ANR-1214

A L A B A M A A & M A N D A U B U R N U N I V E R S I T I E S

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Leaf Spot Diseases

There are two common fungal

leaf spot diseases that may

damage pansies, Viola x wittrock-

iana, in the landscape or green-

house. Anthracnose, caused by

Colletotrichum gloeosporioides,

and Cercospora leaf spot, caused

by Cercospora violae, each causes

severe damage to the overall

appearance of pansy plantings

and reduces the economic value

of greenhouse crops. Both dis-

eases require high relative

humidity and moisture for their

development and spread.Anthracnose can be a

problem in landscape and green-house plantings throughout thegrowing and production seasons,respectively. Symptoms firstappear as pale white or cream-colored circular spots (one-eighthto one-fourth inch in diameter) onupper surfaces of leaves andoccasionally on stems (Figure 1).Spots have thin dark brown orblack borders. Often spotting ismost severe on lower leaves

Diseases of Pansiesand Their Control

where humidity is highest. Whenconditions are humid or wet, tinyblack specks may appear on thesurface of spots. These specksdevelop into spore masses of thefungus. Splashing rain or irriga-tion droplets falling onto spore

Figure 1. Anthracnose leaf spots onpansy

Figure 2. Cercospora leaf spot onpansy

Figure 3. Small white spots of pow-dery mildew in early stages of develop-ment on pansy leaves

Figure 5. Botrytis at 10X magnification

Figure 6. Myrothecium crown rotwith black fruiting bodies and whitespore masses at 10X magnification

Figure 4. Botrytis flower stemblight with fungal growth

Figure 7. Black roots typical ofThielaviopsis black root rot (Healthyplant on the right and diseased planton the left)

masses disperse the spores tonearby healthy foliage. New spotstypically appear on the previouslyhealthy leaves and stems about 1week after infection.

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Cercospora leaf spot occursmost frequently in landscapeplantings in early to midspring.Outbreaks of this disease alsodevelop in early fall on green-house flat- and pot-grown pan-sies. Spots are approximately one-fourth inch in diameter, circular,and dark charcoal gray with aslightly raised feathery texture(Figure 2). Lower leaves are oftenseverely spotted and usually fallfrom the plants. Spores of thefungus, which are produced whenconditions are humid, are easilymoved to nearby healthy foliageby wind currents and splashingwater droplets. New leaf spotsappear about 1 week after sporedispersal and infection begin.

Control of these leaf spot diseases involves (1) removal ofseverely spotted plants or leaves;(2) modification of watering prac-tices so that foliage does notremain wet for prolongedperiods; and (3) fungicide appli-cations, which are needed insome situations. In landscapes orgreenhouses, removal of infectedplants is recommended. If diseasedplants are not removed, they willserve as a reservoir of inoculumfor future disease spread. If pos-sible, fallen leaves should beremoved from the area. In thelate fall, the areas where diseaseis present should be thoroughlycleaned by removal of all pansy

debris. When preparing to plantin the spring, bedding plant loca-tions should be rotated so that the same type of plants are notinstalled into the same areasevery year. Greenhouses shouldbe thoroughly cleaned betweencrops. All pansy debris should be removed from the house.Benches, pots, tools, and floorsshould be thoroughly cleaned of debris. In landscapes, irrigationshould be scheduled for themorning so that the foliage willdry quickly. Bedding plantsshould be located in landscapeareas with well-drained soil.Greenhouses should follow similarpractices regarding irrigation anddrainage. Where large numbers ofplants are involved, application of protective fungicide sprays isoften recommended. Label direc-tions should be followed carefully.See Table 1 for specific fungicideslabeled for the control of thesediseases.

Powdery MildewPowdery mildew may occur

in March and April in landscapeplantings of pansy. Fluctuatingtemperatures typical of spring andfall and high humidity are condi-tions favorable for disease devel-opment and spread. Althoughpowdery mildew will not directlykill pansy, severe infections may

reduce their vigor and ultimatelyspeed up plant decline. Pansy cul-tivars differ considerably in theirsusceptibility to powdery mildew.

