orchidpestsanddiseasesbysuebottom

8/7/2019 OrchidPestsandDiseasesbySueBottom

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Orchid Pests and DiseasesDiagnosis, Treatment and Prevention

by Sue Bottom, [email protected]


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Common Orchid Pests

Plant Sap Feeding Insects Scale

Mealybugs Aphids Thrips Whiteflies

Spider Mites

Chewing Pests Snails and Slugs Caterpillars Roaches and Grasshoppers


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Symptoms and Treatment of Sap Feeding Insects

ScaleSymptoms: Scale are sucking insects that

attach to and feed on the underside of leaves,in leaf axils, on pseudobulbs and on rhizomes.They often are hidden under old leaves andpseudobulb sheaths. Severe infestationscause chlorotic areas to appear on the leavesand plant surfaces which will yellow and maydarken and can cause the leaf to drop

prematurely.

Treatment: If there are only a few scale, use aQ tip dipped in isopropyl alcohol or toothbrushdipped in a pesticide like Malathion, Orthene orSafer Soap (used per label instructions) tophysically remove scale. For more severe

infestations, apply the pesticide at the crawlerstage and repeat the application 2 weeks later.Be sure to spray all plant surfaces, particularlythe undersides of leaves and leaf axils.

Prevention: Remove old leaf and flowersheaths to eliminate scale hiding places and

allow easy inspection. Check new plantscarefully before adding to the growing area.


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Mealybugs

Symptoms: Mealybugs are sucking insectsthat attack any part of the plant but tend tostay tucked away at the junction of leaf andstem. Severe infestations cause chloroticareas to appear on the leaves, which maydarken, causing the leaf to yellow and dropprematurely.

Treatment: If there are only a fewmealybugs, use a Q tip dipped in isopropylalcohol or toothbrush dipped in a pesticidelike Malathion, Orthene or Safer Soap (usedper label instructions) to physically removethe mealybugs. For more severe

infestations, apply the pesticide and repeatthe application 2 weeks later. Be sure tospray all plant surfaces, particularly theundersides of leaves and leaf axils.

Prevention: Remove old leaf and flowersheaths to eliminate hiding places and allow

easy inspection. Check new plants carefullybefore adding to the growing area.


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Aphids

Symptoms: Aphids are sucking insectsthat attack buds, flowers and new growthsand transmit disease from plant to plant.Buds and flower may fail to open andleaves may have a sticky deposit.

Treatment: Wash aphids away from the

plant with a jet of water. Plants can besprayed with a pesticide like Malathion,Orthene or Safer Soap using the productin accordance with label instructions.

Miscellaneous: The honeydew excreted

by aphids and other sucking insects isattractive to ants and is an ideal mediumfor sooty mold. When sooty mold ispresent, inspect the plants for aphids,mealybugs, scale and mites.

pictures courtesy of the American Orchid Society


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Thrips

Symptoms: Thrips are very small suckinginsects that feed on flowers and occasionallyleaves and can transmit disease from plant toplant. Infested buds may not open andflowers may be deformed exhibiting watersoaked spots. Leaves may appear pitted,stippled, silvery or bleached.

Treatment: Plants and flowers can besprayed with a pesticide like Orthene,Malathion or Safer Soap, applied inaccordance with label instructions. Repeatapplications will be required because thripsremain hidden on the plant or can bereintroduced to the plant from other flowers in

the landscape.

Control: Good sanitation will help preventinfestation as will keeping plant hosts(flowers, citrus, gardenias, eucalyptus, etc.)separate from your orchids.


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Whiteflies

Symptoms: Whiteflies are small, moth-likeinsects that attack buds, flowers and new

growth. The tell tale sign of whiteflies is a

cloud of tiny white insects arising from an

affected plant when it is moved or disturbed.

Treatment: Plants can be sprayed withMalathion, Orthene or Safer Soap following

label instructions. Repeat applications at 4

day intervals until whiteflies are no longer

present.

Control: Good sanitation and elimination ofweeds will help prevent infestation as will

keeping plant hosts separate from your

orchids.

bottom picture courtesy of the American Orchid Society


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Symptoms and TreatmentSpider Mites

Symptoms: Mites are not insects, they are members of the

arachnid family. Mites typically feed on the underside of theleaves and can be found under the leaves as small, red tobrown pests. A hand lens may be needed to see them. Leafundersides may have webbing and brown splotches from themite excrement. The upper surface of a damaged leaf mayhave a silvery sheen that eventually becomes sunken andturns brown. Leaves may be streaked, stippled or spotteddue to lack of chlorophyll.

