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Permanent Link: http://ufdc.ufl.edu/IR00002377/00001
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Title: Control Of Insects, Mites And Diseases Of Florida's Dooryard Citrus Trees
Physical Description: Fact Sheet
Creator: Knapp, Joseph L.
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla
Publication Date: 1994
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Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status: Published
General Note: "Publication date: May 1992. Reviewed: August 1993. Revised: June 1994."
General Note: "Circular 139"
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Source Institution: University of Florida Institutional Repository
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Circular139 June1994ControlofInsects,MitesandDiseasesofFlorida'sDooryard CitrusTrees1 JosephL.Knapp2Insects,mites,anddiseasesarecommonproblems totheFloridahomeownerwithadooryardplantingof citrus.Theobjectofthiscircularistoaidhiminthe controlofthesepests. Frequently,moreharmthangoodcomesfroman attempttocontrolthesepestswithpesticides.Tobe successful,the rightmaterial shouldbeappliedatthe righttime usingthe rightamount inthe right manner.Ifanyoftheseconditionscannotbemet,it isusuallybetternottosprayatall. Inordertoacquaintthehomecitrusgrowerwith insects,mites,anddiseasesandtheircontrol,the subjectsarediscussedinthefollowingorder: individualproblems;beneficialinsects,mites,and fungi;approachestothecontrolofcitruspests; dooryardpestcontrolchart;suggestedspray programs;sprayers;andprecautionsintheuseof pesticides.INDIVIDUALPROBLEMS MitesCitrusrustmites haveanannulate,wedge-shaped body,lemon-yellowincolorandabout1/200inchin length.Theyhave2pairsoflegsandpiercing-sucking mouthparts.Theycanjustbarelybeseenwiththe nakedeyeandcanbeseenbetterwitha10-power magnifyingglass. Thelifecycleofthecitrusrustmiteiscompleted within5-7daysduringthesummer.Eggsare spherical(round),transparent,andlaidsinglyon leaves,stems,andfruitofallcommercialcitrus varieties.Themitehas2immaturestagesthatare similartotheadultinappearance.Althoughpresent throughouttheyear,inFloridathecitrusrustmiteis mostprevalentduringthesummermonths. Injuryfromextensivecitrusrustmitefeeding causessurfaceblemishtothefruit.Thiscanreduce theexternalqualityofmarketablefruit,andreduce yieldbycausingprematurefruitdropandreduced fruitsize.Noneoftheseaffectstheinternalfruit quality. Citrusredmites(purplemites) areonlyabout 1/50inchlong.Theyarebrightredtodeeppurplein colorandinfestleaves,fruit,andnewgrowth.Injury resultsfromfeedingandappearsasascratchingor etchingoffruitandtheuppersurfaceofleaves.In periodsofprolongeddryweather,theycancausea collapseofleafcellsandevenleafdrop.Usea10X magnifyingglasstoinspectforcitrusredmitesand 1.ThisdocumentisCircular139,aseriesofthePestManagementDepartment,CitrusResearchandEducationCenter,LakeAlfred,FL, FloridaCooperativeExtensionService,InstituteofFoodandAgriculturalSciences,UniversityofFlorida.Publicationdate:May1992. Reviewed:August1993.Revised:June1994. 2.JosephL.Knapp,professor,entomologist,DepartmentofEntomologyandNematology,CitrusResearchandEducationCenter,Lake Alfred,Florida,abranchcampusoftheUniversityofFlorida,Gainesville,Florida. Theuseoftradenamesinthispublicationissolelyforthepurposeofprovidingspecificinformation.Itisnotaguaranteeorwarrantyofthe productsnamed,anddoesnotsignifythattheyareapprovedtotheexclusionofothersofsuitablecomposition. TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,Dean

