Citrus Reset Management

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Title:
Citrus Reset Management
Physical Description:
Fact Sheet
Creator:
Jackson, Larry K.
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.
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Published
General Note:
"Publication date: June 1992. Revised: June 1994."
General Note:
"HS-142"

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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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IR00003741:00001


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FactSheetHS-142 June1994CitrusResetManagement1 L.K.Jackson2Replacementofdeadanddiseasedtreesin Floridacitrusgroveshasalwaysbeenanimportant partofthetotalproductionprogram.Today,tree replacementismoreimportantthaneversince overheadandproductioncostsareescalatinganda fullstandofproductivetreesisessentialtomaximize productionandprofits.Diseasesandfreezeshave beenparticularlytroublesometoFloridacitrus growersforthelastdecade.Extensivetreelosses coupledwiththeeconomicnecessityofregular resettinghavecausedmanygrowerstoinvestigate waystoachievenewefficienciesinresetmanagement. Caringforyoungcitrustreesisalways troublesomebecausetheyrequirefarmoreattention thanlarger,establishedtrees.Florida'ssandysoils, highsummertemperatures,possiblelowwinter temperatures,andscatteredrainfallpatterns complicateyoungtreecarebyforcinggrowersto water,protect,fertilize,andweedyoungtrees regularlyorfaceextensivelosses.Resetsoften presentanevengreaterproblembecausetreesare usuallyscatteredthroughoutablockoflargertrees, wheretheycompetewithlarge,full-growntreesfor limitedsuppliesofmoisture,nutrients,and sometimes,sunlight.Scatteredresetsfrequentlyhave seriousweedproblemssinceremovaloftheprevious treeallowstheareatoreceivemoresunlightand providesmorefavorableconditionsforweedgrowth. Sinceresetsareusuallyscatteredthroughoutablock ofmuchlargertrees,theyareoftendifficulttolocate andmaybeaccidentallyoverlooked,resultingin inadequatecare. Researchersandgrowersarecontinually developingnewmethodsofdealingwithresetcare. Thetextthatfollowsdiscussesawiderangeoflabor andenergy-savingtechniquesforprovidingyoungtree care.ManyoftheseshouldproveusefultoFlorida citrusgrowersconfrontedwiththeproblemof managingresets.PLANNINGTHERESETPROGRAMEfficientgrovemanagersincludetreeremovaland resettingasaroutinepartoftheproductionprogram andoftenassignspecialtimesorspecialcrewstodeal specificallywiththistask.Certaintimeperiodsinthe managementschemeforthebearinggroveshouldbe designatedforthisjob,justastherearefor fertilization,irrigation,insectanddiseasecontrol,and pruning. Planningaheadisveryimportantbecausethereis oftenalagbetweenthetimereplacementtreesare orderedandwhentheyarereceived.Thewaitforthe desiredrootstockandscioncombinationmaybeas greatas1to2years,soreplacementtreeneeds shouldbeanticipated(whenpossible)andorders placedsotheycanbeobtainedwhenneeded. 1.ThisdocumentisFactSheetHS-142,aseriesoftheHorticulturalSciencesDepartment,FloridaCooperativeExtensionService,Institute ofFoodandAgriculturalSciences,UniversityofFlorida.Publicationdate:June1992.Revised:June1994. 2.LarryK.Jackson,professor,extensionhorticulturist,DepartmentofFruitCrops,CitrusResearchandEducationCenter,LakeAlfred, 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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CitrusResetManagement Page2Recordsfrompreviousyearsshouldbehelpfulin estimatingthetreesrequiredinanannualresetting program.Figuresderivedfromsuchrecordsare averages,however,anddonottakeintoconsideration unanticipatednaturaldisasterssuchasfreezesor hurricaneswhichmightincreasethenumberof replacementtreesneeded. Anannuallyupdatedgroveplatisprobablythe