Treatment: Plants can be sprayed with a miticide likeKelthane following label instructions being particularly carefulto contact all the undersides of the leaves. During warmweather, new generations mature every 6 days so repeatapplications will be required, perhaps 3 applications at 4 dayintervals.

Prevention: Mites appear during warm, dry weather.Increasing humidity and leaf wetness and, if possible,decreasing temperature help prevent infestations.

Two bottom pictures courtesy of the American Orchid Society


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Symptoms and Treatment of Chewing Pests

Snails and Slugs

Symptoms: These mollusks will leaveholes and notches in the leaves, flowersroots and may chew off the growing tips.Chewed areas may also appear on buds.These nocturnal pests travel on a layer ofslime and this slime trail is evidence of theirpresence.

Treatment: Chemical baits may be placedin the growing area. Ash and diatomaceousearth can be spread on horizontal surfacesto create a barrier though water willdeactivate it. Beer in shallow tins can bespread in the growing area and the drownedpests removed the next day. Regularapplications will have to be used becausewatering will disperse the controls.

bottom pictures courtesy of the American Orchid Society


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CaterpillarsSymptoms: Caterpillars are the immature

stage of moths and butterflies. While notcommon, they are voracious feeders that cando a great deal of damage to flowers andleaves in a short period of time.

Treatment: Caterpillars can be physicallypicked off the plant and destroyed, check theunderside of leaves for their presence.Bacillus thuringiensis or Bt is a naturallyoccurring bacteria of insects, it is a safe andnatural product that can be sprayed in thegrowing area following label instructions.

Prevention: Keep the growing area clean ofof fallen leaves and debris in which insectpests and their eggs can hide. Keep thelandscape free of caterpillars.



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Cockroaches and Grasshoppers

Symptoms: Cockroaches andgrasshoppers cause damage by eatingflowers, roots and new growths.

Cockroach Deterrence: Cockroach baitscan be spread in the growing area or apaste of boric acid, sugar and flour mixed

with water can be spread in every nookand crevice you can find. Dont get any of

the stuff on the plants themselves.Another approach is to water and thenflush a mix of liquid Sevin (1 tsp/gal)through the pot.

Grasshopper Deterrence: Crush thegrasshoppers with a brick, shoe, etc.Partially bury jars filled with molasses andwater and remove drowned victims thenext day.

pictures courtesy of the American Orchid Society


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Pesticides for the Treatment of Orchids


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Common Orchid Diseases

Bacterial and Fungal Rots

Leaf Spots and Foliar Blights

Flower Spots and BlightsThe symptom descriptions and prevention tips are extracted

from Orchid Species Culture, Margaret L. and Charles O. Baker


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Bacterial and Fungal Rots

Bacterial Diseases Soft and Brown Rots Erwinia

Bacterial Brown Spot Acidovorax(syn.Pseudomonas)

Black Rot Pythiumand Phytophthora

Fungal Diseases Fusarium Wilt Fusarium

Root Rot Rhizoctonia


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Symptoms of Bacterial Soft and Brown RotErwinia spp.

Symptoms: Small water-soaked spotsappear on the leaves and often aresurrounded by yellow halos. Ifunchecked, the infection will rapidly rotthe leaves and roots and spread moreslowly into the rhizomes or pseudobulbs.

This wet rot may have a foul odor andhas a water soaked appearance.

In Phalaenopsis, the disease spreads sorapidly that plants may be completelyrotted in 2-3 days. The bacteria are

opportunistic organisms that can enterthrough wounds.

Dendrobiumleaves appear yellow andwater-soaked and become black andsunken.


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Symptoms of Bacterial Soft and Brown RotErwinia spp.

Symptoms (contd): Vandaleavesdevelop translucent patches whichbecome black and sunken.

Paphiopedilumleaves develop small,round spots that are initially yellow and

water-soaked but eventually becomereddish brown and sunken. The spotenlarges in all directions and mayreach the growing crown before theleaf tip is affected. If untreated, thedisease quickly spreads throughout the

plant, leaving it a dark, shriveled mass.

Grammatophyllumleaves have water-soaked, browning spots which becomeblack and sunken.


