-250 BDL 0018 0106
Imazosulfuron Rice 30-40 BDL BDL BDL
50-60 BDL 0006-0009 0009-0039
Anilofos Rice ltMRL ltMRL ltMRL
Clodinafop Wheat 240 0021-BDL 0096-BDL BDL
Ref Sondhia 2005-2016
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of herbicides fishes
Anilofos
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
LD50 Vs herbicide myth
Interestingly many herbicides have high LD50 values have the similar or even higher ADI values as other extremely toxic insecticides and we considered lsquoHerbicidersquo as safe
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Pesticide LD50(mgkg) ADI(mgkg) NOEL(mgkg)
Acephate 846 0003 022
Alachlor 4790 00025 05
Aldrin 67 00001 047
Atrazine 3300 0005 05
Clodinafop-propargyl gt2276 0004 037
Cyhalofop-butyl 5000 0002 02
Diuron gt5000 0007 07
DDT 113 0002 02
Haloxyfop 337 00003 003
Glufosinate ammonium 2170 0007 067
Glyphosate 5000 03 30
Monocrotofos 116 00006 003
Paraquat 45-150 0004 045
Herbicide Vs other pesticides
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
MRL level and risk
Zone 4 LOAEL Exceeding MRL and totaldietary intake risk to human healthZone 3 NOAEL
Zone 2 ADI Exceeding MRL but below ADI safe for human health
Zone 1 ltMRL Compliance with MRL safe for human health
If lowest observed effect level can be seen it need to take immediate action
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Factor affecting Herbicide residues
bull Most residue problems can be associated with the use of longlived soil-residual herbicides
bull High level of chemicals remaining at the site into thefollowing growing season are refereed to as carryover whichresults in stunted or malformed plants or lack of seedlingemergence
bull Factors contributing to persistence involve misapplicationenvironmental condition soil texture organic matter contenttemperature rainfall moisture water holding capacity andpercolation rate
bull Dry weather for first month after application increase chances of carryover
bull High pH increase carryover of SUs triazine (gt7)
bull Low pH lt6 reduce microbial degradation of SU imidazolines
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicide Persistence in soil
(days)
Atrazine 45-90
Alachlor 60-80
2 4-D 45-90
Butachlor 100
Fluazifop p-butyl 30-90
Isoproturon 90-120
Metribuzin 20-100
Oxadiazon 56-125
Pyrazosulfuron-ethyl 35-60
Pretilachlor 30-60
Oxyfluorfen 60-80
Imazethapyr 90-240
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Herbicides Re-cropping restriction
Sulfonylureas Pea lentil
Imidazoline Soybean sunflower
24-D Tomato
Fluroxypyr Wheat barley oats rye corn flax
canola mustard lentils peas
Clopyralid Wheat barley oats rye corn flax
canola mustard lentils sugar beets
Metosulam Wheat lupins
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Sulfosulfuron is a systemic sulfonylurea (herbicide that is absorbed both by roots and foliage and is translocated in the xylem and phloem
It is an enzyme acetolactate synthase (ALS) Inhibits leading to the blocking of the synthesis of the branch-chain amino acids (valine leucine and isoleucine)
Molecular formula C16H18N6O7S2 Molecular mass 47049
Sulfosulfuron 1-(46-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonylimidazo[12-a]pyridine) sulfonyl]urea
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Residues of aminopyrimidine at 30-45 cm
DosageOccasion in days
0 5 10 20 30 50 100
T4 ND ND ND ND ND ND ND
T1 ND ND ND ND ND 0002 ND
T2 ND ND ND ND 0003 0005 0003
T3 ND ND ND ND 0008 0010 0005
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of sulfosulfuron residues at 150 days on maize pea barley and sorghum
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Sorghum Peas
Phytotoxicity of sulfosulfuron and its breakdown product in soil
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of sulfosulfuron residues in succeeding crop pea and lentil (Rabi)
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of sulfosulfuron on maize crop in Kharif(sandy loam soil)
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Maize under sulfosulfuron 25 g ai ha
Maize under sulfosulfuron 50 g ai ha
Maize under sulfosulfuron 100 g ai ha
Maize under control
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
bull Cultural methods
bull Bio-chemical processes
Residue mitigation measure
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Cultural methods
bull Herbicides drift may be eliminated largely by usingproper nozzle spraying techniques proper time ofapplication and is of correct formulation
bull Repeated application of the same herbicides in a monocrop sequence may cause accumulation of residues insoil which in turn will affect the sensitive crops
bull Choosing a herbicide with little or no carry-over given insoil and crop weather conditions will eliminate futurecrop injury problems
bull Early season application also assists in reducing thecarry-over potential to succeeding crops The longer theherbicide is exposed to breakdown factors such asmoisture and temperature the lower the risk of carry-over
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Decontamination methods under field conditions
Deep Ploughing -FYM at 10 ThaGreen manuring by Sesbania
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of Decontamination techniques on soil after 400 days (sorghum pea lentil and maize)
soi
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Adverse effect of sulfosulfuron on
