PlantingDate,Yield,andNitrogenManagementforStrawberriesintheCoastal

PlainofVirginia

By

UrsulaTankardDeitch

MajorProject/ReportsubmittedtothefacultyofVirginiaPolytechnicInstituteandStateUniversityin

partialfulfillmentoftherequirementsforthedegreeofOnlineMasterofAgriculturalandLifeSciences

InEnvironmentalSciences

MarkReiter,ChairSteveRideoutZacharyEaston

GregoryWelbaum

April18,2016EasternShoreAgriculturalResearchandExtensionCenter

Painter,VA

ii

PlantingDate,Yield,andNitrogenManagementforStrawberriesinthe

CoastalPlainofVirginia

Abstract

Freshmarketstrawberry(Fragaria×ananassa)availabilityinmidtolate-Aprilsignalsthe

beginningoflocallyavailablefreshfruitandvegetablesforthemid-Atlanticregion.Ofthe290

acresoffreshmarketstrawberriesgrowninVirginiaannually,themajorityareproducedinthe

coastalplainofVirginiausingintenselymanagedannualhillproductionsystems.Theobjective

ofthisstudywastoevaluatethepotentialyieldofstrawberries,determinehowyield

componentschangewithplantingdateandcultivar,andassessthefertilitymanagement

techniquesrecommendedbyVirginiaCooperativeExtension’sCommercialVegetable

ProductionGuideforstrawberries.June-bearingcultivars‘Camarosa’and‘Chandler’were

growninPainter,Virginiaduringthe2012-2013season.Threeplantingdates(Sept.21,28,and

Oct.5)wereassessedwhileevaluatingthecultivarsperformance.Petiolenitrate-Nreadings

andleaftissuewerecollectedatinitialflowerandmid-flowertoevaluatetheaccepted

fertigationrecommendations.Thecultivartrialyieldedbetween7,205–21,393lbs./acre.

Overall,‘Camarosa’yieldedhighestwiththeearlyplantingdate(Sept.21;21,393lbs./acre).As

theplantingdatesmovedlaterintothefall,‘Camarosa’lostyieldwhiletheyieldfor‘Chandler’

remainedconstantandaveraged9,705lbs./acre.Harvestpickdataalsoindicatedthat

‘Camarosa’outperforms‘Chandler’bothearlyandlateintheseasonforberrynumberand

yield.Petiolenitrate-NandleaftissuedatasuggestedthatexcessNfertilizationleadstolower

yields.Inconclusion,strawberrycultivar‘Camarosa’shouldbeastandardforfarmer’sinthe

iii

mid-Atlanticandplantedlatetomid-SeptemberwhilecontinuouslymonitoringandadjustingN

fertilityasneeded.

iv

TableofContents

Abstract..........................................................................................................................................ii

TableofContents..........................................................................................................................iv

ListofTables..................................................................................................................................v

ListofFigures.................................................................................................................................vi

Introduction...................................................................................................................................1

MaterialsandMethods.................................................................................................................5

ResultsandDiscussion..................................................................................................................6

Conclusions.....................................................................................................................................11

References......................................................................................................................................23

v

ListofTablesTable1.Plantyieldforaplantingdate(PD)×cultivarinteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic.................................................................12Table2.Totalnumberofstrawberriesharvestedperharvestdateforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic.................................................................13Table3.Yieldofstrawberriesperharvestdateforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic............................................................................................14Table4.Averageweightofstrawberriesperharvestforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic..................................................................................15Table5.Weightperberryforaplantingdate(PD)×cultivarinteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic............................................15Table6.Leaftissuenutrientconcentrationsatmid-flowerforsandyloamsoilsinthemid-Atlantic..............................................................................................................................16Table7.Petiolenitratereading#2–Aplantingdate(PD)×cultivarinteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic............................................16

vi

ListofFigures

Figure1.Mid-AtlanticcoastalplainoftheUnitedStatescomprisedmainlyofsandyloamsoilsinthetemperatezone......................................................................................................................17

Figure2.Annualhillproductionsystemofstrawberriesonsandyloamsoils.............................18

Figure3.Petiolenitratelevelscollectedatinitialfloweron2May2013andatmid-floweron9May2013inPainter,VAinrelationtostrawberryyieldoverallthreeplantingdates................19

Figure4.Leaf%Ncollectedatinitialfloweron2May2013inPainter,VAasitrelatestostrawberryyield............................................................................................................................20