Small discrete, faint whitepatches that consist of numerousthreadlike hyphae and spores ofthe causal fungus Sphaerothecamacularis appear on the petiolesand leaves (Figure 3). Thesepatches increase in size until theentire leaf surface is covered bythe white threadlike growth of thecausal fungus.

Typically, outbreaks of pow-dery mildew on pansy becomenoticeable shortly before theplants are replaced with summerannuals. As a result, protectivefungicide treatments are rarelyneeded to protect plantings ofpansy from powdery mildew.Plantings should be periodicallyinspected for disease symptoms.If the characteristic white coloniesare seen and the plants areyoung, then begin fungicideapplications. See Table 2 for a listof fungicides cleared for the con-trol of powdery mildew on pansy.The fungicides used to controlCercospora leaf spot (Table 1)will also control powdery mildew.

The severity of powderymildew varies considerablyamong cultivars of pansy. In fieldtrials in Alabama, ‘Bingo ClearAzure,’ ‘Imperial Silver Blue,’

Table 1. Anthracnose and Leaf Spot Diseases

Fungicides Rates Commentsper gallon per 100 gallons

azoxystrobinHeritage 50W —- 1 to 4 oz. Apply to foliage to runoff before symptoms are seen. Reapply

chlorothalonil as needed every 7 to 14 days. Shorten interval and increase Daconil Weather Stik —- 13⁄8 pt. rate when conditions favor disease development. Add a small Daconil Ultrex —- 1.4 lb. amount of a spreader sticker or liquid detergent (1⁄4 tsp. per Daconil 2787 4F 2 t. 2 pt. gallon) to improve coverage of foliage with wettable powder

mancozeb (W) formulations.Fore 80W 1 T. 1.5 lb.

thiophanate-methyl3336 50W —- 12 to 16 oz.3336 4.5F —- 10 to 20 fl. oz.Halt 50W 1 T. —-

trifloxystrobinCompass 50W —- 2 to 4 oz.

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Diseases of Pansies and Their Control 3

‘Crown Orange,’ and ‘ImperialBeaconfield’ developed extensivepowdery mildew of the foliage.Little if any damage was seen on most of the remaining pansycultivars evaluated.

Botrytis BlightBotrytis blight, caused by the

fungus Botrytis cinerea, may bea problem in the landscape andin greenhouse production.Temperatures in the low 50s to upper 70s combined with prolonged periods of highhumidity and frequent rain oroverhead irrigation favor diseasedevelopment. Flowers andflower stems are especially sus-ceptible to attack by Botrytis.

Botrytis blight causes brownspots or blotches on flowers andflower stems (Figure 4). When thedisease is severe and conditionsare wet, leaves and major stemsmay become spotted, cankered,and blighted. In some situations,individual spots on leaves mayhave a slight zonate pattern.Severely damaged plants may col-lapse and die. When humidity ishigh, the fungus will form a darkto light gray webby growth onthe surfaces of blighted leavesand flowers. If examined closely,the fungal growth may display abranchlike network with scat-tered, small light gray knots orclusters (Figure 5). Such knots or clusters are groups of sporesthat will be dispersed to nearby

foliage by wind currents orsplashing water.

Disease control involves (1)removing diseased plants; (2)reducing humidity and moisture;and (3) in certain cases, applyingprotective fungicide treatments. Ina greenhouse, diseased plantsshould be removed. Productionbenches, pots, and tools shouldbe thoroughly cleaned. For detailson this clean-up process, seeExtension publication ANR-753,“Identification and Control ofBotrytis Blight on Floral Cropsand Woody Ornamentals.” Irriga-tion should be applied at middayso that foliage does not remainwet during night hours. Plantsshould be spaced and fans shouldbe adjusted so that relativehumidity is kept as low as pos-sible. Heating cool air to tempera-tures of 75 degrees F or higherand venting warm moist air willhelp prevent continued develop-ment of the fungus, especiallywhen these practices are appliedduring evening hours. Protectivefungicides are recommended inmany greenhouse situations whenBotrytis blight has been detected.See Table 3 for fungicides labeledfor Botrytis control on pansy, andfollow all label directions.