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Symptoms of Bacterial Brown SpotAcidovorax(syn. Pseudomonas)

Symptoms: The symptoms may appearanywhere on the leaf as a small, soft, water soakedblister. Initially dirty green in color, the infected spotenlarges, coalesces and eventually becomesbrown or black, dried up and sunken. It oozesbacteria-laden liquid, particularly when the disease

reaches the tip of the leaf. It is most prevalentduring the warmer weather.

In Cattleya, the infection enters through wounds onolder plants and usually affects only older leaves.It advances slowly and is rarely fatal.

In Phalaenopsis, the blister-like spots may besurrounded with a yellowish or pale green halo.Spots coalesce, and the infection spreads rapidly.If the diseased area invades the crown, the plantwill die.


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Treatment of Bacterial Brown SpotAcidovorax(syn. Pseudomonas)

Treatment: Immediately removeinfected tissue and spray the plant witha bactericide like Physan or coppercompounds following label instructions.Disinfect growing area with 10% bleachsolution.

Prevention: Pseudomonas cattleyais awater-borne pathogen that preferswarm, moist conditions. Reducehumidity and temperature (if possible),eliminate overhead watering and

increase air circulation.


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More Pictures of Bacterial Brown SpotAcidovorax(syn. Pseudomonas)


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Symptoms of Black RotPythium & Phytophthora spp.

Symptoms: The infections usually startson the leaves, new leads or roots, thoughall plant parts are susceptible. Thedisease spreads rapidly and will kill theplant unless treated promptly.

Leaf symptoms first appear on theunderside as small, irregular, watery,brown spots which rapidly becomepurplish brown or purplish black. Thespots may have a yellowish advancingmargin. The lesions enlarge with age and

may ooze water if pressed. Old lesionssometimes become dry and black, oftenallowing other diseases to attack the plant.The disease may spread rapidly to therhizome and roots, particularly when thetemperature and humidity are high.

top picture courtesy of the American Orchid Society


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Symptoms of Black RotPythium & Phytophthora spp.

Symptoms (contd): New leads show apurple or purple-brown area with a yellowishadvancing margin and may be pulled offeasily.

Pseudobulbs, roots or rhizomes show

infections as purplish-black, often sharplydelineated, discolored area in the center ofthe plant. The infection often starts in theroots and may spread upward to the base ofthe pseudobulb or leaf, causing the plant towilt.

Cattleyasmay show a creamy yellowdiscoloration on one or both sides of thepseudobulbs. The discoloration eventuallyturns black or brown and softens, and the bulbrots.

Picture courtesy of Robert A. Cating


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Treatment of Black RotPythium & Phytophthora spp.

Treatment: Unless the plant is valuable,the best approach is to discard it, as thedisease is highly contagious and willspread from plant to plant from splashingwater. If the plant is valuable, isolate itfrom your other plants, remove infected

tissue with a sterile tool, and drench witha suitable fungicide like Subdue orBanrot following label instructions.

Prevention: High temperatures andhumidity contribute to the spread of the

disease. Consider using a preventativefungicide spray, particularly during hothumid periods, following labelinstructions.


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Symptoms of Fusarium WiltFusarium sp.

Symptoms: Fusarium blocks the flow of

moisture through the plants vascularsystem plugging the phloem. Infectedleaves are yellow, thin, shriveled, wrinkledor wilted and eventually die.

The diagnostic symptom in the plant is a

circle or band of purple or pinkish-purplediscoloration on the outer layers of therhizome evident when the rhizome is cut.If the disease is extensive, the entirerhizome may turn purple, and thediscoloration may extend to the

pseudobulbs. The pathogen is spreadthrough improper hygiene, generally as aresult of using nonsterile cutting tools,which transfers the fungus from plant toplant. Severely infected plants may die in3-9 weeks, while mildly infected plants

gradually decline over a year or so.


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Symptoms and Treatment of Fusarium WiltFusarium sp.

Treatment: Discard infected part ofrhizome and pseudobulb if the purpleband is evident. Repot only the part ofplant showing no purple discoloration.Drench sanitized plants in a thiophanatemethyl (like Cleary's 3336) following

label instructions. Be diligent indisinfecting growing area and cuttingtools. Each time the cutting toolcontacts infected tissue, it should besterilized before making a second cut.

Prevention: Prevention is a simplematter of following proper hygiene.Sterilize cutting tools after each use,preferably through flame sterilization.


