Common Peach Diseases

CommonPeachDiseases

JaneE.StewartPlantPathologist

ColoradoStateUniversity

Coloradoclimateinhibitssomepathogens,andotherpathogenbehavedifferently

FoliarPeachDiseases• Brownrot• Peachleafcurl• Shothole*• Powderymildew*

Stem/RootPeachDiseases• Armillaria rootrot*• Phytophthora rootrot• Cytospora*

*ImportantColoradoDiseases

Brownrot• Fungalpathogen:

Monilinia fructicola

• No.1diseaseinSoutheast,butwidespreadinUS

• Hostsinclude:Prunus spp.

• Typicallyoccursinareaswithhighmoisture

• Polycyclicdisease

Chavez,UGA

BrownRotSymptoms

• Blossomblight,twiganddiebackandfruitrot

• Someinfectionsaresymptomlessuntilfruitripens

• Symptomsmayoccurwhileinstorage

PNWhandbooks.org

IdentificationofBrownRot

• Mummyberries

• Sporulation– Lookforapotheciainwinter/earlyspringinmoistareas

– Iffound,infectionsarelikelytobehigh

Intermountainfruit.org

APSnet.org;Sanoamuang &Ganut

DiseaseCycleofBrownRot

Winter

Spring

SummerandFall

Protectivefungicidestopreventnewinfections



M.Ellis,OSU

ManagementforBrownRot• Sanitation:Removeinfectedfruits– Limitsinoculumcurrentandnextgrowingseason

• Controlinsectdamageandwounding

• Postharvest:coolfruitrapidlyafterharvest– Shortsoakin122Fwater

APSnet.org

ChemicalManagementforBrownRot

• Fungicidesarethebestoption– SterolInhibitors:Indar,Elite,PristineandGem– Iprodione:Rovral – Springapplication– Copperorsulfur

• Sprayatfullrateandcoverageatpinkbud,fullbloomandpetalfall

• Wetconditions:7-10dayspost

• Rotatefungicideclasses

• Populationsarebecomingresistanttosterolinhibitorfungicides

PeachLeafCurl• Fungalpathogen:Taphrina deformans

• Hosts:Peach,plum,nectarine,almond

• Candefoliatetreesearlyintheseason

• FoundthroughouttheUS

SymptomsofPeachLeafCurl

M.A.Hansen,VATech

DiseaseCycleofPeachLeafCurl

Healthyanddiseasedpeach

Sporesoninfectedleafandfruit

Sporespenetrateshosttissues

Spores

NewInfectionsonyoungleaves

Sporesoverwinteronbudsortwigs

Winter

Spring SummerandFall


Agrios

ManagementforLeafPeachCurl

• Fungicidesarethemosteffectmethodofcontrol

• Asingleapplicationbeforebudsbegintoswellcancontroldiseaseforaseason

• Canalsoapplychemicalsindormantseason– Ferbam,Ziram,Chlorothalonil,orcopper

Shotholeblight

• Fungalpathogen:Thyrostoma carpophilum(Wilsonmyces carpophilus)

• Hosts:Peach,apricot,cherry

• CommoninIntermountainWest



Symptomsofshothole


UtahStateUniversityExtension

Diseasecycleforshothole

Winter

Infallandwinter,sporesareproducedduringwetconditions

Sporescaninfecthealthytissues.

Inwarm,dryweatherfungussurvivesinbudsandtwigsuntilwetweatherreturns

Inspring,sporesaredisseminatedviawind/rain


SummerFall


Laterinspring,sporesinfectfruit

Spring

Fungusoverwintersininfectedbudsandlesionsonsmallshoots

UtahStateUniversity,Extension

CulturalControls• Summerrainandsprinklerirrigationpromotefruitinfections,whenfruitiswetforlongerperiodsoftime

• Iforchardissprinklerirrigated,reducecanopywetnessbyadjustingsprinklers

• Prunecankersandremove/burninfectedbranches

Chemicalcontrolsforshothole

• Similartoleafpeachcurlandbrownrot

• Bordeauxmixture,Boscalid,Chlorothalonil,Azoyxstrobin

• Inorchardswithahistory,sprayatleaffalltoprotectagainsttwiginfections

• Springapplicationsduringbloomandwetconditionstopreventfruitandleafinfections.