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page2eggsontheuppersurfaceoftheleaf,looking especiallyalongthemidrib,aswellasinangular crevicesoftheleafstemsandtheyoung,tendertwigs. CitrusredmitesaremorenumerousfromMay throughJuly,butcanbethemostdamaginginthefall andwintermonthsduringperiodsoflowrainfallor inadequateirrigation. Texascitrusmites areaboutthesamesizeas citrusredmites,butarebrownish-greenincolorwith darkbrowntogreenishspotsorbarsnearthelateral margins(edges).Numbersofmitesaregenerally muchheavieralongthemidribontheuppersurface ofleaves.TheyalsoaremostnumerousMaythrough July,andmostdamagingOctoberthroughFebruary. Six-spottedmites arealsoaboutthesamesizeas citrusredmitesbutarewhite-yellowtosulfur-yellow incolor.Adultsusuallyhavesixdarkspotsthatare barelyvisiblewitha10-powermagnifyingglass, arrangedintworowsonthebackorabdomen.These mitesliveincoloniesontheundersurfaceofleaves, especiallyalongtheveinsandmidribs.Injuryappears asyellowspots,oftencuppedtowardthetopofthe leaf.Six-spottedmitesprefergrapefruit,butcanbe foundoccasionallyonothervarietiesofcitrus.They usuallyappearinearlyFebruaryandhave disappearedbymidJuly.InsectsPurplescale and Gloverscale (longscale)are verysimilarinappearanceandhabits,butGlover scaleislongerandnarrower.Thecoveringofthe maturescaleispurplish-brownincolorandabout1/8 inchlong.Thesescalessuckjuicesfromleaves,fruit, twigs,andbranches.Injurytoleavesresultsinyellow orchloroticspots.Thesescalescancauseleavesand fruittodrop,aswellascausetwigsandbranchesto die.Theyareoftenoverlookedbecausetheyare foundprimarilyontheinnerpartsofthetree. Chaffscale formsalightbrown,nearlyround armorcloselyresemblingapieceofwheatchaff. Whereabundantonthebark,thelimbsappeartobe coveredwithchaff.Thisscaleinfestsleaves,fruit, andbark,causinggreenspotsonthefruit. Citrussnowscale isapestinmostpartsofcitrus growingareasofFlorida.Malescaleshaveelongated whitearmor,whilefemalesaremahoganycolored, makingtheminconspicuousandhardtoseeagainst treebark.Theyarelargelyconfinedtothetrunk, limbs,andtwigs. Ifitsparasiteisnotactiveinyourarea,chemical controlmaybenecessary.Besuretothoroughlywet allinfestedbark. FloridaRedscale and Yellowscale arearmored scalesofsimilarsizeandshape.Thearmoror coveringoftheadultfemaleisalmostcircularin outlineforbothscales;however,theyellowscaleis yellowtolightorangeincolor,whileFloridaRed scaleisdarkreddish-brownwithanipple-shaped centerthatisgrayishtoreddish-yellow.Theseinsects infestleavesandfruit,andcancausethemtodrop. DonotmistakeFloridaRedscaleforfungus killedwhiteflies. Cottonycushionscaleisrarelyofeconomic importanceexceptinnurseriesandonyoungtrees. Thematurefemaleisconspicuousbecauseofher flutedwhiteeggsac.TheVedalialadybeetlefeedson thisscaleandusuallykeepsitundercontrolbut cannotalwaysbedependedupononyoungtrees. Whiteflies primarilyattacknewgrowth.The nymph(immaturestage),whichistransparentand seldomrecognized,infeststheundersideoftheleaves, withdrawingcopiousquantitiesofsap,resultingin someinjurytothetrees.Dooryardgrowersalso objecttosootymoldfungus,whichinturngrowsin thehoney-dewexcretedbytheimmaturestagesofthe whitefly.Neverspraythetreeswhenalargenumber ofadultwhitefliesarepresent.Instead,wait10to12 daysuntilmostoftheadultwhiteflieshave disappeared.Thiswillallowenoughtimefortheeggs tohatchandtheyoungtobekilledbeforetheycan causemuchdamage. Thecitrusblackfly isacloserelativeofthe commonwhiteflyoftenseeninFlorida.Theadultfly isabout1/25ofaninchlongandslateblue-blackin color.Eggsarelaidinadistinctivespiralpatternon theundersideofleaveswithabout28to34eggsin eachspiral.Thelarvaechangefromduskycolor throughdarkbrowntoblackastheygrow.The pupaeareshinyblack,spiny,andovalinshape. Homeownersshouldlookforthisinsectonthe undersideofleavesandreportsuspectedinfestations tothelocalcountyExtensionoffice. Mealybugs haveasegmentedbodywhichis coveredwithmealywhitewax.Theyaremost commonduringthespringandearlysummer,butare frequentlyfoundduringthewinterintreecrotches andunderloosebark.Mealybugsmaybecomeso