Botrytis blight on pansy in thelandscape is a problem onlywhen the weather is cloudy, mild,or slightly cool with highhumidity and abundant moisture.Botrytis does not readily spread

under conditions of low humidity.When disease does occur, how-ever, it is wise to remove the dis-eased plants and, if possible,increase plant spacing to improveair circulation. Planting pansies inlow wet areas should be avoided.Watering should be done middayso that foliage will dry quickly.Applications of a protective fungi-cide are recommended onlywhere large plantings areinvolved. See Table 3 for fungi-cides labeled for Botrytis control,and always follow label recom-mendations.

Myrothecium Crown RotThe fungus Myrothecium ror-

idum causes a crown (lowerstem) rot and a petiole rot ofpansy. This disease is typically aproblem in greenhouses; how-ever, Myrothecium crown rot hasbeen observed occasionally inlandscape plantings. Infection anddamage occur under conditionsof moderate temperatures andmoderate soil moisture.

Symptoms begin as a brownsoft rot of the crown and possiblythe nearby leaf petioles (Figure6). When crown rot is severe, arapid wilt and collapse of theplant follow. Tiny white andblack bodies (spore masses), justbarely visible as specks, usuallydevelop on the infected crowns(Figure 6). The white sporemasses are easily spread bysplashing or flowing water. When

Table 2. Powdery Mildew

Fungicides Rates Commentsper gallon per 100 gallons

azoxystrobinHeritage 50W —- Apply to foliage at first sign of disease. Reapply every 7 to 14

thiophanate-methyl days as needed. Shorten interval and increase rate when 3336 50W —- 12-16 oz. conditions favor disease. Add a small amount of a spreader3336 4.5F —- 10-20 fl. oz. sticker or liquid detergent (1⁄4 tsp. per gallon) to improve Halt 50W 1 T. —- coverage of foliage with wettable powder (W) formulations.

parafinnic oilSun Spray UltraFine Oil 1% v/v 1 gal.

trifloxystrobinCompass 50W —- 2-4 oz.

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Table 3. Botrytis Blight

Fungicides Rates Commentsper gallon per 100 gallons

azoxystrobinHeritage 50W —- 4 to 8 oz. Apply to foliage and flower buds when disease is observed.

chlorothalonil Reapply as needed every 7 to 14 days. Shorten interval andDaconil Weather Stik —- 13⁄8 pt. increase rate when conditions favor disease. Add a smallDaconil Ultrex —- 1.4 lb. amount of a spreader sticker or liquid detergent (1⁄4 tsp. perDaconil 2787 4F 2 t. 2 pt. gallon) to improve coverage with wettable powder (W)

fenhexamid formulations.Decree 50W —- 1.0 to 1.5 lb.

iprodioneChipco 26019 50W —- 1 to 2 lb.

mancozebFore 80W 1 T. 1.5 lb.

thiophanate-methyl3336 50W —- 12 to 16 oz.3336 4.5F —- 10 to 20 fl. oz.Halt 50W 1 T. —-

trifloxystrobinCompass 50W —- 2 to 4 oz.

infected plants are pulled, theshoots frequently separate fromthe roots. Wounding frommechanical transplant machineshas been shown to possiblyincrease disease susceptibility andincidence.

Disease control in a green-house situation requires disposalof all diseased plant material,associated cell packs or pots, andmedia. Trays, benches, and toolsshould be thoroughly cleaned anddisinfected before reuse. In manygreenhouse situations, it may bemore practical, effective, and eco-nomical to replace plug flats andflats rather than cleaning theseitems. Irrigation should be appliedso as to insure that plants do notremain wet for prolonged periods.Protective fungicide treatments are

often recommended when the dis-ease has been observed in thehouse or area. See Table 4.

