chapter 5 protecting the environment

Chapter 1. Integrated Pest Management109

Chapter 5 Protecting the EnvironmentAir, water, and land are interconnected, and pesticides applied to reach target organisms also may reach fish, wildlife, plants, livestock, beneficial insects, and nearby people. This Chapter describes potential unintended effects of pesticides on the environment, pesticide movement in the environment, and successful strategies to protect the environment when applying pesticides.

Improving water quality and habitat is a priority among Minnesotans, as evidenced by the passing of the Clean Water, Land and Legacy amendment to the state constitution in 2008. Photo: Natural Resources Conservation Service (NRCS)

Chapter 5. Protecting the Environment

PRIVATE PESTICIDE APPLICATOR TRAINING MANUAL 19th Edition110

Notes Page


Section 1: The Pesticide Applicator’s EnvironmentEnvironmental protection laws and pesticide label directions are designed to prevent health and environmental problems caused by pesticides. In addition to knowing the law and following label directions, pesticide applicators should understand what can happen when pesticides applied to eliminate targeted pests end up in places these chemicals don’t belong. This Section discusses the range of “environments”—natural and manmade—that applicators encounter, and how they can be adversely affected by pesticides.

Learning Objectives:

1. Give an example of a situation in which pesticides have unintended consequences on air, water, or soil.

2. Discuss pesticide characteristics that affect the pesticide’s environmental fate.

3. Discuss environmental factors that can affect pesticides’ fate.4. Identify three kinds of “sensitive sites” that may be harmed by a

pesticide application.

Terms to Know:

w Adsorptionw Biomagnificationw Break-down productsw Driftw Food chainw Half-lifew Persistencew Solubilityw Temperature inversionw Vapor pressurew Volatility



Pesticide Use and the Environment

Pesticide applications cannot be safely undertaken without an under-standing of the interconnections among air, water, land, and the life they support. By understanding these environmental connections, pesticide applicators can better manage target pests while minimizing harm to the environment.

AirWhen pesticides are applied, they may be carried off-site in the air as spray droplets, vapors, solid particles, or even treated soil particles. The physical movement of pesticide spray droplets through the air, at the time of or soon after the pesticide application, to any site other than the intended site is known as pesticide drift. Pesticides applied in windy or dead calm conditions (during a temperature inversion) can move off-site and harm humans, animals, and the environment.

WaterPesticides are monitored in lakes, rivers, streams, groundwater, and rain by the Minnesota Department of Agriculture’s water quality program. The majority of these detections are at very low levels. However, a few pesticides have been detected at levels approaching or exceeding water quality benchmarks set for protection of humans or aquatic organisms.

Soybean aphids are a target organism for chlorpyrifos pesticides. Photo: University of Minnesota

Brisk Wind, Unintended ConsequencesChlorpyrifos pesticides are used to control soybean aphids and spider mites on soybeans. In August 2009, chlorpyrifos was being applied to a central Minnesota soybean field, despite wind speeds of 9-15 mph, gusting up to 17-23 mph. The label specifically prohibited application in winds in excess of 10 miles per hour.

The insecticide drifted onto a residential property. Apple trees and vegetables on the property were sampled, and chlorpyrifos contamination was documented. The Minnesota Department of Agriculture (MDA) cited application violations: the label prohibited application when wind speed was greater than 10 mph, there was off-site drift and damage (contamination) of the apple trees and vegetables. MDA issued a financial penalty.

By applying pesticides when the weather is consistent with label directions, off-site drift can be minimized.


As pesticides move through the ground, microorganisms in the soil can break down the pesticide into other chemicals. Pesticides can also be broken down by sunlight, naturally occurring chemicals in the soil, and by plants. Most of these break-down products are less toxic to the environment than the original pesticide, but some can be more toxic.

LandLand consists of different types of soil (such as sand, clay, or silt) often layered on top of one another, underlying or exposed rock formations, and groundwater. Pesticides properly applied to the land surface as directed by the label usually stay there until they break down into inactive compounds.

Problems arise when surface runoff carries pesticides into lakes, streams, and wetlands; or water percolating through the soil carries pesticides down to groundwater. Pesticides with a long effective half-life break down slowly and may move to a location where they could harm plants, insects, animals, or bacteria.

Pesticide Fate in the EnvironmentSeveral processes affect the fate of pesticides in the environment. These include the way pesticides move in air, water, or soil after they are applied (transportation) and how they change after interacting with the soil, plants, or sunlight (transformation).