plants amino acids
Detoxification of sulfosulfuron by
formation of sulfosulfuron-
dextrose conjugation
Toxicity of sulfosulfuron
Test plant Common Vetch (Vicia Sativa) and wheat
Remedy Dextrose at 05 and 10 kgha doses
Observation amino acid contents of weed and wheat plants
Sondhia et al 2015
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Ploughingcultivating the land
bull Carbamates thiocarbamates (thiobencarb triallate anddinitroaniline (oryzalin fluchloralin) are lost in the environmentby surface volatilization
bull Ploughing with disc plough or inter-cultivations reduce theherbicide toxicity
bull Tillage encourages herbicide decomposition indirectly throughincreased microbial and chemical breakdown
bull Applications of Addition of Organic matter (FYM) and greenmanuring not only increase the microbial population but alsoenhance the herbicides degradation at faster rate
bull A 50 tha of muck+peat and FYMapplication at 10 tha added to soil canalso eliminate triazines and SUrsquos residuesfrom soil
bull Planting cover crops increase soil organicmatter and biological activity 24
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
bull Antidotes or plant protectants are applied to the soilcrop seed or transplants to protect the crop fromherbicide injury The mode of action of antidotes maybe due to deactivation or adsorption of the herbicidepreventing its absorption and translocation by the cropeg 1 3-naphthalic anhydride (NA) and 2 2-dichloro-N N-diallyl acetamide can be used to minimize
bull Combining a non-residual herbicide with the lowestrecommended rate of a residual herbicide in a tank-mixture can reduce carry-over potential
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Toxicity prevention approachbull Activated carbon is very effective in deactivating residues of
non-ionic herbicides with low water solubility such astrifluralin bromacil benefin bensulide DCPA dichlobenilEPTC (Eptam) 2 4-D terbacil and chloroacetamidesulfonylureas etc
bull The use of 5 charcoal filter together with filter pads or withdiatomaceous earth was shown to be effective in removingmore than 96 herbicide residues (norflurazon) from thefinished wine
bull The efficiency of deactivation depends on the soilrsquos organicmatter and physical conditions the herbicidersquos activity and thecroprsquos sensitivity
bull The use of safeners and antidotes (13-naphthalic anhydride(NA) and 22-dichloro-NN-diallyl acetamide) along withherbicides protect crop from possible damage caused by theherbicides
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Addition of absorbents antidotes and safeners
bull Activated charcoal (or carbon) can reduce herbicidecontamination in specific areas and can also be used as a rootdip to protect transplants (tomatoes peppers strawberriesornamentals etc) from triazine or substituted urea herbicides
bull Activated charcoal has a high adsorptive capacity because of itsextremely large surface area which vary from 600-1200m2g
bull Activated charcoal may either be broadcasted or applied asnarrow band over the seed at the time of planting Herbicidesthat carbon can deactivate include trifluralin 2 4-Dchloroacetamide and sulfonylureas herbicides
bull The incorporation of 50 kgha of activated charcoal inactivatedcompletely chlorsulfuron applied at 125 and 250 kgha injuryfrom EPTC
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Use of safeners
Safner Herbicide Crop
Cloquintocet-mexyl Clodinafop-propargyl
wheat
Fenclorim Pretilachlor Rice
Furilazole Halosulfuron Cereals
Fenchlorazole-ethyl Fenoxaprop-ethyl Wheat
Safener works by reducing the ability of herbicides toreach and inhibit their target sites by interactingdirectly with the biochemical targets or receptors ofproteins of herbicide in the plants
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Tolerant crops cultivars and controlled mobility approach
bull Selection of tolerant varieties of cropbull Maize and sorghum for instances is a good candidate
for decontaminating a field containing triazine and SUrsquosherbicides
bull Pea and lentil can be used to detect sulfosulfuronresidues in soil
bull Leaching the herbicide by frequent irrigations is possibleespecially in case of water soluble herbicides In thiscase the herbicides are leached down to lower layersie beyond the reach of the crop roots
bull Heavy irrigation may leach a mobile herbicide beyondthe root zone of rotation crops
bull Continuous moist soils often result in more rapidbreakdown of herbicides due to creation of favourableconditions for microbial activity
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Use of non phytotoxic oil
bull Atrazine residual hazard could be reduced by mixing in non phytotoxic oil which would also enhance the weed killing potency and enhance the yield of maize and subsequent wheat with considerable reduction in the area affected in wheat
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Use of biocharbull The use of biochar could contribute to the increase of
pesticides sorption on soil decreasing its mobility andreducing the contamination risks of surface and groundwaters
bull The knowledge of biochar properties which depends on thefeedstock and pyrolysis conditions is vital
Biochar property
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Effect of biochar on herbicides sorption and efficacy
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