In the landscape, disease control requires removal of thedamaged plants and all plantdebris. Also, pansies should notbe grown in the diseased area forthe next 1 to 2 years. Wateringpractices should be adjusted sothat plants do not remain wet forprolonged periods. Low wet areasfor plantings should be avoided.Fungicides are not generally rec-ommended in landscape areasunless the plantings are extensive.

Black Root RotBlack root rot is a disease

caused by the soilborne fungusThielaviopsis basicola. The diseasehas been observed in both land-

scape and greenhouse situations,but greenhouse problems areusually more common. Diseasedevelopment is usually favoredby alkaline soil or media (pH 6.5to 8.0), cool to moderate soil tem-peratures (56 to 77 degrees F),and moderate to high levels ofsoil moisture.

Symptoms initially appear asblack spots or bands on the nor-mally white roots. Root tips areoften infected and black in colorwhen spores of the fungus arepresent. In some situations,infected roots become brown andcannot be distinguished from otherroot rot diseases by visual inspec-tion. (Most root rot diseasesrequire laboratory study for anexact diagnosis. See Extensionpublication ANR-450, “Plant Diag-nostic Lab Services,” for details on

Table 4. Myrothecium Leaf Blight and Collar Rot

Fungicides Rates Commentsper gallon per 100 gallons

Chlorothalonil Apply to leaves, leaf petioles, and root collar, as well as to soilDaconil Weather Stik —- 13⁄8 pt. around base of plant when symptoms are seen. Reapply asDaconil Ultrex —- 1.4 lb. needed every 7 to 14 days. Shorten interval and increase Daconil 2787 4F 2 t. 2 pt. rate when conditions favor disease. Add a small amount of a

spreader sticker or liquid detergent (1⁄4 tsp. per gallon) to improve coverage of foliage with wettable powder (W) formulations.

TrifloxystrobinCompass 50W —- 2 to 4 oz.

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Diseases of Pansies and Their Control 5

submitting plant samples for labo-ratory testing.) As the diseasespreads throughout the rootsystem, the plant becomes increas-ingly unthrifty, stunted, and some-times yellowed, similar to anitrogen deficiency. Wilt may ormay not occur, depending on theplant and the extent of rootdamage. In many cases, stuntingand yellowing of the foliage,beginning with the older foliage,are the only aboveground symp-toms. The entire root system onseverely infected plants maybecome black and rotted (Figure 7).Typically, these plants quicklywither and die. Black root rot usu-ally is spread by movement ofcontaminated water, soil, or plants.

In greenhouses, control ofblack root rot involves removal of infected plants and associatedmedia and pots. Benches, trays,and tools should be thoroughlywashed and treated with a disin-fectant labeled for greenhouseuse. In many greenhouse situa-tions, purchase of new plug flatsand flats would be easier, moreeffective, and more economicalthan attempts to disinfect theseitems. This fungus may be intro-duced into greenhouses in peat-based potting media. Avoid situa-tions of moisture or fertilizationimbalances. Protectant fungicidedrench treatments are frequentlyrecommended to prevent diseasedevelopment. See Table 5 forfungicides labeled for control ofblack root rot on pansy. Alwaysfollow label directions.

Table 5. Thielaviopsis Black Root Rot

Fungicides Rates Commentsper gallon per 100 gallons

Thiophanate-methyl3336 50W —- 12 to 16 oz. Apply as a drench to the media or soil around base of plant 3336 4.5F —- 16 to 20 fl. oz. before symptoms are seen. Reapply, as needed every 1 to 2

months. Shorten interval and increase rate when conditionsThiophanate-methyl + favor disease.

etridiazoleBanrot 40W —- 4-8 oz.

TriflumizoleTerraguard 50W —- 2-4 oz.

In the landscape, pansies withblack root rot should be identifiedand removed quickly. Removesoil associated with roots alongwith the infected plants and plantdebris. Soil pH levels should bechecked and adjusted at orslightly below 6. Avoid plantingpansies in the same area for a 1-to 2-year period. Planting pansiesin areas of good soil drainage andproviding them with appropriatefertilization will help keep themvigorous and less susceptible toblack root rot.