Among the ways that pesticides can be transported are:w Spray drift – during application, pesticides in spray droplets can

be shifted by the wind from the location where they were applied to another location.

Harvested Ditch Hay, Unintended ConsequencesA newly planted soybean field in the Lamberton area showed severe signs of herbicide damage. There had been no recent application of a broadleaf herbicide in that field, but manure had been applied in the spring. Tracing back, the manure was from horses that were fed ditch hay treated with picloram, a broadleaf herbicide used in rights-of-way.

Further investigation revealed harvest restrictions on the picloram product label. The label warns that if the harvest and grazing restrictions are not followed, the product may carry through to the manure and urine of animals fed picloram-treated plants. Picloram in the manure caused the soybean damage, which occurred because the label was not followed.

Always follow label grazing and harvest restrictions for herbicides that carry over into manure and urine.

Herbicides move from ditch hay to horse manure to a struggling soybean crop. Photo: NRCS



w Volatilization – pesticides can evaporate into the air and then the vapors may move on the wind.

w Runoff – pesticides can run off the land during rainfall, snowmelt, or irrigation.

w Leaching – pesticides can percolate through the soil into groundwater.

w Adsorption – pesticides can attach to soil and then move when soil is eroded by water or wind.

Transformation often involves the process of decomposition, when the original pesticide chemistry is transformed into a different, usually less complex, chemistry. As the break-down process progresses, the original pesticide disappears from the environment and is replaced by a series of break-down products, also called degradates. Pesticides can be transformed by:

w Plant uptake – plants can take up pesticides from the soil.w Photodecomposition – sunlight can break down pesticides.w Microbial decomposition – microorganisms in the soil can break

down pesticides into different chemical compounds.w Chemical degradation – over time, the soil’s chemistry can break down or change as bonds between molecules creating new

compounds.

Pesticide Properties That Affect Its Environmental FatePesticides’ chemical properties affect not only how effective they are, but also how they may move, persist, or break down in the environment.

Fate of pesticides in the environment. Adapted from the University of Illinois General Standards manual.

Breakdown of pesticides in the environmentAdapted from OSU Pesticides and Groundwater Contamination

Soil surface

Evaporation/Volatilization

Percolation/Leaching

Plant

Drift

uptake (absorption)Degradation

Degradation

Pesticidespray

Root zone

Water table

Groundwater

Surface water

nPrecipitatio

Surface runoff / erosion

degradationPhoto

Runoff


In other words, a pesticide’s specific properties affect its fate in the environment.

Pesticides that are volatile (evaporate readily at normal temperatures and pressures) are more likely to end up drifting to non-target areas.

Pesticides that have high solubility (the amount of a substance that will dissolve in a given amount of another substance, such as water, at a specified temperature and pressure) are more likely to end up in surface water. Highly soluble pesticides can mix as easily with rain as with the water used to dilute them to the appropriate application strength. Pesticides with high solubility also percolate into groundwater more rapidly than less soluble compounds.

Pesticides with high adsorption (that adhere in an extremely thin layer of molecules to the surfaces of soil or sediment particles) stick with the soil and stay in the environment longer.

Pesticides with a long soil half-life (the time required for half the amount of a substance introduced into a living system or ecosystem to be eliminated or disintegrated by natural processes) stay in the soil long after one or many treatments. Over time the pesticide concentration can actually build up in the soil.

Environmental Factors that Affect Pesticide FateWeather conditions have a major impact on pesticide fate. Rain, snowmelt, wind, humidity, temperature, sunlight, and temperature inversion all influence how pesticides are transported or transformed.

w Temperature inversions occur when the layer of air at ground level is colder than air higher up—the opposite of normal air temperatures. Inversions are very stable and create “dead calm.” Spray droplets from pesticides applied during inversions can stay in a concentrated cloud and move slowly toward sensitive plants and animals.

w Temperature increases make pesticides more volatile and may cause pesticides to move as a vapor to non-target sites and harm sensitive plants and animals. That is why some pesticide labels restrict application over a certain temperature.

Soil properties can influence how quickly chemical pesticides break down or move from the application location.

w Organic matter and clay particles in the soil are good at tying up (adsorbing) pesticides to their surfaces so the pesticide is no longer available in the soil. This is why some pesticides labels have higher application rates on soils high in organic matter or clay: to ensure effectiveness. When adsorbed to the surface of organic matter and clay particles, pesticides are prevented from moving to contaminate groundwater or surface water. Organic matter in soils also contains nutrients that nourish micro-organisms that naturally break down pesticides.

Note:Information about a pesticide’s soil half-life is often found in the Materials Data Safety Sheet (MSDS) for the product.