PowderyMildewsonPeaches

• Fungalpathogens:Podosphaera pannosa– Infectspeachandrose

• Podospharea leucotricha– Infectsapplesandpeaches


• Obligatepathogen


SymptomsofPowderyMildew• Yellowingordistortedleaves

• Stuntedshootgrowth

• Reducedyield

• Powderyresidueonleavesandfruit


Identification

• Conidia

• Cleistothethia

Apsnet.org

DiseasecycleofPowderyMildew

• Overwintersoninbuds,asbudsexpand,infectionoccursonyoungleaves

• Sporulationoccursusuallyatnightwithrelativehumidityishigher

• Sporegerminationoccurswhentemperaturesarebetween36-98F.

APSnet.orgH.Larson

ManagementofPowderyMildews• Providegoodcirculationbypruningforincreaseairflow

betweentrees

• Fullsunexposure

• Uselowerlevelsofnitrogen– lesssucculent,younggrowth

• Removenearbyroseforpeachpowderymildew

• Donotplantpeachesnexttosusceptibleapplevarieties– Gala,Jonathan,MacIntosh,RomeBeauty

H.Larson

ChemicalControlforPowderyMildew

• Conventional:Azoxystrobin (Abound),boscalid +pyraclostrobin (Pristine),thiophanate methyl(Topsin)

• Organic:Potassiumbicarbonate+horticulturaloil,sulfurbased

• Sprayearlyspring(7-10days)untilsymptomsaremoderate

• Alternatechemicalstopreventfungicideresistance

H.Larson

Stem/RootPeachDiseases• Armillaria rootrot*• Phytophthora rot• Cytospora*

*ImportantColoradoDiseases

Armillaria RootRot

• Fungalpathogen:Armillaria mellea

• Hosts:Manyhardwoods

• Persistsondecayingrootsanddebris,infectsnew

• OccupieslargeareasGuidoSchnabel

Humongousfungus

Symptoms• Heightgrowthisreduced

• Thincrown

• Yellowleaves

• Sapontherootcollar

• Reducedrootsystem

• Circleofdiseasedtrees

Identification

Honeymushrooms

Mycelial Fans

Rhizomorphs

Conditionsthatpromotedisease• Poorlydrainedsoilsandexcessirrigation– Furrowirrigatedorchards

• Areasoflowerelevationafield

• Plantingnewstockinthesameareas

RootstockWorkingGroup,rootstocks.net

CulturalManagementOptions

• Avoidexcesswatering

• Armillaria canexistsformanyyears;Sanitizetoremovediseasedrootsbeforereplanting

• Avoidwoundingroots;Shadeexposedcrownsfromsunburn

• Rootcollarexcavationtoexposecrownstoairandtolimitspreadtothestem

• Keeptreeshealthy

Rootcollarexcavation

GuidoSchnabel,ClemsonUniversity

Phytophthora RootCrownandCollarRot

• Causedbypathogens:Phytophthora cactorumandPhytophthora spp.

• Hosts:Peach,apple,cherry,apricot

• Soilborne pathogensT.Burr,Cornell

SymptomsofPhytophthora RootRot

• Stuntedgrowth

• Scorchedleaves,dryleavesthatremainontree

• Reducedrootsystem

• Circleofdiseasedtrees

T.Burr,Cornell

IdentificationofPhytopththora rootrot

M.Murray,UT

OosporesofP.cactorum,Cating etal.2010

DiseasecycleofPhytophthora rootrot

Insoilandrootsresistantstructure

Optimumtemperature50-60ºF

Swimtotheroottips–optimumtemperature50-64ºF

Severalhundredoosporescanbeproducedperinchlengthofinfectedroot!!

Penetrateroot

WolfgangOßwald etal.2004

ManagementofPhytophthora RootRot• Avoidexcesswatering,especiallyinthefallandspring.

Goodtemperaturesforfungalinfectionandlessusebythetree

• Planttreesonagoodsite.Gooddrainageandevenlysloped

• Planttreesshallowonamound

• Moveeasilyonnurserystocksoensurecleanmaterial

• Selectresistantrootstocks

• Soildrenchesofmefenoxam (Ridomil Gold)

CytosporaCanker

• CausedbyCytospora spp.

