Rootstock Selection

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Title:
Rootstock Selection
Physical Description:
Fact sheet
Creator:
Castle, W.S.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
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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: December 1992."
General Note:
"HS-151"

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the submitter.
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IR00004628:00001


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FactSheetHS-151 December1992RootstockSelection1 W.S.Castle2Choosingarootstockisanimportantdecision.It shouldbecarefullyconsideredbecausesuchdecisions arerelativelypermanentintheireffectand,thus,in theirlong-termsignificance.Thestepsinvolvedin choosingarootstockmaynotalwaysbeobvious,but therearefactorsthattraditionallyhavebeen important.Amongthesearetheexperiencesand opinionsoffriends,neighbors,nurserymen,andthe growerhimself.Theinformationcanbeconflicting andconfusing,makingthechoiceofarootstock unnecessarilydifficultandsometimeswhimsical.What followsisjustoneapproachthatmaybehelpfulin selectingthebestrootstockforyourconditions.GATHERTHEFACTSABOUTYOURSITEThereisnosubstituteforhavingavailableas muchfactualinformationaspossible.Information shouldbeobtainedregarding: Soil-Texture,depth,hardpan,pH,chemical characteristics,waterholdingcapacity,drainage, nutrientstatus,etc. Elevationandairdrainage-Thesefactorsare stronglyrelatedtothepotentialforcolddamage. Nematodes-Thepresenceoftheparasiticcitrus andburrowingnematodeshasthepotentialfor simplifyingarootstockdecisionbecauseofthe easewithwhichmanychoicescanbeeliminated. Evenifthisinformationisnotusedinthe decision-makingprocess,itisstilluseful. Historical-Ifanewsiteisbeingplanted,learn aboutthesuccessesandfailuresofyour neighbors.Ifanareaisbeingreplanted,consider thereasonforreplanting.Forexample,didrough lemonfailinacoldsiteorweretheyieldson CleopatralowonaRidgesite?Thistypeof informationisinvaluable.KNOWYOUROBJECTIVEManydecisionsaremadewithintheframeworkof awell-definedgoal.Therefore,itisimportantto consider: Scioncultivar-Likechoosingarootstock,the cultivarselectedrepresentsachoicenotoftenor easilychangedafterplanting. Market-Juicequalitymaybelessimportantthan yieldifthefruitisforprocessing,andthiswould affectthechoiceofrootstock.Ifthefruitisfor thefreshmarket,theinfluenceoftherootstock onexternalqualitymaybecomemoreimportant. Time-Ifyouhaveashort-rangegoal,atreeon avigorous,productiverootstockmightbe appropriate.Forlongerrangeobjectives,another rootstockwithdifferentcharacteristicsmaybe moresuitable. 1.ThisdocumentisFactSheetHS-151,aseriesoftheHorticulturalSciencesDepartment,FloridaCooperativeExtensionService,Institute ofFoodandAgriculturalSciences,UniversityofFlorida.Publicationdate:December1992. 2.W.S.Castle,ProfessorandHorticulturist,CitrusResearchandEducationCenter,LakeAlfred,Florida,CooperativeExtensionService, InstituteofFoodandAgriculturalSciences,UniversityofFlorida,GainesvilleFL32611. TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,Dean