Breakdown of pesticides in the environmentAdapted from OSU Pesticides and Groundwater Contamination



w Soil texture and porosity also influence pesticide fate. Soils that are “tight,” such as those with lots of clay, have the benefit of preventing leaching, and so pesticides are not likely to reach groundwater. But such soils also allow for greater pesticide volatilization and surface runoff. Water moves rapidly through soils that are “coarse textured,” such as sandy or gravelly soil, increasing the chance of pesticides leaching to groundwater, but preventing surface runoff.

Finally, a soil that is steeply sloped allows dissolved pesticides to run off more rapidly than soils on flat or gently sloping lands.

The diagram below shows the breakdown of pesticides in the environment.

Pesticide Impacts on EcosystemsAn ecosystem is formed by the interaction of a community of organisms with their environment. When a pesticide is introduced, it can disrupt an ecosystem in a number of ways:

w It repels, controls, or kills the target pest The target pest, however, may be food for another organism. If the target pest is the major food source for a local bird species, the unintended outcome of killing the pest may be reducing the bird population.

Photodegradation

Chemical degradationMicrobial degradation

Chemical

degradation

(hydrolysis)

Breakdown of pesticides in the environment.National Pesticide Applicator Certification Core Manual. Adapted from OSU Pesticides and Groundwater Contamination.


Biomagnification in the food chain. Adapted from Penn. State Pesticide Education Manual.


DDT Concentration(parts per million)

w A pesticide that effectively kills a target organism may also effectively kill a beneficial species. Insecticides that kill wasps in a barn, for example, may also kill a hive of bees needed to pollinate fruit trees.

w Pesticides can accumulate through the food chain. As multiple small organisms are eaten by larger ones, pesticides found in the smaller organisms can build up in the tissues of the larger one. Biomagnification is a process whereby some organisms accumulate chemical residues in higher concentrations than those found in the organisms they consume.

BiomagnificationinLoons:UnintendedConsequencesCommon loons were studied to assess the biomagnification of persistent contaminants in lake ecosystems in Atlantic Canada. Forty-two breeding adults and 20 juvenile loons were captured in August 1995–1997 on lakes in New Brunswick and Nova Scotia. Plasma samples from adult loons were analyzed for PCB and organochlorine pesticides. Loons from one of the four sites had higher levels of PCBs, DDE, oxychlordane, trans-nonachlor, mirex, and hexachlorobenzene. The higher pesticide levels in the loons are attributed to the biomagnification of these pesticides found in their food supply.

Biomagnification is known to occur in Minnesota’s state bird, the Common Loon. Photo: National Parks Service


Sensitive SitesPesticide applicators exercise caution at any treatment location, but certain sensitive sites require greater planning and care. As the name indicates, sensitive sites are more susceptible to negative side effects that pesticides may have. Sensitive sites include:

w Areas producing organic crops or livestock. Products certified as “organic” are required to be grown free from most man-made pesticides for three or more years. Applying a pesticide not approved for organic production that ends up in the soil, water, or groundwater of an organic operation could have major economic and legal consequences.

w Lawns and gardens. Drift minimization is especially important here. Children and pets play on lawns. People of all ages and states of health eat food grown in gardens.

w Lakes, rivers, and wetlands. Many pesticides are toxic to fish and other aquatic organisms, including aquatic plants that form the base of the food chain. Minimize drift, leaching, and runoff.

w Parks and protected natural areas. Parks and natural areas contain high-value environmental resources, including threatened or endangered species. It is illegal to harm an endangered or threatened species, or to destroy or modify its critical habitat, when using a pesticide. Protect people in these areas, too, by observing safe application methods.

w Drinking water supplies. We all need safe drinking water. Applicators should know if a treatment site has any wells or is within a wellhead protection area (area around a well from which drinking water is drawn). Most at risk are shallow wells, abandoned or broken wells that may be hidden, and wells located in very permeable soil.

w Municipal drinking water well fields. Location and depth of municipal drinking water wells is an important consideration. Check with the local municipal water supplier if there is any possibility that the treatment site may be within a wellhead protection area. This is not always easy to determine without consulting the municipal water supplier.

w Waste management areas. Bacteria play an essential role in breaking down wastes in compost and manure treatment facilities, and pesticides can interfere with or kill beneficial bacteria. In addition, finished compost and re-applied manure are both recycled into the food supply.

w Air intake systems. Airborne pesticides that drift into an air intake system can be rapidly distributed throughout a building.

w Daycares, schools, senior facilities, or health-care facilities. These sensitive sites are likely to house children, the elderly, or people with health issues, all of whom may be more sensitive to pesticides than healthy adults.