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Symptoms of Fungal Root RotRhizoctonia sp.

Symptoms: Root rot occurs when the

medium breaks down, drainage is poor and/orplants are overwatered. Rot sets in quicklywhen roots are damaged by injury or saltbuildup from hard water or over fertilizing.Rhizoctoniais very contagious and if thedisease is not controlled immediately, infected

plants develop brown root rot and die.

Rhizoctoniais primarily a root disease, but thesymptoms can be noticed on aerial parts ofthe plant. Leaves and pseudobulbs becomeyellow, shriveled, thin and twisted and newgrowths become progressively smaller. Theroots usually show a brown rot with white orbrown fungal growth. In severe infections, thefungus girdles and kills the plant. Theinfection quickly invades the lower leaves and

rhizomes of small seedlings.


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Treatment of Fungal Root RotRhizoctonia sp.

Treatment: Remove infected part of rootsand leaves using a sterile cutting tool,drench the remaining plant in a protectantfungicide like thiophanate methyl (such asCleary's 3336) or systemic fungicide (suchas Subdue) following label instructions.Disinfect growing area with 10% bleachsolution.

Prevention: Make sure your potting mediais fresh and your plants are not overwatered.When disease is suspected in other plants

or when repotting is overdue, unpot theplants, check their roots and repot asnecessary. In hard-water areas, pots shouldbe flushed at least monthly to prevent rootdamage by watering heavily to solubilize thesalts and then watering heavily an hour later

to flush the salts from the pot.


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Leaf Spots

Foliar and Petal Blights

Fungal Diseases

Anthracnose Colletotrichum(syn.Gloeosporioides)

Cercospora Leaf Spot - Cercospora

Guignardia/Phyllosticta Leaf Spot Guignardia & Phyllosticta

Septoria Leaf Spot Septoria

Botrytis Petal Plight - Botrytis


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Symptoms of AnthracnoseColletotrichum& Glomerella spp.

Symptoms: This fungal disease infectsthe aerial portion of the plant. The leavesare most often attacked. Leaf tips turnbrown beginning at the apex andproceeding toward the base. Dark brownor light gray patches develop, sometimesas concentric rings or as numerous darkbands across the leaf. The affected areais usually sharply defined and somewhatsunken, while the remainder of the leafappears normal. Sporing bodies developin the infected area.

Flowers develop watery, black or brownpustules which are usually raised andoccur on the underside of older sepalsand petals. The spots may merge andcover the entire flower.


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Treatment of AnthracnoseColletotrichum& Glomerella spp.

Treatment: Systemic fungicidelike thiophanate methyl (likeCleary's 3336) or protectantfungicides like Mancozeb,following label instructions.Alternate systemic and

protectant fungicide use.

Prevention: Normal sanitation,good air movement, lowertemperatures (if possible) andincreased light may help reduce

the spread of this disease. Thepathogen is most active inwarm weather when light is lowand moisture is high.


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Symptoms of Cercospora Leaf SpotCercospora spp.

Symptoms: Infection shows first as ayellow spot on the underside of the leaf.Soon after infection occurs, the yellow-green area may be noted on the top surfaceof the leaf. The spots continue to enlarge ina circular or irregular pattern and mayeventually cover the entire leaf. With age,the spots become slightly sunken andnecrotic and change to purple-brown orpurple-black. The advancing marginremains yellow. Heavily infected leavesusually fall from the plant prematurely,

especially in the infection started near thebase of the leaf. As the spots enlarge inirregular patterns, they become sunken andturn purplish brown to purplish black. Thetop surface of the leaf first becomeschlorotic and finally necrotic.



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Symptoms of Guignardia Leaf SpotGuignardiaand Phyllosticta spp.

Symptoms: The first signs ofGuignardiainfection are tiny, darkpurple, elongate lesions on eitherleaf surface. These lesions runparallel to the veins and elongateinto purple streaks or diamond-shaped areas. Spots often merge toform large irregular lesions that mayaffect a large part of the leaf. Withage, the center of the lesion turnstan. Raised, black sporing bodiesdevelop in the affected area. Affects

mostly Ascocentrumand Vandasandtheir hybrids and may indicateinsufficient light. This blight is alsoknown as Phyllosticta; the namesapply to two different sexual stagesof the same fungus.


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Symptoms of Phyllosticta Leaf SpotGuignardiaand Phyllosticta spp.