Figure5.Leaf%Scollectedatinitialfloweron2May2013inPainter,VAasitrelatestostrawberryyield............................................................................................................................21

Figure6.Petiolenitratelevelsatinitialfloweron2May2013inPainter,VAinrelationtoleaf%Nconcentrationsfromthesamedate.........................................................................................22

1

Introduction

InVirginiaapproximately290acresoffreshmarketstrawberries(Fragaria×ananassa)

aregrownannually(USDept.Agriculture,2012).Thisequatestonearly$4.466milliondollars

infarmgatevalueeachyearfromstrawberrysalesinVirginia(USDept.Agriculture,2012).The

majorityofstrawberryproductionoccursinthecoastalplainofVirginia(Fig.1)andislocally

marketed.Salesbypick-your-own,pre-pick,roadsidestands,andfarmermarkets’occurovera

5-weekperiodandkickoffthesummersmallfruitandvegetableseason.Thepeakharvest

monthsinVirginiaarelateApril,May,andearlyJune.

SoilsinthecoastalplainofVirginiaarepredominatelysandyloams(~65%sand,25%silt,

and10%clayinthe0-6-inchhorizon)(USDA-NRCS,2016),andcoarsertexturedsoilshavea

greaterpropensitytoleachnutrientslikenitrogen(N)andsulfur(S)comparedtofinertextured

soilswithgreaterconcentrationsofsiltandclay(Zotarellietal.,2007).Itwasalso

demonstratedthatphosphorus(P)mayleachinsandyloamsystemsafteraPsaturationpointis

reached(Han,2015).Asaresult,sandyloamsoilshaveimportantenvironmentalandcrop

productionimplicationsforfreshwaterandsaltwatersystems;whichisespeciallyimportant

duetosmallfruitproductionbeinglocatedintheChesapeakeBayWatershed.

IntheeasternUnitedStates,strawberriestraditionallyweregrowninthematted-row

productionsystemwherestrawberryplugsaresetinthespring,andcrownsdevelop

throughoutthesummergivingrisetorunnerplantsthatfillinthebeds.Fruitisfirstharvested

inthespringofthesecondyearandplantsaretypicallyleftinthegroundforseveralseasons

(Fernandez,2001).Matted-rowsystemscontinuetobeofsignificanceinareasremovedfrom

theseaboardandathigherelevations(Hokanson,2000).However,theannualhillproduction

2

system(Fig.2),whichwasdevelopedinCalifornia,isthemostcommonlyusedsystemby

strawberrygrowersinthecoastalplainofthemid-Atlantic.Thehillsystemisalsoreferredtoas

“strawberryplasticulture”inwhichstrawberrytransplants(fresh-dugorplugs)areplantedin

earlyfallindoublerowsonfumigatedraisedbedsthatarecoveredwithblackplasticmulchat

plantdensitiesof≈17,400plants/acre(Poling,1993).Thefallplantedtransplantsarethen

harvestedthefollowingspringandaremostcommonlyfruitedonlyoneyear(Hokanson,2000).

Doubledriptubingistypicallyburied1to2inchesdeepundertheplasticmulch.Theannual

hillsystemprovidesadegreeofweedandpestcontrolthroughthecombinationofplastic

mulchandsoilfumigation.Otherimportantadvantagestotheannualhillproductionsystem

overthepreviouslyusedmattedrowculture,includeearlierandlongerharvests,cleanerfruit,

thepotentialtocontrolwaterpenetration,abilitytofertigatethroughthedripirrigation

system,andincreasedqualityandyields(PattisonandWolf,2007;Poling,2004).

Commercialstrawberryproductionrequiresintensiveandprecisefertilization.Fertilizer

applicationsthroughdripirrigation(fertigation),undertheannualhillproductionsystem,

allowsfortheprecisetiminganduniformdistributionoffertilizernutrients.Fertigationcan

reducefertilizerusagesandminimizegroundwaterpollutionbyapplyingfertilizerwhereand

whentheplantneedsthenutrient.About50%oftheN(60-75lbs.N/acre),50%oftheK,andall

oftherecommendedPisappliedpre-plantinthefallpriortolayingplasticmulch,withthe

remainingNandKbeingappliedinthespringina1:1ratiothroughthedripirrigationsystem

(Poling,1993).Thesepre-plantfertilizerapplicationsofNandKsupplyearlynutritiontothe

plantinthefallandearlywinterwhenmid-Atlanticgrowerstypicallydonotruntheirdrip

irrigationsystems(Poling,1993).Inthespring,dripirrigationapplicationsbeginatgreen-up