Parks and protected natural areas, such as Aquatic Management Areas (AMAs) and Sensitive Natural Areas (SNAs) contain high value species and ecosystems. Photo: NRCS


The applicator who is aware of the potential harm to living things that depend on clean air, water, and land can take steps to minimize any unintended effects of pesticides. The next Section describes strategies to help the pesticide applicator to protect the environment.

Section 2: Preventing Impacts of Pesticides on the EnvironmentPesticides that move from a treatment site to nearby air, water, or land can have unintended adverse effects on living things. Applicators can prevent harm to the environment by understanding how pesticides move from treatment sites to locations where they might cause environmental damage or harm.

Learning Objectives:1. Name five pesticides that have best management practices (BMPs)

developed for them by the Minnesota Department of Agriculture.2. Know who is legally liable for damage caused by pesticide drift.3. Name at least three of the factors that affect the droplet size of an

applied pesticide.4. Describe what benefits a vegetative buffer zone has in preventing

impacts of pesticides on non-target sites and organisms.

Terms to Know:w Application setbackw Best management practices (BMPs)w Karst geologyw Non-point source pollutionw Vegetative buffer



Protecting Water The Minnesota Department of Agriculture (MDA) and other agencies monitoring water quality have sometimes found pesticides in Minnesota’s surface and groundwater. By preventing “point source” water contamination that comes from places where pesticides are stored, mixed, or loaded into application equipment, applicators can protect our water resources. Preventing “non-point source” contamination that occurs when a pesticide runs off the soil surface or leaches through the soil profile, is just as important. Pesticide applicators can do many things to protect Minnesota’s waters. Minnesota’s Pesticide Management Plan spells out pollution prevention strategies that applicators can follow.

Minnesota’s Pesticide Management PlanMinnesota law requires the state to have a Pesticide Management Plan for the protection of groundwater and surface water. This plan calls for monitoring for pesticides and, if they are found, developing appropriate response plans. Most importantly, this plan focuses on preventing pesticides—and their break-down products—from reaching Minnesota’s water resources.

To reach this goal, the Pesticide Management Plan requires the MDA to develop Best Management Practices (BMPs). BMPs are practical, research-based ways for users of pesticides to prevent or minimize surface water and groundwater contamination. BMPs reduce water contamination by helping applicators properly:

w Store pesticides;w Transport pesticides;w Mix and load pesticides into application equipment;w Apply pesticides;w Manage pesticide waste; andw Develop incident response plans for pesticide leaks, spills,

or accidents.

Minnesota ranks number one in fishing licenses per capita, and the state places a high priority on clean rivers, lakes, and streams.


The Pesticide Management Plan established a process for the MDA to develop water-quality BMPs for pesticides commonly detected in groundwater or present at levels of concern in surface water. These BMPs will reduce water contamination that may result from the normal, legal use of pesticides. The BMPs are voluntary unless they reference label requirements. As always, read and follow label directions.

Minnesota currently has core water quality BMPs for all agricultural herbicides and specific BMPs for these five herbicides:

w Acetochlor,w Alachlor,w Atrazine, w Metolachlor, andw Metribuzin.

Pesticide applicators using agricultural herbicides should understand and implement water quality BMPs whenever possible to protect water resources and avoid additional requirements. Under the Pesticide Management Plan, Minnesota may impose pesticide-use restrictions if voluntary BMPs do not keep water contamination from a specific pesticide within water quality standards. To learn more about the Pesticide Management Plan or to review current BMPs, see the MDA’s pesticide management website information at www.mda.state.mn.us/pesticides. Find fact sheets describing water quality BMPs for herbicides on the MDA website at www.mda.state.mn.us/herbicidebmps. The MDA has developed an electronic distribution list (e-mail listserv) to communicate via e-mail about MDA activity related to pesticide non-point source water quality issues. To subscribe to the MDA Pesticide Non-Point Source electronic distribution list, go to the following website and follow the instructions for signing up to receive e-mail updates: http://webmail.mnet.state.mn.us/mailman/listinfo/mda-pesticide-non-point-source.

Surface Water Surface water includes the lakes, rivers, streams, ponds, ditches, and wetlands with which Minnesota is richly endowed. Following application, pesticides can move into surface water in several ways, including through:

w Surface water runoff. Runoff from hard surfaces, such as pavement and compacted soil, travels faster and transports more pesticide than runoff from surfaces that absorb water.

w Tile drainage. Tile systems and their surface tile intakes can transport pesticides from the land to surface waters.



w Air deposition. Pesticides can enter surface water as spray drift, from movement of volatized pesticides or from the deposition of airborne dust.