bestmethodforassessinggeneralgroveconditionand productivity.Thiscanhelpdeterminethenumberof treeswhichwillbeneededandwheretheyshouldbe placed.Resetplatscanthenbepreparedtolater helpequipmentoperatorslocatenewly-plantedtrees forperiodiccare.Platscanbepreparedbyhandor withtheassistanceofacomputer.Localcounty extensionofficescansupplyinformationaboutthe computermappingprogramwhichisavailable throughIFAS.PLANTINGSITEPREPARATIONTheresetplantingsiteshouldbewell-prepared. Thesoilshouldbethoroughlyaerated,andweedsand rootsremovedbeforeplanting.Arotovatorhasbeen foundquiteeffectiveforthistasksinceitprovidessoil aerationandhelpsremoveroots.Attheveryleast,a non-residualherbicideshouldbeappliedtothereset areatogetweedsundercontrolbeforetheyoungtree isset.Theuseofmostresidualherbicidespriorto plantingisdiscouragedunlessextremelylowratesare usedsinceyoungtreesareparticularlysusceptibleto herbicideinjury.Labeldirectionsforsuchusesmust befollowedexplicitly. Pre-plantfumigationisusuallyquiteeffective becauseitwillliterallysterilizeavolumeofthesoil andgreatlyreduceoreliminaterootsprouts,weed, nematode,andfungusproblemsforatleastseveral weeks.Treesplantedinfumigatedsitesmaygrowoff morerapidlyandusuallyhavefewerdiseaseproblems thantheircounterpartsinunfumigatedsites.Thisis believedtobeduetooneormoreofthefollowing reasons:1)eliminationofweeds,nematodes,and pathogenicorganismsfromthesite;2)chemical pruningofrootsfromadjacenttreeswhichmight competewiththereset;and,3)killingofoldrootsleft fromthetreewhichpreviouslyoccupiedtheresetsite. Followfumigantinstructionscarefully.Improper applicationcouldresultininjurytotheapplicator. Also,failuretoobserverecommendedwaitingperiods afterfumigationcanresultininjuryordeathofthe replacementtree.BUYINGANDRECEIVINGTREESHighqualitytreesareessentialforresets.These plantswillbeplacedinanintenselycompetitive situationandmaysometimesreceivelessthanideal care,sothereisnoroomforcompromisingtree quality.Onlytheveryfinesttreesfromregistered sourcesshouldbepurchasedsincetheinitialcostis butafractionofthetotalcostofbringingsuchatree intoproduction. Theselectionofbare-rootorcontainer-grown replacementtreesislargelyamatterofgrowerchoice oravailability.Onecanfindproponentsofeither typeoftreebutfundamentally,therestillseemstobe apreferenceforbare-roottreeswhenavailable. Propersitepreparation,carefultreeplanting proceduresandqualityaftercareareessentialfor success. Plantingsitesshouldbepreparedwellinadvance ofreceiptofthetrees.Thisisparticularlyimportant forbare-roottrees,whichshouldbeplantedassoon aspossibleaftertheyarereceived.Ideally,trees shouldbeplantedonthesamedaytheyarereceived. Undernocircumstancesshouldbare-roottreesbe allowedtodryout.Tominimizerootdesiccationand damage,theyshouldbekeptcoolandmoistuntilthey areplanted.PLANTINGTHETREEInspectbare-roottreesforbrokenordamaged rootsandremovethembyclippingnearthedamaged area.Sincethefibrousrootsystemofbare-roottrees isusuallyseverelycutbackwhentheyaredug,itwill benecessarytoremovesomeoftheleavesand branchesinordertobalancethetopwiththeroot system.Mostoftenthisisdoneaboutthetimethe treesaredugbyremovingfromathirdtoahalfof thetopofthetree.Thisisbestaccomplishedby partiallycuttingbackindividualbranches,ratherthen removingentireones. Container-growntreesshouldberemovedfrom thecontainerandinspectedforevidenceofpotbinding--amassofrootsgrowinginaspiralaround therootball.Makeseveralverticalslashesaboutone inchdeepthroughtherootballtoencourageroot branching.Theseslashesalsoallowthepottingsoil