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andcontinuethroughharvest.ThecurrentNrecommendationforstrawberriesinanannual

hillproductionsysteminFloridaisfordailyinjectionsbetween0.30and0.76lbs.Nperacreper

day,dependingonthephenologicalstageofthecrop,withamaximumof152lbs.Nperacre

duringtheseason(HochmuthandAlbregts,1994;Hochmuthetal.,1996).Strawberriesgrown

inthemid-AtlanticregionfollowasimilarNfertilizationregimenwithamaximumof120lbs.N

peracrerecommendedforsandyloamsoilsinanannualhillsystem(Wilson,etal.2012),with

60lbs.ofNappliedinthefallatbedformationandtheremainderappliedthroughdripinthe

spring.

Collectingpetiolesamples,startingatgreenup,andanalyzingnitrate-Nconcentrations

isthemostaccuratemethodologyfordeterminingfertilizeramountsthroughoutthegrowing

season.Apetiolenitratemetercanbeusedtomonitorthenitrate-Nconcentrationsandthe

fertigationschedulecanbealteredbasedonnitratesufficiencylevels(Hartz,1996). Values

between600and800ppmnitrate-Nwhenplantsresumespringgrowthandpriortobloom,

fallingto300to500ppmduringbloomand200to500ppmduringharvestareconsidered

sufficient(Demchak,2012).Floridarecommendedpetiolenitrate-Nconcentrationsof600-800

ppmatfirstharvest(DeValerio,etal.2003).WhileNorthCarolinarecommendedpetiole

nitrate-Nconcentrationsbetween3,000-5,000ppmatfirstharvest(Hicks,2015).PlanttissueN

sufficiencyrangesforstrawberriesare3-4%(Bryson,etal.2014).

InorganicNfertilizersarecommonlyusedforsmallfruitproductionandeithercontain

nitrateorthefertilizerNsourceeventuallybecomesnitrateduetonaturalmicrobialactivity

(Bottoms,etal.2013).Nitrateissolubleinwaterandisweaklyretainedbythesoilduetothe

soilslowanionexchangecapacity.Nitrate,therefore,movesthroughthesoilatvirtuallythe

4

samespeedaswater.IftheproperamountofNfertilizerandproperirrigationregimesare

usedforcropproduction,thechancesofNleachingisreduced.AstudybyBruggemanetal.

(1995)suggestedthatmorethan63%oftheshallowwellsatadepthof75feetorless,in

NorthamptonCountyontheEasternShoreofVirginia,containnitrate-Nconcentrationsabove

naturalbackgroundlevelsof0.2ppm.Nitrate-Nlevelsabovetheassumednaturalbackground

concentrationweredefinedasnitratedetection.Theaverageconcentrationofthe131

sampledshallowwellswasalmost5ppm.Nitrate-NconcentrationsabovetheEPA’slifetime

HealthAdvisoryLevels(HALs)of10ppmwerefoundin17%ofsampledshallowwells.Ifproper

irrigationregimesareused,Nleachingisreducedkeepingsolublefertilizerintheplants’

effectiverootzoneof6inches(Gärdenäsa,2005).Therefore,reducingnutrientleachingby

utilizingappropriatefertilizationandirrigationprogramsisadesiredpracticeforstrawberry

productionandsupportsthecurrentbestmanagementpracticeeffortsforthestate.

ThepopularityoftheannualhillproductionsysteminthesoutheasternUnitedStates

andportionsoftheAtlanticseaboardareinfluencingthecultivarpicture.Commerciallygrown

cultivarsinNorthCarolinaandthemid-AtlanticareJunebearers(NCCooperativeExtension,

2012).Presently,strawberrygrowersareusingcultivarsdevelopedintheUniversityof

California,Davis,program,‘Chandler’and‘Camarosa’,orfromtheUniversityofFlorida

program,‘SweetCharlie’(Hokansonetal.,2000).Thesethreecultivarshavebeenselectedfor

acceptableyieldandmarketabilityinNorthCarolinaandthemid-Atlantic,extendingthe

harvestseasonoverasix-weekperiod,but,incooler-than-averagespringtemperatures,the

harvestcanlast2months(Poling,1993).‘Chandler’isthestandardcultivarforu-pickproducers

becauseofitshighyieldcomparedtootherplasticulturecultivars,coldhardiness,andbecause

5

itiswelllikedbyconsumersforitsgoodflavor,fruitsizeandattractiveredfruitcolor(NC

CooperativeExtension,2012).‘Camarosa’,anewercultivaronthemarket,hasverylargefirm

fruitandhassuperiorshelf-lifeandhandlingcharacteristicscomparedto‘Chandler’.However,

‘Camarosa’isnotascoldhardyas‘Chandler’,leadingtoyieldissuesincolderpartsofthemid-

Atlanticregion.InthewarmerwinterareasofNorthCarolina,‘Camarosa’productionnow

surpasses‘Chandler’inacreage(NCCooperativeExtension,2012).