Pesticides that have high solubility are more likely to end up in surface water and groundwater because, once they are dissolved in water, they can go wherever water goes.

Application Setbacks and Vegetative Filter Strips

Two recommended BMPs for protecting surface water are application setbacks (also called application buffer zones) and vegetative filter strips (also called vegetative buffer strips).

An application setback is created when the pesticide applicator leaves distance between an area treated with a pesticide and an associated sensitive area, such as surface water in need of protection. Application setbacks reduce the possibility of a pesticide drifting into the sensitive area during application or entering the sensitive area after application in field runoff.

A vegetative buffer or filter strip is an area of permanent close-growing vegetation over which field runoff passes before entering surface water. Vegetative filter strips trap pesticides running off treated locations before they reach surface water. Filter strips often are located on the field edge adjacent to water bodies, but can also be located within the field in the form of a grassed waterway.

Some product labels require mandatory application setbacks or vegetative filter strips to protect water quality.

Grassed waterways trap pesticides and prevent runoff to surface water. Photo: NRCS


Examples of pesticides with labels requiring mandatory application setbacks are the herbicide atrazine and the pyrethroid family of insecticides. At this writing, atrazine requires a 66-foot application setback from points where field runoff enters streams or rivers and a 200-foot application setback from the water edge of lakes. Pyrethroid insecticides currently require a 25-foot application setback from the water edge of aquatic habitats if ground applied and a 150-foot application setback if aerially applied.

In addition to an application setback, pyrethroid insecticides require a 10-foot-wide vegetative filter strip between the field edge and downgradient aquatic habitats. Fact sheets to assist applicators with interpreting these requirements on the atrazine and pyrethroid product labels can be found on the MDA’s website. Application setbacks and vegetative filter strips may be required on the labels of other pesticide products. Read pesticide labels carefully to see whether these practices are required.

Soil and water conservation district staff can be consulted for assistance on the design and installation of vegetative filter strips, grassed waterways, and other conservation practices that protect surface water.


Fi e l d Runoff

Stre

amo

rR

iver

Berm

Minnesota Department of Agriculture graphic


GroundwaterSeventy percent of Minnesota’s drinking water is obtained from ground-water. Pesticides can move into groundwater in a number of ways:

w With rain water, as it leaches through pesticide-treated soil. w Through improperly constructed or abandoned wells that act like a

conduit between surface water and groundwater.

As noted in the previous section, pesticides with high solubility, low adsorption, or a long half-life have a greater potential to move into groundwater. Pesticide applicators can avoid groundwater contamination by knowing site conditions in advance, including:

w Permeability of soil. Water leaches more rapidly through a “coarse-textured” soil (such as sandy soil) than through a “tight” soil (such as clay-like soil). Information about soil permeability can be obtained from the local soil and water conservation district office.

w Depth to groundwater. The greater the depth to groundwater, the more protected the groundwater is from pesticides leaching through soil. Some product labels have application restrictions based on depth to groundwater. The Minnesota Department of Agriculture’s voluntary water quality BMPs recommend specific rates of application on certain soil types to help protect groundwater.

Karst Geology: Sensitive Groundwater Resources in Southeastern Minnesota

Karst geology is one of Minnesota’s most interesting and well-studied environmental features. Karst forms on soluble rock (frequently, but not always, limestone) that is worn down by water over time. Karst is characterized by caves, sinkholes, a lack of surface drainage, and other climatically controlled features. These characteristics make southeastern Minnesota water resources challenging to protect. Chemicals, such as pesticides, used on the landscape infiltrate rapidly into groundwater and then migrate, reappearing at unexpected times and in unexpected locations. Know your farm’s soils and geology. Select pesticides and application methods that prevent ground- and surface water contamination.


Preventing Drift

The EPA defines pesticide spray drift as the physical movement of a pesticide through the air, at the time of or soon after the pesticide application, to any site other than the intended site (often referred to as an “off-target” site). Pesticide drift is not a new problem. However, with increasing acreage planted to herbicide-resistant crops and a shift to more post-emergence spraying, the potential for off-target drift damage has increased. Drift can transport either particles or vapors through the air.

Particle drift occurs at the time of application, as small droplets and particles of the spray solution suspended in air move to an off-target location. Recent research has shown that all pesticides have the potential to move via particle drift, and that particle drift is much more common than vapor drift.