Symptoms: Spotting from Phyllostictamay start anywhere on the leaf orpseudobulb. The lesions are tiny, yellowand slightly sunken. As they enlarge, theybecome round to oval and more sunken,especially if the infection is on the leaves.

With age, they turn tan to dark brown anddevelop a slightly raised, red to purple-black margin. Eventually, tiny black,raised spore structures develop in thecenter of the spots. Individual spots areabout in across. Severely infected

leaves may drop prematurely. Its presencemay indicate insufficient light. This blightis also known as Guignardia; the namesapply to two different sexual stages of thesame fungus.

Bottom picture courtesy of the American Orchid Society


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Symptoms and Treatment of Leaf SpotsCercospora, Guignardia, Phyllosticta & Septoria

Symptoms of Septoria: The tiny spots may starton either leaf surface as sunken, yellow lesions.They continue to enlarge, becoming dark brown toblack, circular or irregular lesions. Spots maymerge to form large, irregular patches on the leaf.Heavily infected leaves fall prematurely.

Treatment: Remove infected leaves with a sterileinstrument and reduce leaf wetness. Spray with asystemic fungicide such as thiophanate methyl(Cleary's 3336) or a protectant fungicide likeMancozeb, following label instructions. Alternate

systemic and protectant fungicides.

Prevention: Good sanitation with good airmovement. Reduce leaf wetness, water on theleaves may lead to infection. If the fungus is acontinuing problem, monthly fungicide sprays may

offer effective prevention.


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Symptoms and Treatment of Botrytis Petal BlightBotrytis sp.

Symptoms: Very small, black or light brown,spots on the flowers. The spots may enlargeand cover the entire flower. If conditions aremoist, a gray fungal growth may appear onseverely infected or decaying flowers.

Treatment: Remove infected flowers, thenspray with a protectant fungicide like Daconil.In enclosed areas, a smoke bomb ExothermTermil (Daconil). Always follow labelinstructions. This fungus is common in theenvironment and cannot be eradicated.

Prevention: Remove infected flowers sincethese are reservoirs of infection. Infectionmay be reduced through careful sanitation,increased air circulation, reduced humidityand warmer night temperatures (>68oF).

Fungicides and Bactericides for the


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Fungicides and Bactericides for theTreatment of Orchid Diseases


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Viruses

Symptoms Chlorotic andnecrotic spots, streaks, lines andrings in the leaves. Flowers

may show necrotic spots andstreaks as well as color break.The virus, if present, is presentin all parts of the plant.

Treatment There is notreatment for a virused plant.

Destroy the plant to prevent itfrom infecting other plants. Ifthe plant is valuable, isolate itcompletely from other plants andfollow precautions to preventinfecting other plants.

First picture courtesy of the American Orchid Society


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VirusesUse Sterile Cutting Tools

Viruses are spread by transmittingthe plant sap from one plant toanother via mechanical means.The primary means by whichviruses are spread from plant to

plant is by improperly sterilizedcutting tools. There are two waysto keep cutting tools sterilized,either use sterile single edgedrazor blades that are discarded

after each and every use or use ahot flame to sterilize cutting toolsafter using the tools on a givenplant. The cutting tool should besterilized for 15 to 20 secondswith a hot flame on each side.

Cymbidium Mosaic Virus


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Viruses

Control During Repotting

Viruses can be spread whenever there ismechanical transmission of sap from aninfected plant to another plant, even byleaves rubbing against one another.Observe these additional controls: Latex Gloves. Wear latex gloves

when handling a given plant anddiscard those gloves when you aredone handling the plant. Your barehands can come into contact with plantsap containing the virus and infect thenext plant.

Newspaper on Potting Surface.

Keep the potting surface sterile. Keepa stack of newspapers handy andwhen repotting, place newspaperunder the potting area. Uponcompletion, wrap up the newspaper,gloves and other detritus and discardthem before touching the next plant.

Tobacco Mosaic Virus


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Viruses

Disinfect your Pots Prior to Use

Make sure your pots are sterile. Disinfection of Plastic Pots

Plastic pots can be disinfected by

first washing them with soap to

remove residual organic matter,

then soaking them for an hour in a

20% bleach solution, then soaking

them for an hour in Physan mixed

per label instructions.