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RootstockSelection Page2KNOWTHEROOTSTOCKSTherearetworeadilyavailablesourcesof informationonrootstocks.Eachprovidesadifferent perspective.Theyare: Experience-Fewgrowershavehesitatedtoplant treesonrootstockssuchassourorangeorCarrizo citrangebecausethesestocksandtheir characteristicsarewellknown.Theboundariesof theirperformancehavebeenestablishedfrom yearsofcommercialuse.Practicalexperiencehas alsoshownthattheyhavetheirlimitations; nevertheless,theserootstocksaregenerallymore acceptablethanothersthatareuntried. Confidence(andlessrisk)isderivedfrom knowledge. Fieldexperimentsandresearchdata-Amajor functionofrootstockresearchistodeterminethe commercialpotentialofnewrootstocksandalso toensurethatthecapabilitiesofcurrentlyused rootstocksarecompletelyandclearlyunderstood. Thevariousfieldexperimentsestablishedforthis purpose,includingthoseincommercialgroves, representessentiallytheonlysourceofdata regardingnewrootstocks.Asaresult,theyare likelytoprovideanswersfortoday'simportant issues,suchastheincidenceofblightamongtrees onCarrizocitrangeandtristezadeclineamong treesonsourorange.Itwasn'ttoomanyyears agothatVolkamerlemonandSwinglecitrumelo rootstockswereunknowninFlorida.Now,oneof these,Swingle,isofconsiderablecommercial interest.RESEARCHPUBLICATIONSResearchdataarewidelydistributedthroughout avarietyofscientificjournals,trademagazines,and otherperiodicals.Thesedataareavaluablesourceof informationbutoftenremainasbitsandpiecesinthe literature.Therefore,afewhelpfulsummary-type publicationsarelistedbelow. Castle,W.S.,D.P.H.Tucker,A.H.KrezdornandC.O. Youtsey.1989. RootstocksforFloridaCitrus UniversityofFloridaCooperativeExtension PublicationSP42.(AvailablefromUniversityof Floridafor$6.36). Ferguson,L.,N.SakovichandM.Roose.1990. CaliforniaCitrusRootstocks .Universityof CaliforniaPublication21477. Krezdorn,A.H. SelectingCitrusRootstockforFruit SizeandQuality.Fla.GrowerandRancher, Vol.72(4),1979. Krezdorn,A.H. Rootstocks:HowTheyAffectYield Fla.RancherandGrower,Vol.72(5),1979. Krezdorn,A.H. CitrusRootstocks.Toleranceof EnvironmentalandDiseaseProblems .Fla.Grower andRancher,Vol.72(6),1979. Krezdorn,A.H. Rootstocks:TheirRelationtoVirus DiseaseandBlight.Fla.GrowerandRancher, Vol.72(7),1979.CHOOSINGTHEROOTSTOCKThefirstthreestepsaretherelativelysimple informationgatheringprocess,whichprovidesasound foundationforthefinalstep-selectingarootstock. Thereareseveralfactorsthatcombinetomake thefinalstepmoredifficultthantheprecedingones. Theseincludethelackofcompleteinformationabout anyrootstockaswellasrecognizingthatnorootstock isperfect.Unfortunately,allthedesirableattributes foracitrusrootstockhaveneverbeencombinedin onerootstock.Everyrootstockhascertainweaknesses aswellasadvantages.Perhapsmoreimportantly, though,isthatallrootstocksdonothavethesame disadvantagesorstrengths. Anotherconsiderationaffectingthechoiceofa rootstockistherelativeimportancegivento individualrootstockeffects.Toillustratethispoint andthosementionedabove,consider,forexample, treeson Citrusmacrophylla .Theyareprecocious,bear well,andarehighlyresistanttofootrot;however, theyarealsoveryeasilycolddamagedandthefruit haveapoorqualityjuice.Whichofthesetraitsisof greatestconcernunderyourgrovesiteconditionsand withyourobjectives? InFlorida,thechoiceofarootstockisgenerally basedonacombinationofconcernforproductivity andtreesurvival.Thefundamentalquestionwithfruit producedforprocessingishowtoproducethe maximumquantityofsolublesolidswiththeminimum numberofrisks.Therefore,priorityisnormallygiven torootstockeffectsonyield,butsometimesother factorsbecomelimiting.ExamplesinFloridaarethe potentialforcolddamageandsusceptibilitytofootrot orrootrot,tristezaandblight.Atothertimes,asingle rootstockcharacteristicbecomeslimiting,suchas

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RootstockSelection Page3tristezasusceptibilityinsourorange.Incontrast,some rootstockcharacteristicsareessentiallynon-limitingor canbecontrolledandare,therefore,lessimportant. Iftreesonacoldtolerant,productiverootstockare susceptibletodrought,theycanbeirrigated. Thefinalstepinselectingarootstockessentially involvesdevelopingacompositeassessmentofa rootstockbasedonitsindividualcharacteristicsand thenchoosingtherootstockthatbestmatchesyour interestsandgoals.Asnoonerootstockislikelytobe entirelysatisfactoryinanysetofcircumstances,itis oftenwisetoconsiderusingtwoorthree.Iftwoor moreareselected,settingagrovesothattreesare plantedonalternatingrootstocksisnot recommended.Rootstocksshouldbeselectedto matchspecific,localconditionsespeciallywhen plantingthehighlyvariablesoilsfoundinthe flatwoods. Soilanddrainagearecriticalfactorsand areoftenthebasisforrootstockdecisions. Itistheauthor'sopinionthatsoilandyieldare prioritydeterminants.Differencesinjuicequality usuallydonotexceedthelargerdifferencesinyield amongrootstocks. Specificrootstockcharacteristicsaredescribedin anothersection.Long-termfieldtrialdatawith financialanalysisareavailablefromtheauthor.