• Commononallstonefruitsandmanyothertreespecies(urbanandforests)

• Associatedwithstress(drought,pH,colddamage)

• MostsignificantdiseaseinColoradopeaches

CytosporaDiseaseCycle• Fungusgrowsinbarktissuethrough

openwounds,andcancanalsoenterbuds

• Killsbygirdlingbranchesortrunkoftree

• Attackstreeduringconditionswhentemperaturesarewarmandmoistureisavailable

• Treesaffectedbydrought,latespringfrosts,insectandfungidefoliation,sunscald,herbicides,ormechanicalinjuryaresusceptibletoCytosporainfection

AlanBiggs

SurveyofOrchards

• EstimatedincidenceandseverityofCytospora inmajorpeachproductionareasofWesternColorado

• March/April2015

• ConductedinGrandValley,NorthForkandOlatheareas– Focusongatheringdatafromawidespreadareaandrangeoforchardmanagement

Methods• Surveyedbyorchardandvariety

• Recordedpresence/absenceforevery10th tree

• Countedandratedinfectionseverityforevery50th tree

• Interviewedgrowers• CollectionsofCytosporaisolates

K.Kimbrough

Results• Surveyed:

– 200acres– 42varieties– 2-32yearoldorchards(11yr mean)

• 100%oforchardssurveyedinfected(mean75%infected)

• Avenumberofinfectionspertreewas5.2(range0-27)

• Potentialrelationshipsbetweenpracticesandinfection,butareinconclusiveatthistime

Speciesdifferbiologically

• ThreespecieshavebeenidentifiedonpeachwithintheUS:– Cytosporaleucostoma– Cytosporaparaleucostoma– Cytosporacinctum

• Only1specieshasbeenidentifiedinColorado– Cytosporaleucostoma

SymptomsofCytosporacanker

Larson&Pokharel

IdentificationofCytospora

Diseasecycle

Funguspersistsandformsfruitingstructuresindeadwoodandcankers

Conidiaspreadbyrain;germinateandinfectinjuredanddeadtissues,expandsascankers

Humid,wet

Leafscars,damagedbuds

Crotcheswithnarrowbranchangles

Shadedwinterdamagedtwig

Unhealedpruningstub

Poorlyhealedwound

BiggsandGrove2006.

Cankerringsformedbyinfectionandhostcallusformation

Highinoculationlevelscorrelatedwithhighrainfallevents(Watapo,WA)

GroveandBiggs2006.PlantDisease

1993 1994 1995

Spreadofsporesfromcankers

GroveandBiggs2006.PlantDisease

� Maximumspread2ft fromrainsplash

� Moreinoculumfurtheratangleshigherthan90degreesfromcanker

� Rainsplashisimportantforinoculumspread

� Aretherelongdistancespreadmechanisms?� Wind� Insects� Humans

Healthytrees• Tohelpatreeresistinfection:– Preparesoilbeforeplanting– Fertilize,waterproperlyforwinterandsummer– Avoidinjurytothetrunkandlimbs– Prunecorrectly

• SlowgrowthinFall:– Fertilizeinlatewinterorearlyspring– Avoidexcessivenitrogenfertilization,whichcausesvigorousgrowth

– Treesneedtohardenoffinfalltopreventcold-injury

ManagementTools

• Managetreestress

• Removecankers– Pruning

• Reduceinoculumlevels– Pruning– Chemicaltreatments

ChemicalManagementoptions

Stephanwillpresentthese!

Summaryfoliarfruitdiseases

SummarysoilbornepathogensArmillaria RootRot

Phytophthora RootRot

T.Burr,Cornell

Avoidexcesswatering, planttreesonagoodsite,plantshallowonamound,usecleannurserystock,resistantcultivarsinavailable,drenchwithmefenoxa

Avoidexcesswatering,sanitizesitesbeforereplanting,avoidwoundingroots,rootcollarexcavationmethod,keeptreeshealthy

Questions?

Documents

Common Peach Diseases