bull Vegetated ditch was effective for mitigation of mesotrione S-metolachlor and terbuthylazine after an extreme runoff Thebed part of the ditch was partially covered (10 of surface)by Phragmites australis Iris sp Scirpus sp Typha sp
bull Two other subsequent floods with uncontaminated waterwere applied 27 and 82 days later to evaluate herbicidesrelease
bull Ditch can immediately reduce runoff concentration ofherbicides by at least 50 even in extreme floodingconditions The half-distances were about 250 m
bull As a general rule a runoff of 1 mm from 5 ha is mitigated by99 in 100 m of vegetated ditch
Ref Otto et al (2015) PLoS One Vegetated Ditches for the Mitigation of Pesticides Runoff in the Po Valley
Vegetated ditch for herbicide mitigation
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Removal of herbicides by Vegetated Filter Strips
bull Vegetated filter strips (VFSs) or Vegetated buffersstrips (VBS) established at the down slope edge ofagricultural fields have long been recommended as amanagement practice to reduce sediment nutrientsand pesticides in surface runoff before it enters waterbodies
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Use of microbes bull Some soil microbes such as bacteria and fungi play an
important role in deactivating residues Aspergillusflavus and Aspergillus terricola rapidly degradedmetolachlor applied at 10 kgha up to 92 and 87 after 20 days in sterile and non-sterile soils respectively
bull Penicillium chrysogenum and Aspergillus sps were foundas potent pyrazosulfuron-ethyl iodosulfuron andpenoxsulam degrading fungi
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Degradation of iodosulfuron by soil fungi
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
bull Three major metabolites of iodosulfuron were detectedfrom soil two from rice plants were
1 2-amino-4-methoxy-6-methyl 135 triazine
2 2-amino-4-methoxy-6-methyl 135 triazine ureahydroxy-135 triazine
3 Methyl-4-iodo-2[3-(4-methoxy-6-methyl 135 triazine -2yl) uridosulfomyl] benzoate
bull Aspergillus niger was found able to degraded higherconcentration of iodosulfuron in soil
Degradation of iodosulfuron by soil fungi
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Use of polyacrylamide (PAM)
bull The use of polyacrylamide (PAM) and sediment basins have longbeen recognized as effective management practices for reducingpesticide and sediments in drainage water from irrigatedagriculture
bull It provides quick stabilization where vegetation has yet to beestablished
bull It promotes flocculation (reduces settling time) of smallestparticles increases soil pore volume and permeability thusdecreasing imperious cover
bull Less obtrusive than some conventional measures - doesnrsquotinterfere with construction machineryactivity
bull Convenient and easy to apply and store along with other soilamendments (fertilizer mulch etc) with conventional seedingmulching or irrigation equipment
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Disadvantages of PAM
bull PAM shall not be directly applied to water or allowed toenter a water body
bull PAM can not be used on a slope that flows into a waterbody without passing through a sediment trap or sedimentbasin
bull PAM will work when applied to saturated soil but is not aseffective as applications to dry or damp soil
bull Some PAMs are more toxic and carcinogenic than others
bull The specific PAM copolymer formulation must be anionicCationic PAM shall not be used in any application becauseof known aquatic toxicity problems
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Electrochemical deactivation
bull The electrochemical behaviour (DC and DP polarography) ofthe s-triazine herbicides prometrynedesmetryne andterbutryne on mercurye electrodes has been studied in theacidity range 225 M H2SO4 to pH 65 Two electronirreversible reduction processes were found complicatedwith adsorption At pH values higher than the protonation pKof the triazine ring this protonation reaction preceded thereduction processes
bull The product so obtained in the electro reduction of dilutesolutions of the above herbicides show a lower toxicologicaleffect than that of the original compounds (lower aromaticcharacter and cleavage of the ndashSCH3 group)
bull Electrochemical deactivation at pH 35 and at potentialsaround ndash110 V(vs the AgAgClKCl salt electrode) can be avalid method to deactivate these molecules
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Ozonation
bull Ozonation process at the output of200mghour at 015 kgcm2 for 15-30minutes removed some pesticides fromtomato up to 202 to 908 and can beutilized as post harvest technique forreduction of pesticides from vegetables
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Conclusionbull Herbicide must be applied in proper dose and time based
on the physico-chemical properties of herbicides soil waterand weather parameters to avoid residue problem
bull Sensitive crops should be avoided after using a soil residualherbicide
bull A field bioassay can be performed if suspecting a carryovereffect
bull A remedial measure should be advocated to thegrowersfarmers along with chemical weed control methodsto deal with high residues and to avoid any carryover effect
bull Improved formulations will be needed to reduce off-targetdeposition improve retention on target and enhanceuptake and translocation
Thank you
Thank you