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page3numerousfollowingfruitsetthattheirfeedingunder thebuttonofyoungfruitmaycausethefruittodrop. Theyalsocollectinmassesbetweenfruitclusters. Sootymoldcanalsobeseverefollowingamealybug infestation. Aphids orplantliceattackyoung,tendergrowth andcauseleavestowrinkleandcurl.Insecticides shouldbeappliedtoinfestedyounggrowth beforethe leavescurl. Thereislittlevalueinapplyingan insecticideaftermanyleavesarecurledornewgrowth isnearlymature. The orangedog isoftenapestofyoungcitrus trees.Asanadult,thespeciesisalargeblackand yellowswallowtailbutterfly.However,itisnamed fromthelarva,whichisanuglybrownandwhite caterpillarwhichgrowstoalengthof11/2to2 inches.Duringthesummerandearlyfall,these caterpillarsmaybequitedestructiveonyoungtrees. Pickcaterpillarsoffyoungtreesbyhand. Severalkindsof grasshoppers and katydids feed ontheleavesofcitrustrees,butusuallyarenot importantpestsofdooryardtrees.Eggsofthebroadwingedkatydidarelaidalongtheleafmarginsand arousetheinterestofmanyhomegardeners.SOMEBENEFICIALORGANISMSTherearemanybeneficialparasites(tiny,wasplikeinsects),predators(insectandmite)and pathogens(predominantlyfungi)thatattackvarious pestsofcitrus.Inmanycases,naturalenemies regulatepotentialpests.Thisisreferredtoas biologicalcontrol. Parasiticwasps.Manywasp-likeparasites, particularlyofthegenus Aphytis,effectivelycontrola widerangeofarmoredandsoftscalepests.Most noteworthyaretheparasitesofpurplescale,Florida Redscale(Plate33),andcitrussnowscale. Fungi. Twoparasiticfungi,Aschersoniaspp.and Aegerita sp.arecommonlyfoundinfectingimmature whitefliesofcitrus.Red Aschersonia formspinkand reddishpustules1/8inchorlessindiameteronthe undersideofleaves.Itissocolorfulthatmany growersarequiteconcernedwhenitappearsand usuallythinkitisharmful. Aegerita orbrownwhitefly fungusappearsascinnamonpustulesabout1/8inch indiameterontheundersideofleaves.Thisfungus isoftenconfusedwithFloridaRedscale. Otherfungisuchas Hirsutellathompsonii and Triplosporiumfloridana attackcitrusrustmiteand Texascitrusmite,respectively.H.thompsoniiis particularlyimportantinreducingcitrusrustmite populationsinthesummer. Predators. Severalinsectandmitepredatorssuch astheladybeetles(adultandlarvae)andlacewings (larvae)feeduponeggsandotherstagesofinsects andmites.Mostaregeneralintheirfeedinghabits andexhibitanoveralleffectonpeststhroughoutthe year.DISEASESScab isafungusdiseasethatattacksyoungleaves, smallfruit,andtendertwigsofgrapefruit,Temple, Murcotthoneyorange,lemons,sourorange, Satsumas,andsomevarietiesoftangelos.Itcauses raised,lightbrown,corkyareasonfruitandleaves. Melanose isafungusdiseasethatattacksyoung fruitprimarilyofgrapefruit,however,othercitrus varietiesmaybeaffected.Theinjurytofruitisoften confusedwithrustmiteinjury,whichhasasmoother feel.Thisrindblemishdoesnotaffectthequalityof thefruit.Whilescabismoreimportantonyoung trees,melanoseismoreinjurioustooldertrees. Treesareusuallyover10yearsofagebefore melanosebecomesaproblem.Sincemelanosegrows indeadwood,keepingthetreesfreeofsuchwood willaidinthecontrolofthisdisease. Greasyspot isafungusdiseasethatattacksall varietiesofcitrusgrowninFlorida.Infectionoccurs mostlyinthesummer,butsymptomsdonotappear untiltwotoninemonthslater.Symptomsfirstshow upasyellowish-brownspotsontheleaves.Thespots developaslightlyblisteredappearanceonthe undersideoftheleaves,andultimatelybecomeoily brownorblack.Spotsvaryinsizefromsmalldotsto 1/4inchindiameter.Whereseveralspotscoalesce (growtogether),theareascoveredmaybe considerablylarger.Thisdiseasecancauseserious prematuredefoliationduringthewinter.Thisdisease mayalsoinfectthefruitrind,especiallyongrapefruit, causingspeckstoappearinareasbetweentheoil glands. Goodspraycoverageofthelowerleafsurfaceis essentialforsatisfactorycontrol. Sootymold mayblackenleavesoftheentiretree. Aphids,mealybugs,certainsoftscales,and