Pythium Crown andRoot Rot

Several species of the soil-borne fungus Pythium arecommon crown and root rot dis-ease agents of pansy and othergreenhouse crops. Wet soil condi-tions for prolonged periods arerequired for this disease todevelop. Plants previouslystressed by drought or applica-tions of excessive levels of fertil-izer are more susceptible to infec-tions by Pythium.

Pythium symptoms initiallyappear as water-soaked, some-times sunken, lesions at the baseof the stem near the soil line oron roots, especially young roots.Infected roots will be light brownin color, slightly darker than thenormal root coloration (Figure 8).In some situations, the color ofdecayed stem or root tissues ishardly discernable from normaltissue color. Decay can be

detected when there is lack ofintegrity or firmness of the tissues.An easy way to check for decayof small roots is to grasp the rootbetween the thumb and fore-finger and pull down gently. If theroot is decayed, the outer cortexof the root will easily slip awayfrom the central root cylinder.Aged root decay becomes darkerbrown in color, similar to otherroot rot diseases. As root deterio-ration progresses, foliage willbegin to wilt and yellow, andplants will become stunted.Dieback can also develop. Water movement can disperse the fungus between infected and healthy plants.

Control of Pythium crownand root rot in greenhousesrequires removal of infectedplants and associated pottingmaterial and pots. Benches, trays,and tools should be washed andtreated with a greenhouse disin-fectant. For many greenhouseoperations, it would be best toreplace plug flats and flats ratherthan attempting to clean and dis-infect these items. Watering prac-tices and potting media should beadjusted to prevent prolongedperiods of water-saturated media.Once Pythium is detected, protec-tive fungicide drench treatmentsare often recommended. SeeTable 6 for fungicides labeled forcontrol of Pythium on pansies.

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Phytophthora AerialBlight, Crown Rot,and Root Rot

The soilborne fungusPhytophthora nicotiana (formerlyP. parasitica) can cause foliarblight and crown and root rot ofpansy. Wet conditions are neces-sary for this fungus to be active incausing disease. In the case ofroot rots, research has shown thatdrought or excessive applicationsof fertilizer will result in increasedsusceptibility to Phytophthora.Both aboveground and below-ground phases of the disease maybe present on landscape orgreenhouse pansies, but foliar dis-ease is more prevalent on land-scape plants, while crown androot rot diseases are morecommon on pansies in green-house production.

Foliar blight or aerial blightoften develops at temperatures of75 to 85 degrees F when humiditylevels are high and foliar moistureis abundant. Reports indicate thatthis disease develops rapidly attemperatures of 82 degrees F andhigher. Leaves and stems oninfected plants develop water-soaked spots that are light brownin color. Spots are irregular inshape and spread quickly toinvolve large areas of the plant.(Figure 9). When wet conditionsoccur, lesions girdle stems andfoliage blight involves large por-tions of the plant. Drier condi-tions typically slow diseasespread. Death of plants usuallyresults from a combination ofdieback from girdled stems andspread of foliar leaf blight.Splashing water droplets easilyspread the disease. Spores mayalso be carried to other plants bywater movement in the soil.

Control of aerial blight in thelandscape involves removal ofdiseased plants and plant debris,reduced or adjusted irrigationpractices, and planting in areaswhere soils drain well. Fungicide

resemble Pythium crown and rootrot. In some situations,Phytophthora may cause a water-soaked rotting of tissues that hasa darker brown discoloration andis easier to visually detect thanwith Pythium. Pulling on theouter cortex, as was describedearlier for Pythium crown androot rot, can reveal tissue deterio-ration. Confirmation of Phytoph-thora or Pythium crown and rootrot often requires laboratorytesting. As root and crown rotprogresses, foliage usuallydevelops wilt and dieback.Stunting and yellowing may alsoresult from crown and root rotcaused by Phytophthora.