Vapor drift occurs when the pesticide changes from a liquid to a vapor, or gaseous form, and then moves away from the treated area. Vapor drift can occur both during and soon after application. Vapor drift is more common with certain pesticides that are volatile (evaporate more readily). It is possible with some pesticides that the chemical turns into a vapor after it has been applied—sometimes even hours after application.

Distance Spray Drift Can Travel (3 mph Wind)

Droplet Size Diameter (in microns)

Time to Fall 10 Feet

Travel Distance

Fog 5 66 minutes 3 milesVery Fine 20 4.2 minutes 1,100 feetFine 100 10 seconds 44 feetMedium 240 6 seconds 28 feetCoarse 400 2 seconds 8.5 feetFine Rain 1,000 1 second 4.7 feet

Source: Herbicide spray drift, North Dakota State University Extension.

Damage from pesticide drift can be significant. Drift to adjacent fields can cause crop destruction or produce crops with pesticide residues so high that they can’t be used or sold. Even long-established trees and ornamental plants can be harmed. Fish and wildlife kills, including destruction of desirable honeybees, can result from minimal off-target movement of some pesticides, particularly insecticides.

Pesticide labels and laws are clear that off-target drift is illegal:w State law specifies that pesticide applications must be performed

in a manner that does not endanger humans or damage agricultural products, food, livestock, fish, or wildlife.

w State and federal laws require that pesticides must be applied in a manner consistent with labeling. Since pesticide product labels



almost always contain language that says “Do Not Allow This Product to Drift,” or words to that effect, drift is a violation of state law. Labels often give recommendations for minimizing pesticide drift.

w Evidence that drift occurred is a violation of federal pesticide control law.

w Minnesota has a strict liability legal standard for enforcement of cases involving pesticide drift; if drift occurs, the applicator is responsible. No proof of negligence, carelessness, or intent is necessary for the MDA to bring an enforcement action against the applicator.

w The applicator is responsible for pesticide drift damage.

The bottom line is that whether or not damage results, pesticide drift is illegal and is not tolerated in the regulatory or agricultural community. Drift also has non-financial consequences, and an incident of off-target drift can incur hostility from neighbors, businesses, and other land owners in the area.

Damage and concerns about pesticide drift are the most common types of complaints reported to the MDA (for information about complaints, see http://www.mda.state.mn.us/chemicals/pesticides/complaints.aspx). Pesticide drift issues continue to be a national priority for the U.S. Environmental Protection Agency, state departments of agriculture, farm groups, industry organizations, advocacy groups, and the Extension Service. Many complaints of pesticide drift are filed by farmers who are frustrated and angered by the repeated and damaging drift from neighboring farms. If farmers have or seek certification as an organic producer, drift can destroy years of work and an entire crop.

Development of urban/suburban communities in formerly rural areas has increased the potential for complaints about suspected damage. In urban/suburban communities where residents aren’t familiar with pesticide use for agricultural settings, residents often consider pesticide drift a threatening “chemical trespass,” no matter what the actual risk or damage may be.

Although drift is by far the most common way for pesticides to move to off-target locations, other ways that pesticides move through air include volatilization and windblown contaminated soil particles.

Drift PreventionSpray droplet size is the single biggest factor in determining whether a pesticide will drift. Small droplets take longer to fall and can be carried further by wind currents. Medium or large droplets fall faster and travel much shorter distances. New technologies, such as drift-reduction nozzles or spray additives that reduce drift, can be helpful in keeping pesticides on the target site.


Droplet size is a function of:w Nozzle size. When selecting nozzles, consult the manufacturer’s

information on average droplet size under various pressures. If possible, avoid nozzles that produce fine, very fine, or fog droplets —those 200 microns or less—at the pressure you plan to use.

w Pressure. Higher application pressures create more small droplets that are likely to drift.

w Boom heights. Calibrate application equipment to apply pesticides at a lower boom height to decrease the distance that droplets travel to reach the ground.

w Temperature and relative humidity. As the air temperature increases and humidity decreases, droplets evaporate, become smaller and lighter, and travel further.

After droplet size, wind speed and direction are the most important factors affecting pesticide drift. Recording wind speed and direction (from which the wind is blowing) for each application will help private applicators document correct application if a drift complaint is filed.

Avoid spraying any pesticides when winds are greater than 10 mph. Know the wind speed and direction at the time of application. Conditions reported by local weather services vary greatly from conditions at the application site. Measuring wind and temperature at the time and place of application is best. New rigs may come with wind and temperature gauges. Otherwise, a simple hand-held gauge is good.