Theobjectiveofthisstudywastoevaluateplantingdate’simpactonyieldfromcultivars

‘Camarosa’and‘Chandler’utilizinganannualhillproductionsystem.Additionally,fertilization

managementwasalsoanalyzedinresponsetooverallyieldandfruitqualityparameters.

MaterialsandMethods

Afieldexperimentwasconductedduringthe2012-2013growingseason.The

experimentalsitewaslocatedattheVirginiaTechEasternShoreAgriculturalResearchand

ExtensionCenter(AREC)inPainter,VA.ThesoilwasaBojacsandyloam(course-loamy,mixed,

thermicTypicHapludults)thatconsistedof65%sand,25%silt,and10%clayinthe0-6-inch

horizon(USDA-NRCS,2016).Thestudywasarrangedinafactorialarrangementof2cultivars

and3plantingdatesinarandomizedcompleteblockdesignwithfourreplications.

PlugtransplantsofJune-bearing‘Chandler’and‘Camarosa’varietieswereobtained

fromanOntario,Canadanursery.TransplantingoccurredonSept.21,28andOct.5,2012.

Plantsweresetthroughmethylbromidefumigated,blackpolyethylenemulchonastandard2

rowraisedbedspaced16inchesoncenter.Inthefieldsetting,polyethylenebedswerespaced

on5-ft.rowcenterswithdoublelinedripirrigationinstalledunderthemulch.Dripirrigation

wasusedtomeetplants’waterandfertilizerrequirements.TheVirginiaCommercialVegetable

6

ProductionRecommendations(Wilson,et.al.2012)werefollowedforwater,fertilizer,andpest

managementthroughouttheseason.Eachplotcontained40plants,withthecenter20plants

beingdesignatedforfreshfruitharvestandplantsampling.Fruitwithatleast75%redcolor

washarvested,graded,countedandweighedtwiceweeklyfrom14May2013throughthe3

June2013foratotalof7harvests.Marketablefruitwereconsideredfreeofrot,well-shaped,

andweighing8gormoreperfruit.

On2May2013atfirstflowerand9May2013atmid-flower,duringactivegrowing

daylighthours,10plantpetioleswerecollectedfromthemostfullyexpanded,mature,trifoliate

leavestomeasurepetiolenitrates.Petiolenitrate-NreadingswereanalyzedusingaLAQUA

TwinNitrateMeter(SpectrumTechnologies,Aurora,IL).Wholeleafsamplesofthemost-

recent,fullyexpandedtrifoliateleaffrom10plantsineachplotwerealsocollectedatmid-

flower(9May2013),driedat130°F,mini-groundtopassa0.425mmsieve,andanalyzedusing

aElementarVarioELCube(Hanau,Germany)forleaf%N,%carbon(C)andleaf%Susingdry

combustiontechniques(Elementar,2016).

Statisticalanalysisofthedatawasconductedusinganalysisofvarianceprocedures

(PROCGLM)(SASInstitute,2016)todeterminetheeffectofplantingdateandNconcentrations

astheyrelatedtostrawberrycultivar.MeanseparationswereconductedusingFisher’s

protectedleastsignificancedifference(LSD)testatthe10%significancelevel.Linearandnon-

linearregressionanalysiswasusedtocompareleaftissueandpetioleNconcentrationstoyield

andtocompareNtissuecomparisonmethodologies.

ResultsandDiscussion

7

Overallmarketablestrawberryfruityieldvariedbetween7,205and21,393lbs./acre;

whichistypicalformid-Atlanticproducerswithaveragedmarketableyieldsof20,000

lbs./acre(Poling,1993).Asignificantdifferencewasnotedwithaplantingdate×cultivar

interaction(p=0.0064).‘Camarosa’yieldedhigher(21,393lbs./acre)withtheSeptember21

earlyplantingdateascomparedtolaterplantingdatesandalsoyieldedhigherthanany

‘Chandler’plantingdate(Table1).Theearlysuccessof‘Camarosa’wasalsonotedinthe2005

SoutheastRegionalStrawberryPlasticultureProductionGuide,whereitstatedthatplanting

datesfor‘Camarosa’areaboutthesametimeas‘Chandler’,butmostgrowersprefertosetthis

cultivaratleastthreedaysaheadof‘Chandler’(Polingetal.,2005).Astheplantingdates

movedlaterintothefall,‘Camarosa’lostyieldwhiletheyieldfor‘Chandler’remainedconstant

(Table1).Thisresultisadirectresponsetothecoldhardinessof‘Chandler’whencomparedto

‘Camarosa’.