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page4particularlyimmaturewhitefliesexcreteasweet, syrupymaterialknownashoney-dew.Thesootymold fungusgrowswhereverthismaterialfalls.Controlling theseinsectswillpreventsootymold,andoilsprays willusuallycauseittoflakeoff,makingtheleaves andfruitbrightandshiny.APPROACHESTOTHECONTROLOF CITRUSPESTSHomeownerswithafewcitrustreesshouldfollow oneofthefollowingcoursesinthecontrolofinsects anddiseases: 1. Donotapplypesticides. Dependentirelyon naturalcontrolofpredaceousinsectsandmites, parasiticinsectsanddiseases,weather,andother factors.Therearemanyinstanceswhere dooryard,andevencommercialplantingsare neversprayedordusted,andyetthetreessurvive andproducegoodcropsofsatisfactoryfruit. Underthisprogram,yieldmaybereducedand externalqualitywillusuallybelow. 2. Controlindividualproblemswhentheyfirst appear. Makefrequentinspections,identifythe problems,andapplytherecommendedpesticides beforeinfestationscanbecomesevere.These stepsrequire:1)learningtoidentifythemore commonpestsofcitrus;2)detectingtheir presenceearly;3)spraystimedtogiveeffective control.Unfortunately,mosthomeownersdonot findthispracticeeasytofollowandtheresults areoftenunsatisfactory.Frequently,thepests causeseveredamagebeforetheyaredetected. 3. Followthesprayprogramsuggestedinthis circular. Thisschedulemayneedtobe supplementedintheeventinsectssuchas grasshoppers,katydids,andotherlesscommon pestsattackcitrustreesbetweentheregular sprays.SuggestedSprayProgramThereisnosimpleruleonecanfollowwhichwill alwaysresultinbrightfruitandvigoroustrees. However,thereisarathersimplesprayschedulethat canbefollowedwhichwillcontrolmostpestsand resultinthriftytreesproducingfruitofgoodquality, butnotnecessarilyalwaysofabrightcolor.A scheduleofthistypeusuallyrequiresthreeorpossibly foursprayapplicationsperyear.Asuggestedspray programfollows.(Substitutescanbemade-see Table1.) Postbloom(4weeksafterpetalsfall)-Copper plusarecommendedmiticide. Summer(July)-BenlateorcopperplusEthion plus.5%sprayoil. Fall-Recommendedmiticideforcitrusrustmite andspidermitecontrol.SprayersManyofthefailurestocontrolcitruspeststhat arechargedagainstthepesticidearequiteoftenthe resultof improperapplicationandtiming. A gardenerwhohasasubstantialnumberofcitrustrees isadvisedtogetagoodsprayer.Onetothree-gallon compressedairmodelscanbeusedwhiletreesare small.Thesemodelsarenotexpensive.Airpressure ispumpedupbyhand,andthenozzle,whichisatthe endofashortwand,deliversafinespraywhichcan beaccuratelydirectedtoallsurfaces. Whentreesbecomelargeandcannotbe thoroughlycoveredbythistypeofsprayer,dooryard citrusgrowersshouldeitherobtainasmallpower sprayerorhiresomeonewithadequateequipmentto insurethoroughcoverageoftheentiretree.Ifthese conditionscannotbemet,itisgenerallybetternotto applyspraysatall. Sprayerswhichattachtotheendofgardenhoses aregenerallynotsatisfactoryforuseonmaturecitrus trees.Thespraypatternisusuallycoarse,anditis verydifficulttodirectthespraytoreachand adequatelycovertheundersidesoftheleaves, especiallythoseneartheground,andthesideof plantsclosetoabuildingorfence.Ifahose attachmentsprayerisused,theemulsionconcentrate formulationofinsecticideispreferredoverthe wettablepowder.PRECAUTIONSINTHEUSEOFPESTICIDESCareinHandlingPesticides. Treatallpesticides aspoisonsandhandleaccordingtothecautionson themanufacturer'sproductlabels. Alwaysreadthe label carefullyandcompletelybeforeusingany pesticide. PesticideResidues. Citrusconsumedbythe producershouldbepreparedbythegenerally