Note:If you need to hire a commercial pesticide applicator, make sure that the applicator follows label directions, too. Commercial applicators are required to give you a copy of the application record, which must include wind speed and direction at the time of application.

Symbol

VF

Category

Very Fine

Code

Red

Approx.

VMD2

<100

Comparative Size

Point of Needle

(25 microns)

Atomization

Fog

F

1American Society of Agricultural Engineers.2Volume Median Diameter.

Fine Orange 100–175 Human Hair

(100 microns)

Fine Mist

Sewing Thread

(150 microns)

Fine Drizzle

Staple

(420 microns)

Light Rain

#2 Pencil Lead

(2000 microns)

Thunderstorm

Relative Size

M Medium Yellow 175–250

C Coarse Blue 250–375

VC Very

Coarse

Green 375–450

EC Extremely

Coarse

White >450

ASAE1 Standard Comparative Size


Adapted from Bob Wolf, Wolf Consulting & Research, LLC


Although dead-calm conditions may seem ideal for pesticide application, they may signal a temperature inversion. An inversion occurs when the air close to the ground is colder than air higher up in the sky and air doesn’t mix. Under inversions, the winds are very light to dead calm and variable in direction. Pesticide sprays form small droplets (fines) that do not fall out under inversion conditions. The pesticide fines can rise up until they hit the warmer air layer. The pesticide cloud may drift horizontally as a concentrated cloud for long distances. For this reason, do not apply pesticides during temperature inversions.

As stated earlier, be especially careful near sensitive sites. If the wind is blowing towards sensitive sites, even at low speeds, damage from drift may occur. The best recommendation when applying pesticides near sensitive sites is to spray when the wind is gentle (3-10 mph), steady, and blowing away from high-risk areas. Sensitive sites can be protected by pesticide applicators using application setbacks, also referred to as application buffer zones—areas in which no pesticide is applied. If drift occurs despite every effort on the applicator’s part, it will fall on the buffer zone rather than the sensitive area adjoining the target site.

To prevent drift, responsible and knowledgeable applicators set up and calibrate application equipment with drift-reduction nozzles, lower pressure settings, and lower boom heights to minimize drift. They check wind speed, temperature, humidity, and conditions that signal inversions before application. They establish buffers around sensitive sites or resources to ensure that pesticides will stay on site and on target.

This farmer established a buffer zone between his fields and nearby sensitive water resources. Photo: NRCS


Section 3: Protected SpeciesAvoiding damage to non-target plants and animals is always the responsibility of pesticide applicators, but that responsibility is all the more critical when endangered or threatened species are concerned. In this Section, pesticide applicators will learn about the federal Endangered Species Act, Minnesota’s endangered species, and methods to check in advance whether these species are within range of an area where pesticide application is planned.

Learning Objectives:

1. Identify the three categories of endangered species covered in the federal Endangered Species Act.

2. How does Minnesota’s endangered species statute differ from the federal law?

3. Describe how you would find out what protected species are located in the area in which you plan to apply pesticides.

Terms to Know:

w Candidate speciesw Endangered speciesw Threatened species

Prairie bush clover, a threatened species, is found in agricultural areas of the state. Photo: DNR



Endangered Species ActCongress passed the federal Endangered Species Act in 1973 to stop further extinction of plants and animals. The act defines endangered species as a plant or animal in danger of extinction, and a threatened species as a plant or animal likely to become endangered within the foreseeable future. Candidate species—those that are in the process of being designated as threatened or endangered—are also listed.

It is illegal under the Endangered Species Act to kill or harm an endangered or threatened species. It is also illegal to destroy or modify critical habitats on which they depend. Pesticide applicators should delay or forgo pesticide application if protection of endangered or threatened species cannot be ensured. There is no legal excuse for harming endangered or threatened species or their crucial habitats with a pesticide. The U.S. Fish and Wildlife Service (FWS) keeps the federal list of endangered, threatened, and candidate species (see the table on page 131).

Minnesota Endangered Species Statute and RulesMinnesota also has an endangered species statute. The Minnesota Department of Natural Resources (DNR) implements the Minnesota Endangered Species Statute and related state rules. Minnesota has a separate protection program and its own listings of endangered and threatened species, as well as species of special concern.

Minnesota’s Endangered Species Statute prohibits killing, harming, importing, transporting, or selling any part of a member of a species listed by the state as being endangered or threatened. For more information, see the DNR Web sites on endangered, threatened, and special concern species (www.dnr.state.mn.us/ets/index.html and www.dnr.state.mn.us/rsg/laws.html).

