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21SPRING2015SPUDSMART.COMhostsoraphidsonwhichlargepopulationscandevelop.-Top-killseedeldsearlytopreventlate-seasonvirusinection.-Avoidplantingsusceptiblevarietiesincloseproximitytoeldswithvarietiesthathavepoorsymptomexpression.-Plantcropbarriers.Theseconsistoanon-PVYhostcroporexamplecerealsplantedaroundsmallearly-generationseedlotstoprovideabuerbetweentheseedlotandthein-fightoaphids.Aphidsusuallylandattheinteracebetweenallowgroundandgreencrop.FUSARIUMDRYROTFusariumdryrotisadiseasethataectstubersinstorageandseedpiecesaterplanting.Itotenbeginsromexternalwoundsandsubsequentlyresultsindryandcrumblytantodarkbrowndecay.Rottedtissueotenormsinternalcavitieslinedwithungalmyceliaandsporesowhitetoorangeoryellowish-tanincolour.Howtomanageusariumdryrot-Plantdisease-reeseedpotatoes.-Onlyharvesttubersatertop-killwhenvinesarecompletelydeadtoensureskinmaturity.-Careulhandlingatharvestandinstorageisrequiredinordertoavoidbruisingandwoundingbruisesandcutscanactasentrypointsortheungus.-Cleanandsanitizestoragebinsandhandlingequipment.-Newlyharvestedpotatoesshouldbeheldatbetween12to15Cand90to95percentrelativehumidityortherstonetotwoweeksinstoragetopromotewoundhealing.Followingthecuringperiodtemperaturesshouldbeloweredtotypicallevelsusedorlong-termstorage.Dryrotdoesnotspreadinstorageithetubersareproperlyhealed.-Warmtubersbeorecuttingandplanting12to15Coronetotwoweeks.-Knivesonthecuttershouldbesharptomakeasmoothcutthathealseasily.-Cutseedshouldgothroughthewoundhealingprocesspriortoplantingoraseedpiecetreatmentshouldbeappliedandtheseedpiecesplantedimmediately.-Plantseedinwarmmoistsoilstopromotepromptsproutgrowth.-Protecttheseedromwindandsunlightduringplantingbecausedehydrationweakenstheseedpiece.-Ipossibleavoidirrigationbeoreemergence.-Applicationsonitrogeninexcessosoiltestrecommendationshouldbeavoided.Toomuchnitrogendelaysmaturityotubersandresultsinexcessiveskinningandbruising.-Post-harvestungicidesmaybeappliedtotubersgoingintostorageistorageproblemsareanticipated.PINKROTMostotenseenatharvestpinkrotresultsindarkouterskinsininectedtubers.Diseasedtuberscanaecthealthytubersatharvestoratbinilling.Althoughinectedtubersmaintainanormalshapetheinternalleshhasarubberytextureandturnspinkater15to20minutesoexposuretoair.Inadditionduetobreakdownotissuesbythepathogenandsecondaryorganismspinkrotinstorageisotenaccompaniedbyadistinctiveammoniaodour.Howtomanagepinkrot-Plantcleandisease-reeseed.-Carryoutaregularthree-yearcroprotation.-Plantpotatoesinwell-drainedsoil.-Priortoharvestingchecklowareasintheeldandroguediseasedplantsandtubers.-Avoidharvestingduringwetconditionsandkillvinesatleasttwoweeksbeoreharvesting.Delayharvestuntilthepulptemperatureisbetween7and10C.-Tuberswithsigniicantpinkrotshouldbeharvestedandstoredseparatelyorimmediategradingandmarketing.-Gradeoutrottedtubersbeoreplacingtheminstorage.Instorageturnonventilationsystemsimmediatelytokeepairmovingthroughthepileinordertodryanyrottingtubers.Cooltubersasquicklyaspossible.Keepthehumiditylowtopreventsecondarybacterialinectionromdeveloping.Theungusisusuallyinactiveattemperaturesbelow4.4C.-Fungicidesappliedin-urrowatplantingorappliedtotheoliageduringearlytuberizationcanreducepinkrotlosses.SOFTROTSotrotisabacterialdiseasethatotencausessecondarybreakdownoalreadyinectedtubers.Inectedtissuesareextremelysotandotenappearastan-tobrown-colouredwater-soakedareasorgranulartissues.Althoughrotcausedbythesotrotbacteriumisrelativelyodour-reesecondaryorganismsusuallycauseaoulsmell.Undermoststorageconditionstubersinectedwithanystoragediseaseexceptsilverscurcanbesusceptibletosotrotcausingurtherbreakdownoaectedtissues.Inapotatopilesotrotspreadsdownwardpotentiallyleadingtothebreakdownotheentirepilewithinaewdays.Howtomanagesotrot-Plantdisease-reeseedpotatoes.-Avoidexcessivesoilmoisturebeoreharvesttoreducelenticelinection.-Harvesttubersonlywhenmatureandonlywhensoiltemperaturesarelessthan20C.-Minimizemechanicaldamagetotubersduringharvestingandhandling.-Protectharvestedtubersromsolarirradiationanddesiccation.-Cooltubersto10Corlowerassoonaspossibleaterharvestandstoreattemperaturesaslowaspossiblepreerably1.6to4.5C.-Providegoodventilationtokeeptuberscoolandtopreventaccumulationocarbondioxideandmoistureilms.-Donotwashtubersbeorestorageandwhenwashingthembeoremarketingdrythemassoonaspossibleandpackagetheminwell-aeratedcontainers.-Useonlycleanwatertowashpotatoes.Contaminatedholdingtanksusedorsoakingpotatoesalmostassuresotrotinection.Treatwashwaterwithchlorinetoreducetheamountosotrotinoculum.