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page5acceptedpracticesofwashing,peeling,etc.Dooryard fruitthatisofferedforsalemustconformwithfederal and/orstatefoodanddrugpesticideresidue regulations.Copperandoilemulsionsareexempt fromatolerance,andnowaitingperiodisrequired. Waitingperiodsbetweenlastapplicationofcertain pesticidesandharvestoffruitareasfollows:Benlate -notimelimitation;Ethion-21daysonlemonsand limes;notimelimitationonorange,grapefruit, tangelo,tangerine;donotrepeatapplicationwithin90 days;Kelthane-7days;Malathion-7days. OilEmulsionSprays. Donotapplyoilemulsion spraysduringthefallorwintermonthsortoatree thatshowssignsofwilting.Allowatleast6weeksto elapsebetweenapplications.Donotmixoilwith sulfur.Applythetwoseparately,allowingatleasta three-weekintervalbetweenapplications,orinjuryto fruitandfoliagemayresult. Herbicides (weedkillers).Anotherproblemthat shouldbeofconcerntodooryardcitrusgrowersisthe useofweedkillersonlawns.Ifaweedkillerisused, besureitisnotusedcloseenoughtocitrustoresult inresiduesinthefruit;orbesureitisapprovedfor usearoundcitrustrees. HouseholdSprays. Severalhomeownershave madethemistakeofsprayingcitrustreesandother plantswithspraysformulatedspecificallyforuse insidehomestocontrolhouseholdpests.These sprays,ingeneral,havetheinsecticidedissolvedin sometypeofpetroleumsolventsuchasrefined (deodorized)keroseneandshouldnotbeappliedto plantsbecauseinjurytotheplantsusuallyresults.Table1. DooryardCitrusPestControlChart. Pest Material1 OtherPestsControlled Remarks Scale Ethion Rustmites Spidermites Controlscitrussnow scaleonly. Ethion+oil Rustmites Spidermites Aphids Controlsmostspecies ofscaleinsects. Malathion Mealybugs Whiteflies Grasshoppers& katydids Doesnotcontrolchaff scale. Oil Whiteflies Spidermites Greasyspot Loosenssootymold Doesnotcontrolsnow scale.Donotapplyif treesarewiltingorina nearwiltstate.Donot applywithin3weeksof sulfur.Oilappliedafter Octobermayincrease susceptibilityoftreesto colddamageandmay reducethecropthe followingyear.Oil appliedinthefallmay inhibitsolidsformation andretardfruit coloring. Rustmites Ethion Spidermites Citrussnowscale

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page6Table1. DooryardCitrusPestControlChart. Pest Material1 OtherPestsControlled Remarks Ethion+oil Mostspeciesofscale insects Spidermites Kelthane Spidermites Spidermites Ethion Rustmites Ethion+oil Rustmites Mostspeciesofscale insects Kelthane Rustmites Oil Scale(doesnotcontrol citrussnowscale) Whiteflies Greasyspot Loosenssootymold Seecommentsunder scalepests. Aphids Malathion Mealybugs Scale Whiteflies Grasshoppers& katydids Mealybugs Malathion Scale Aphids Whiteflies Grasshoppers& katydids Whiteflies Oil Scale Spidermites Greasyspot Loosenssootymold Malathion Scale Mealybugs Aphids Grasshoppers& katydids Malathion Scale Mealybugs Aphids Whiteflies Scab Copperfungicidespray Applybeforenew growthstartsinthe springandwhen2/3of petalshavefallen. Benlate

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ControlofInsects,MitesandDiseasesofFlorida'sDooryardCitrusTrees Page7Table1. DooryardCitrusPestControlChart. Pest Material1 OtherPestsControlled Remarks Melanose Copperfungicidespray Scab Applyspraythoroughly toyoungfruit,4weeks aftertheflowersshed. Greasyspot Copperfungicidespray July.Spraysofcopper mayblackenexisting corkyareasoftherinds, butthiswillnotaffect eatingquality. Benlate July. Oil July.Seecomments underscalepests. 1Readlabelthoroughly;followlabeldirectionsformixingandapplicationrates.