Disinfection of Clay Pots Clay

pots are porous and cannot be

sterilized against viruses by usingbleach and Physan alone. Follow

the normal disinfection routine for

plastic pots above and then bake

them in the oven at 350oF for an

hour to kill any residual virus.

Tobacco Spotted Wilt Virussyn. Odontoglossum Ringspot Virus


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VirusesControl During Routine Activities

Viruses can be spread whenever there ismechanical transmission of sap from aninfected plant to another plant, even byleaves rubbing against one another. Observethese additional controls: Cutting Inflorescences. Use a sterile

tool to cut each inflorescence from the

plant. The easiest way to do this is touse a sterile, single edged razor blade toremove the inflorescence and discard itafter each use (or bake in a 350F ovenfor an hour). If you use shears, youshould flame sterilize them between eachinflorescence.

Removing Inflorescences by Hand.Dont do it! A virus, if present, can beunknowingly transmitted to your handand you can infect the next plant whenyou touch it or remove the next deadflower bud by hand. Instead, use asterile razor blade and discard it after

each use.

Tospovirus

Orchid Fleck Virus


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Other Types of Damage

Edema

Cold Sunburn

Fertilizer Burn

Salt Toxicity


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Other Types of Damage - Edema Excess water is absorbed by

the roots quicker than it is lostby the leaves, causing swellingof plant cells and producing ablister-like lesion.

Occurs when plants watered

during warm days and thenights turn cool or duringperiods of cool weather whenwater quantity and/orfrequency is not reduced.

The blister-like symptoms canappear on upper or lower leafsurfaces, stems, petals or

sepals.Pictures courtesy of Robert A. Cating


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Other Types of Damage - Cold Symptoms of Chilling

Surface lesions, pitting, large, sunkenareas and discoloration. Water-soaking intissues, usually followed by wilting andbrowning.

Internal discoloration (browning). Accelerated rate of natural death. Increased susceptibility to attack by fungi

and bacteria.

Slowed growth, or limited growth flush.This may be difficult to detect without non-chilled plants for comparison or a thoroughknowledge of the orchids normal growth

rate.

Symptoms of Freezing Desiccation or burning of foliage.

Water-soaked areas that progress tonecrotic spots on leaves and death ofsections of the plant or the entire plant.

Obvious symptoms may not be presentuntil after the plant has been stressed bywarm temperatures.


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Other Types of Damage - Sunburn

Sudden appearance of black spots

on leaves when the leavesbecome overheated from too muchlight, a sudden increase in lightduring the change in season ormoving plants outdoors in thespring. Burn fades to thin tannish

leaf scar over time.

top middle photo courtesy of the American Orchid Society


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Other Types of Damage Fertilizer Burn

Fertilizer Burn on Flowers If you getwater soluble fertilizer on your flowerswhile you are watering, you have thepotential for burning the flowers,particularly if you use a full strengthrather than dilute fertilizer. The fertilizersalts will burn the flower leaving a water

soaked spot. Fertilizing blooming plantsmay also shorten the blooming time.

Prevention - After youre donefertilizing, come back with a plain waterspray on the flowers to wash the

fertilizer off the flowers to prevent theirspoiling. It is safer to use a more dilutefertilizer, say to of the labeled

strength, unless you determine yourplant needs a higher fertilizerconcentration.


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Other Types of Damage Salt Toxicity

Salt buildup. Salts present in your water supply and added by fertilizersaccumulate over time. Salt buildup looks like whitish to brownish crusts on themedium and around the pot, or on the surface of the mounting substrate onmounted orchids, and can be a sign of over-fertilizing. If allowed to remain,those salts will negatively impact the health of your plant. Excess fertilizer saltsburn and kill orchids..

Symptoms. Lack of root growth may indicate an unhealthy concentration ofmineral salts in the medium, on up to full fertilizer burn. If this is suspected,decant the plant and check its roots. Dead root tips, brown roots or salt crust onthe potting medium surface are signs of trouble. In later stages, brown leaf tips,leaves and eventually pseudobulbs may appear, indicating burned roots. Ifallowed to continue, fertilizer burn will eventually kill the plant.

Prevention. It is preferable to use a dilute fertilizer, say to of the labeledstrength. Flush the pot monthly by watering with copious amounts of water tosolubilize salts and then watering again an hour later to flush accumulated saltsfrom the pot.

Pictures and text courtesy of the American Orchid Society

orchidpestsanddiseasesbysuebottom

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