Control of Phytophthoracrown and root rot in the land-scape or greenhouse is the sameas for Pythium. See Table 6 forfungicides labeled for control ofPhytophthora crown and root rot.Pythium and Phytophthora arevery similar fungi in manyrespects, and many fungicidesthat are labeled for Pythium arealso labeled for Phytophthora.

Rhizoctonia FoliarBlight, Crown and Root Rot

The fungus Rhizoctoniasolani causes foliar blight andcrown and root rot diseases ofpansy. This fungus is not as com-monly seen as the fungi men-tioned previously, but it doesoccasionally cause problems.High humidity and moisture favorthe foliar phase of the disease;moderate soil moisture favors thecrown or root rot phase. Foliarblight appears as brown, some-what dried lesions on stems andas spreading brown lesions onleaves (Figure 10). Blight mayinvolve large portions of theleaves and stems. Girdled stemsresult in complete plant collapse.When conditions are humid, afine fungal webbing may developand eventually cover portions ofthe blighted tissues.

application is not usually recom-mended in landscapes unless thedisease occurs on young plants inlarge plantings. Diseased plantsshould be removed as soon aspossible after discovery. Careshould be taken to remove wholeplants, including roots as well asthe associated soil. Removedplants should be placed in a bagat the location of removal to pre-vent contamination of otherplants in the bed. If possible, soildrainage in the area should beimproved. Irrigation practicesshould be modified to reduce thetime that foliage remains wet.When appropriate, the length ofirrigation periods should also bereduced so that soil does notbecome overly saturated for pro-longed periods. See Table 6, iflarge plantings are involved andprotective fungicide use isdesired. Unfortunately, recenttesting has shown that none ofthe fungicides currently availableprovide 100 percent disease con-trol under conditions favorablefor disease spread.

In a greenhouse situation, dis-ease control requires removal ofdiseased plant material, takingcare not to contaminate healthyplants with diseased plant parts orpotting media. Benches, trays,pots, and tools must be washedthoroughly and treated with agreenhouse disinfectant beforereuse. For many greenhouse situ-ations, replacement of plug flatsand flats is recommended ratherthan attempting to clean and dis-infect these items. Irrigationschedules should be reviewedand adjusted to reduce the pres-ence of excess water. Fungicideapplications will give some pro-tection against disease spread. SeeTable 6 for fungicides labeled forcontrol of Phytophthora foliageblight in a greenhouse.

The crown and root rot phaseof Phytophthora, which may becaused by P. nicotiana or otherspecies, produces symptoms that

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Diseases of Pansies and Their Control 7

Table 6. Pythium Root and/or Collar (Crown) Rot; Phytophthora Aerial Blight and/or Root/Collar Rot

Fungicides Rates Commentsper gallon per 100 gallons

etridiazoleTruban 30W —- 4 to 6 oz Soil Drench: 100 gallons of fungicide mixture covers 800 Truban 25E —- 3 to 4 fl. oz. square feet of bench or bed area. Irrigate immediately and

repeat at 1- to 2-month intervals.fosetyl-AlAliette T/O —- 1.25 to 4 lb. Foliar Spray: Apply to wet foliage, using no more than 400

gallons of spray volume per acre treated. Repeat as needed at monthly intervals.

menfenoxanSubdue Maxx —- 0.13 to 0.25 fl. oz. Drench at Seeding: 100 gallons of mixture covers 400 to

800 square feet of bench or bed area. Reapply after 1 to 2 months.

—- 0.5 to 2.0 fl. oz. Drench at Transplanting: 100 gallons of mixture covers 400 to 800 square feet of bench or bed area. Reapply after 1 to 2 months.

Subdue GR —- 1.6 to 8 oz. per Dry Soil Mix: Mix thoroughly and irrigate with enough cu yd of mix water to wet the root zone.

propamocarbBanol 66S —- 30 fl. oz. Drench at Seeding and Transplanting: Apply 3 quarts of

mixture to 10 square feet of bench or bed area.thiophanate-methyl + etridiazoleBanrot 40W —- 4 to 8 oz. Soil Drench: 100 gallons of fungicide mixture covers 800

square feet of bench or bed area. Irrigate immediately and repeat at 1- to 2-month intervals.