Through the work of the FWS, DNR, and MDA, landowners in Minnesota generally know when an endangered, threatened, or candidate species is living on their property. Pesticide applicators should check with landowners about the presence of protected species before applying pesticides.


Federally Listed Endangered, Threatened and Candidate Species in Minnesota

Plants

Leedy’s roseroot (Sedum integrifolium ssp. leedyi)

Threatened Cool, wet groundwater-fed limestone cliffs

Fillmore, Olmsted

Minnesota dwarf trout lily (Erythronium propullans)

Endangered North-facing slopes and floodplains in deciduous forest

Dakota, Goodhue, Rice, Steele

Prairie bush clover (Lespedeza leptostachya) Threatened Native prairie on well-drained soils

Brown, Cottonwood, Dakota, Dodge, Goodhue, Jackson, Martin, Mower, Olmsted, Redwood, Renville, Rice, Rock

Western prairie fringed orchid (Platanthera praeclara)

Threatened Wet prairies and sedge meadows

Clay, Kittson, Lincoln, Mower, Nobles, Norman, Pennington, Pipestone, Polk, Red Lake, Rock

Mammals

Canada lynx (Lynx canadensis) Threatened Northern forested areas Aitkin, Beltrami, Carlton, Cass, Clearwater, Cook, Itasca, Koochiching, Lake, Lake of the Woods, Marshall, Pine, Roseau, St. Louis

Gray wolf (Canis lupus) Threatened Northern forested areas Northeastern portion of the state

Birds

Piping plover (Charadrius melodus) Endangered Sandy beaches and islands

Lake of the Woods, St. Louis

Reptiles

Eastern massasauga (Sistrurus catenatus catenatus)

Candidate Wetlands and nearby upland areas

Houston, Wabasha, Winona

Mussels

Higgins eye (Lampsilis Higginsi) Endangered Large rivers Lower St. Croix RiverSheepnose (Plethobasus cyphyus) Candidate Large rivers Lower St. Croix River

Spectaclecase (Cumberlandia monodonta) Candidate Large rivers Main channel St. Croix RiverWinged mapleleaf (Quadrula fragosa) Endangered Medium rivers and

streams, large riversSt. Croix River south of Taylor’s Falls

Insects

Dakota skipper (Hesperia dacotae) Candidate Upland prairie Western boundary of the stateKarner blue butterfly(Lycaedes melissa samuelus)

Endangered Sandy barrens and savannas

Anoka, Winona

Fish

Topeka shiner (Notropis topeka) Endangered Small rivers and streams

Southwest corner of the state


Snuffbox (Epioblasma triquetra) Candidate Small to medium creeksand rivers

Chisago and Washington


Steps to Protect Endangered Species

w Know the endangered, threatened and candidate species that live in your area.

w Before applying pesticides on another person’s land, learn if a protected species lives on the property being treated or on adjoining land. For the most part, landowners know of the presence of protected species from field work conducted by the Minnesota Department of Natural Resources.

w Use strategies to prevent damage to non-target organisms, including application setbacks, reduced rates, and application timing. Delay or forgo pesticide application if protection of endangered or threatened species cannot be ensured.

w Look for EPA Endangered Species Protection Statements when reviewing pesticide labels.

w When an EPA Endangered Species Protection Statement appears on a label, check to see if an EPA Endangered Species Protection Bulletin exists for the county in which the pesticide will be used. Call the telephone number or visit the website provided. The bulletin is part of pesticide labeling—if one exists, you need to obtain, read, and follow it.

w Obtain a new Endangered Species Protection Bulletin if the one you have will be more than six months old on the day you apply the pesticide.

Landowners and applicators can find out if federal or state listed endangered, threatened, or candidate species are in the area. See the DNR website at www.dnr.state.mn.us/rsg/index.html or call the DNR at (651) 296-6157 or (888) 646-6367. For more information, contact:

w U.S. Environmental Protection Agency Endangered Species Protection Program Office of Pesticide Programs www.epa.gov/espp (703) 305-5239

w U.S. Fish and Wildlife Service Twin Cities Ecological Services Field Office www.fws.gov/midwest/twincities (612) 725-3548

w Minnesota Department of Natural Resources Natural Heritage and Non-game Wildlife Research Program

http://www.dnr.state.mn.us/eco/nhnrp/index.html (651) 259-5073

Prairie bush clover, a threatened species, is found in agricultural areas of the state. Photo: DNR

chapter 5 protecting the environment

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