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BIOLOGICALCONTROLOFCOGONGRASS.Imperatacylindrica(L.) Beauv. CAMILLAB.YANDOC ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL OFTHEUNIVERSITYOFFLORIDAINPARTL\LFULFILLMENTOF THEREQUIREMENTSFORTHEDEGREEOFDOCTOROF PHILOSOPHY UNIVERSITYOFFLORIDA . ^ 2001 . Copyright2001 by CamillaB.Yandoc Tomyparents,FranciscoandMariettaYandoc ACKNOWLEDGMENTS Iwouldliketothankmymajorprofessor,Dr.RaghavanCharudattan,for believinginmeandforgivingmetheopportunitytoenrichmyselfbothprofessionally andpersonally. IalsowouldliketothankDr.FrancisW.Zettlerandmycommittee members,Dr.RichardD.Berger,Dr.JamesW.Kimbrough,andDr.DonnG.Shilling, forthetime,interestandsupporttheyhavegivenme.ManythanksgotoJimDeValerio, KarenHarris,JayGideon,HenryRoss,JasonMcCombs,MattPusateri,JoshRhames, MarkElliott,EldonPhihnanandHermanBrownforallthehelptheyprovidedduringthe courseofmyexperimentsandfortheirfriendship.Thanksgotomyformerlabmates.Dr. ErinRosskopf,Dr.JugahKadir,Dr.S.Chandramohan,Dr.DauriTessman,Dr.Gabriela Wyss,andMs.AngelaVincent. ThanksgotoallmyfriendsinthePlantPathology Department,Mr.LuciousMitchell,Mr.GeneCrawford,theUSPS,thegraduatestudents, Ms.LaurettaRhames,Ms.DonnaBelcher,KendraDavis,andMs.GailHarris,and everyoneelsewhohelpedmeinonewayoranother. ManythanksgotoDr.Ziyad MahfoudandMs.UpasanaSantraforhelpingmewiththedataanalysis. Iwouldliketothankmyfamily,myMomandDad,mysisters.Carmenand Guadalupe,brotherDeodato,mynephewsZygieandMickey,andmynieceMirandafor alltheloveandsupport.ThanksgotomynieceIsabella,forremindingmetoalways countmyblessings. ThanksgotoGino,forhislove,friendshipandpatience.Thanksgo toAntonioandSheilaGomezandfamily.BobandPamKemerait,Dr.andMrs.Abies . iv and,andtoallmyfriendsbackhomeandallmyfriendsinGainesville.Finally,Ithank Godforalwaysmakingthingsworkoutfine. V TABLEOFCONTENTS ACKNOWLEDGMENTS iv ABSTRACT ix CHAPTERS U- 1 INTRODUCTION .1.: 1 CogongrassIntroductionintotheUnited States 7 EconomicandEcologicalImportanceof Cogongrass 8 MorphologyandBiology 12 Habitat 14 CogongrassManagement 15 2 EVALUATIONOFFUNGALPATHOGENSASBIOLOGICAL CONTROLAGENTSFORCOGONGRASS 23 - Introduction 23 MaterialsandMethods 25 Results 30 Discussion 37 3 MASSPRODUCTIONOFINOCULUMOFBipolarissacchari ANDZ)recA5/erag/^an/eaANDDETERMINATIONOF " OPTIMUMCONDITIONSTOMAINTAINSPORE " ' . VL\BILITYDURINGSTORAGE 44 i ^ Introduction 44 MaterialsandMethods 49 vi , Results 54 Discussion 65 4 THEEFFECTOFOILFORMULATIONONTHE BIOHERBICIDALEFFICACYOFBipolarissacchari ANDDrechsleragigantea 70 Introduction 70 MaterialsandMethods 73 Results 79 Discussion 93 5 EVALUATIONOFHOSTRANGEOFBipolarissacchari ANDDrechsleragigantea 97 Introduction 97 MaterialsandMethods 100 Results 102 Discussion 103 6 FIELDEFFICACYOFBipolarissacchariandDrechsleragigantea ASBIOHERBICIDESOFCOGONGRASS Ill Introduction Ill MaterialsandMethods 116 Results 120 Discussion 136 7 SUPPRESSIONOFCOGONGRASSWITHBIOHERBICIDE APPLICATIONANDPLANTCOMPETITION 142 Introduction 142 MaterialsandMethods 144 Results 148 Discussion 158 vii .1 8 SUMMARYANDCONLUSIONS 162 REFERENCES. .168 BIOGRAPHICALSKETCH 194 : \ AbstractofDissertationPresentedtotheGraduateSchool oftheUniversityofFloridainPartialFulfillmentofthe RequirementsfortheDegreeofDoctorofPhilosophy BIOLOGICALCONTROLOFCOGONGRASS . . .w CamillaB.Yandoc December,2001 Chairman:RaghavanCharudattan MajorDepartment:PlantPathology Twofungalpathogens,BipolarissacchariandDrechsleragigantea,were evaluatedfortheirpotentialasbiologicalcontrolagentsforcogongrass(Imperata cylindrica[L.]Beauv.). Applicationofsporesuspensionsofeachofthesefungithat containedlO'*-10^spores/mland1%gelatinresultedin30-50%diseaseseverity,ona ratingscalewith50%asthemaximumdiseaseseverity. Diseasesymptomsrangedfrom foliarlesionstoblighting. Sporesformulatedinanoilemulsioncausedmoredisease severityinthegreenhousetrials. Massproductionofsporeswasachievedinthe laboratorywithsohdsubstrateculturingtechniques. Sporesdriedat30-40''Cfor5days andstoredatlowtemperature(10-25°C)andlowhumidity(30-60%)RH)remainedviable foratleast10weeks. Inhost-rangetests,19plantspeciesinsixfamilies(Alliaceae, Apiaceae,Asteraceae,Cucurbitaceae,Poaceae,andSolanaceae)werefoundtobe ix susceptibletoB.sacchariformulatedinoilemulsion. Susceptibilityofthespecies outsidethefamilyPoaceaewasattributedtothepredispositionofthetestplantsbytheoil formulationandtheirageandvigor. ^ ' Amongtheresistantgrassspecieswasbahiagrass,acommonlyusedturfand pasturegrassspeciesinFlorida. Inexperimentsinthegreenhouse,B.sacchari | selectivelycontrolledcogongrassandreduceditsabilitytocompetewithbahiagrassin cogongrass-bahiagrassmixtures. Thus,B.saccharicanbeusedtosuppresscogongrass andtoallowtheestablishmentofamoredesirablespecies,suchasbahiagrass. Infieldtrials,therewasasignificantinteractionofthesporeconcentration,oil concentrationofthecarrier,andapplicationvolumeontheefficacyofB.sacchariandD. gigantea. Generally,applicationofalargervolumeofinoculum(800ml/m^)that contained10^or10^spores/mland18or26%oil,appliedwithahand-pumpedsprayer, resultedinthehighestlevelsoffoliarblighting(>70%onaratingscaleof0-100%) duringthe6-weekexperimentalperiod. Applicationof5.sacchariandD.gigantea, singlyorasamixtureattherateof200ml/m with10 spores/mlwithanultra-low- volume-applicatorresultedin>70%diseaseseverityinthefield. Bipolarissacchariand D.giganteahadtheefficacytobebiologicalcontrolagentsofcogongrass.