Banrot 8G —- 8 oz. per cu. Dry Soil Mix: Mix thoroughly. Reapply soil drench yd. of mix as needed.

Control of this disease in thelandscape requires removal ofinfected plants. Care should betaken not to spread diseasedplant material. If large plantings ofpansies are involved, protectivefungicide spray treatments maybe appropriate. See Table 7 foravailable fungicides. Follow labeldirections.

Disease control in the green-house is much the same as thatdescribed for the landscape.Diseased areas, trays, and toolsshould be sanitized by treatingthem with a greenhouse disinfec-tant. In many situations, it is rec-ommended to replace plug flatsand flats rather than attempt tothoroughly disinfect these items.See Table 7 for labeled fungicides.

The crown and root rot phaseof the disease develops as brownsunken lesions on lower stems(crowns) and roots. Decay is usually characterized as dry rot.

As the disease progresses togirdle the crown and involvemore root area, abovegroundparts of the plant become stuntedand yellowed, exhibit dieback,and eventually wilt and collapse.In some situations, girdled crownsmay become brittle, and foliagemay easily break off from theroots at the decayed crown(Figure 10). This type of deterio-ration at the crown may also becaused by other crown rotpathogens.

Disease control in the land-scape and greenhouse requirespractices of plant removal, disin-fection, and tray replacement sim-ilar to methods described for theaerial phase of this disease.Excess nitrogen should not beapplied because it favors diseasedevelopment. Fungicides shouldbe applied as protective drenchesin greenhouse plantings or in

large scale landscape plantingswhen the disease develops earlyin the season. See Table 7 forfungicides labeled for control ofRhizoctonia crown and root rot.Always follow label directions.

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Table 7. Rhizoctonia Aerial Blight and Root and Collar Rot

Fungicides Rates Commentsper gallon per 100 gallons

azoxystrobinHeritage 50W —- 1 to 4 oz Heavy Spray/Drench at Transplanting: Apply enough water to

wet foliage of target plant and media around base of plant.Reapply as needed. Use higher rate at shorter interval whenconditions favor disease.

iprodioneChipco 26019 50W —- 1 to 2 lb. Drench at Seeding or Transplanting: Apply 1 to 2 pints of

fungicide suspension per square foot of bench or bed area.Reapply every 2 to 4 weeks as needed.

thiophanate-methyl3336 50W —- 12 to 16 oz. Apply as a drench to the media or soil around base of plant 3336 4.5F —- 16 to 20 fl. oz. before symptoms are seen. Reapply as needed every 1 to 2

months. Shorten interval and increase rate when conditionsfavor disease.

thiophanate-methyl + etridiazoleBanrot 40W —- 4 to 8 oz.

trifloxystrobinCompass 50W —- 2 to 4 oz.

triflumizoleTerraguard 50W —- 2 to 4 oz.

ANR-1214

Jackie Mullen, Extension Plant Pathologist and Diagnostician, and Austin Hagan,Extension Plant Pathologist and Professor, Entomology and Plant Pathology, both atAuburn University

Use pesticides only according to the directions on the label. Follow all directions, precautions, and restrictions that arelisted. Do not use pesticides on plants that are not listed on the label.

The pesticide rates in this publication are recommended only if they are registered with the Environmental ProtectionAgency and the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listedhere is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latestinformation.

Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse orguarantee any product and does not recommend one product instead of another that might be similar.

For more information, call your county Extension office. Look in your telephone directory under your county’s name tofind the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, andother related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System(Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employmentto all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

UPS, 6M41, New Sept 2001, ANR-1214

Figure 8. Pythium crown and rootrot of pansy Figure 9. Phytophthora foliage blight

on pansy

Figure 10. Rhizoctonia crown rot (aswell as crown rots caused by otherpathogens) may result in stem breakage.

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