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CitrusResetManagement Page3androotstointerfacemorecloselywiththesoilinthe plantingsite.Itmaybeeasiertocutsomeofthe rootswithpruningshearsandpullthemsothey protrudefromtheball. Acommonproblemwithcontainer-grownplants isthatthepottingmixtureisoftenhighlyorganic. Suchmaterialsformareaswhicharedifficultto permeatewithwateraftertheyoungtreeisplantedin sandysoilsandirrigated.Theouterthirdormoreof theorganicballshouldberemovedbypullingor washingsothattherootscanextendintothesoilin whichthetreeisplanted.Otherwise,thetreemay notgrowoffsatisfactorily. Digtheplantingholelargeenoughto accommodatetherootsystem.Spreadtherootsout intheholeifnecessary.Settheplantslightlyhigher thanitgrewinthecontainer.Itisimportanttokeep thebudunionwellabovethesoilleveltohelpavoid footrot.Thisiseasytodobylayingalongboard, rake,orshoveloverthecenteroftheholewitheach endextendingoverundisturbedsoil.Thisshows exactlywherethesoillineshouldbe.Sincethesoil (andtree)arelikelytosettleslightly,setthesoilline oftheyoungtreeaboutoneinchhigherthanthe bottomoftheboardorhandle. Backfillaroundtheplanttohalffilltheholeand pressthesoildowntoremoveairpockets.Water thoroughlyandallowtosettle.Backfilltonearthe topofthehole;firmthesoildownandwateragain. Finishfillingthehole,firmthesoilaroundthetree andformawaterbasinarounditunlessalowvolume irrigationsystemisinplacewhichcansupplywateras needed. Thewaterbasinisformedasaridgeorringof soil,4to6incheshigh,6to8incheswideatthebase andabout3feetindiameter.Whenthebasinis completedandtampedfirmly,fillwithwater.Sucha basinshouldhold7to10gallonsofwater,whichis enoughtosupplytheyoungtree'sneedsuntilthenext wateringisdue.Thewaterbasinshouldremainfor 6monthstoayear.Whileawaterbasinisconsidered anantiquatedtechnique,itcouldbeusefulfor supplementalwateringsifthesystemisnotusedwith thefrequencyrequiredbythenewly-plantedtrees. Growersmaywanttoconsiderincreasingtree densityinareaswhichneedtoberesetextensively. Coldpockets,poorlydrainedareas,weaksoils,or groveswithdiseaseproblemscouldbeplantedata reducedspacingtoincreaseearlyyields.Inmany cases,suchlocationsmightbebetterifabandoned completely.Decisionstoreplantorabandonproblem sitesshouldbemadeonlyafteracarefuleconomic analysisoftheparticularsituation.WEEDCONTROLWeedscompetewithyoungcitrustreesfor moistureandnutrientsandtheymustbecontrolled forpropertreegrowth.Weedcontrolaroundareset siteshouldbeconsideredat3periods:1)pre-plant,2) earlypost-plantand,3)afterthetreeisestablished. Controlofweedspriortoplantingcouldbe providedinseveralways.Pre-plantfumigationwill usuallyprovideweedcontrolforseveralweeksafter plantingunlesstheoperationisundertakentoofarin advanceofplanting.Ifresidualherbicidesareused, theyshouldbeusedingreatlyreducedratesandwell inadvanceofplantingsothatharmfulresiduesdonot remainwhichmightdamagethereset.Contactor growthregulatingherbicidesareusuallypreferred sincetheydonotleavesoilresidues. Weedcontrolduringtheestablishmentperiodor approximatelythefirstyearisfrequentlyquite difficult.Handlaborisscarceandexpensive.Trunk damagebyhoesorothercultivationequipment furthercompoundstheproblem.Chemicalweed controlprovidesatleastapartialsolutiontothe problemduringthisestablishmentperiod.Inthe past,theuseofresidualchemicalswasnot recommendedduringthefirstyearinthegrove. However,thereisnowafairlywideselectionof herbicidesavailablewhichcanbeusedonyoung trees.Mostofthecompoundswillrequirereduced ratesofmaterialswithgreaterfrequenciesof application.Besuretoreadlabelscarefullyfor restrictionsontheuseofherbicidalmaterials. Aftertheresethasbeenplantedforayearor more,modificationsoftheweedcontrolprogramcan beconsidered.Labelsofmaterialsunder considerationshouldbecheckedcarefullyforhazards orrestrictionspriortouse.Reducedratesofresidual herbicidesforyoungtreesarerequiredtoassurethat noharmwillcometoresetsplantedamongolder trees.Speciallymodifiedherbicideapplicatorsare availablewhichenabletheequipmentoperatorto deliverahalf-rateofmaterialathisdiscretion.

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CitrusResetManagement Page4FERTILIZATIONFrequentresetfertilizationrequiresextraeffort beyondtheneedsofthebearinggrove.Water-soluble fertilizersthatcanbeappliedwithirrigationwaterare beingusedbysomegrowers.Thesematerialsare injectedintoirrigationsystemsandisalsooftenused wheretreesareirrigatedwithawaterwagonrig. Greatcaremustbetakentoensurethatproperrates offertilizermaterialsaredispensedtoprevent nutritionaldeficienciesortoxicexcesses.Frequent lightapplicationsusuallyproducebestresultsand lessenthedangerofleachingbutthesepracticesneed tobeevaluatedforcosteffectiveness.Highlyorganic orslow-releasefertilizersthatreleasenutrientsslowly mayreduceapplicationfrequency.Thetotalamount ofnutrientsappliedonanannualbasisshouldremain thesame.Savingsresultbecausefewertripstothe resetareneededeachyeartoprovidefertilizer.IRRIGATIONYoungcitrustreesrequirefrequentbutmoderate waterapplicationforsurvivalandpropergrowth. Competitionforwaterisaccentuatediftheyoungtree isclosetooldertrees(asmostresetsare)orifweeds areallowedtogrowintherootingzoneoftheplant. Anythingthatcanbedonetodiscouragecompetition foravailablesoilmoistureshouldbebeneficialtothe youngtree. Whereirrigationsystemsareinplace,special modificationscansometimesbemadetosupplywater forresets.However,theirrigationfrequency necessarytosustainamaturegroveisrarelyadequate forgoodgrowthofnewly-settreesandyoungtrees shouldbecheckedfrequentlytobecertaintheyare receivingsufficientwater.SPROUTINGANDCOLDPROTECTIONYoungcitrustreesrequireperiodicsprout removal.Thegrowthregulatornaphthalenaceticacid (NAA)ina1%solutionhasshownpromiseasa sproutinhibitorandcanbesprayeddirectlyontree trunks.Thismaterialshould not beappliedinthefall totreeswhichmaybedamagedbycoldsincesuch treeswouldbeunabletore-sproutandgrowanew topiffrozenback. Theuseofinsulatingtreewrapsusuallyeliminates theneedforsproutingandaffordssome degreeofcoldprotection.Mostwrapsaffordonly limitedprotectionandcannotsupplythesamedegree ofprotectionaswell-constructedsoilbanks.The combinationofmicrosprinklerirrigationandtree wrapshasbeenshowntoprovideexcellentcold protectionforlowerportionsofyoungcitrustrees. Additionalinformationoncoldprotectionbywraps, irrigationorcombinationsofmethodsisavailable fromlocalextensionoffices. Wrapsoftenstayinplaceforupto3yearsand mayneednotberemoveduntilthetreeiswell established.Theyshould,however,bechecked periodicallyforthepresenceofantsorfungus diseases.Eventhoughtheprotectivevalueofawrap isnotasgreatassoil,theeaseofapplication, permanence(comparedtobanks)andfreedomfrom sproutsmaybeenoughtojustifytheiruse.Wraps willalsoprovideprotectionfromerrantherbicide applications.Soilbankswillprovidemoreprotection butaredifficulttoconstructandmaintain.They mustberemovedinthespringandreconstructedthe nextwinter,andmayalsopredisposetheyoungtree toinjuryfromcertaininsectsanddiseases. Therearenosimpleanswerstothereplant problem.Eachsituationisdifferentandrequires carefulhorticulturalandeconomicconsiderationto arriveatthebestprocedure.REMOTESENSINGSinceresetsareusuallyscatteredthroughouta blockofmuchlargertrees,theyareoftendifficultto locateandmaybeaccidentallyoverlooked,resulting ininadequatecare. Anannuallyupdatedgroveplatisprobablythe bestmethodforassessinggeneralgroveconditionand productivity.Thiscanhelpdeterminethenumberof treeswhichwillbeneededandwheretheyshouldbe placed.Resetplatscanbepreparedtolaterhelp equipmentoperatorslocatenewly-plantedtreesfor periodiccare. Themosteconomicalmethodofupdatingagrove plat,andonewhichprovidesvaluableinformationin additiontoresetlocation,isremotesensing.