Whenputtingharvestpicknumberintothemodel,thefirstplantingdate(Sept.21)on

thefourthpickingyieldedthegreatestnumberofberriesharvestedwith‘Camarosa’(Table2).

Therefore,thebestoptionforgrowerstargetingtheearlyseasonu-pickmarketwouldbe

‘Camarosa’atanearlyplantingdate(Sept.21).Theearlyplantingdateof‘Camarosa’would

alsobeagoodchoiceforextendingtheu-pickseasonbecauseitstillhadahighernumberof

berriesharvestedthan‘Chandler’forthefinalharvestonthesameSept.21plantingdate(Table

2).However,ifthefarmerisgoingtoplantlate(Oct.5),‘Chandler’willhavemoreberrieslater

inthegrowingseasonthan‘Camarosa.’

Whencomparingyieldtoharvestpicknumber,thefirstplantingdate(Sept.21)hadthe

bestresultsforbothvarieties.Duringweektwoofharvest,picknumberfour,yieldedthe

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highestforbothvarieties;however,‘Camarosa’stillsignificantlyoutyielded‘Chandler’onthat

harvestdate(Table3).Eventhoughberrynumberwasdifferentduringthelastpick(Table2),

yieldoverallwasthesameacrossallplantingdatesandbothvarieties(Table3).Therefore,

growerssellingbythepoundorpercontainerwouldseenodifferenceregardlessofcultivaror

plantingdateiftheyarelookingtoextendtheseason.Overall,amaineffect,averagedacross

plantingdateandcultivarshowedthatberriesreachedmaximumsizeduringthefourthharvest

pickonthesecondweekofharvest(Table4)at22.63grams/berry;whichcorrespondedwith

highestyieldsforbothvarieties(Table3).Therefore,theendofthesecondweekofpickingis

optimalforplasticulturestrawberryproductionsystemsregardlessofplantingdateorcultivar.

Fortheplantingdate×cultivarinteraction,‘Camarosa’hadthelargestberriesoverall

treatmentsifplantedafterSeptember28(Table5).SimilartoFernandezetal.(2001)findings,

‘Chandler’producedstatisticallysmallerberriesthan‘Camarosa’.Kays(1998)statedthatwith

manyfruitsandvegetables,consumersdiscriminatebaseduponsize.Largerfruitaregenerally

preferredandtheverysmallfruitbeingleftunpicked.Asanindustrystandard,whenthe

averagefruitweightonaharvestdayfallsbelow8gperberryharvestscease(Weberetal.

2005).Althoughthereisaconcernregardingfruitsize,itwasobservedthatthefirstplanting

dateof‘Camarosa’hadthehighestfruityields,makingitamoredesirableplantingdateeven

thoughtheyweresmallerberries.Whencomparedtotheberriesof‘Chandler’onthatfirst

plantingdate,theberriesfrom‘Camarosa’wereequivalentinsizetherefore,‘Camarosa’isstill

agoodcultivaroptionforgrowersinthemid-Atlantic.Inallcases,theberrysizeswerelarger

thantheminimal8g/berrythresholdsuggestedbyWeberetal.(2005).

9

Leaftissuecollectedatmid-flowerhadnostatisticalimpactbasedoncultivarorplanting

date.OverallNandSaveraged3.02%and0.19%atflowering,respectively(Table6).Currently

acceptedstrawberryleaftissuesufficiencyrangesformatureleavesfromnewgrowthis2.10-

4.00%Nand0.15to0.30%S(Brysonetal.,2014).Therefore,inallcasesthe‘typical’fertility

andirrigationregimeutilizedaccordingtoVirginiaCooperativeExtensionrecommendations

providedsufficientwaterandfertilityforcropneeds(Wilsonetal.2012).FortheresultingC:N

andN:Sratios,C:Nwas15.54andN:Sratiowas15.61(Table6).AnelevatedN:S(>18:1)can

leadtopoorassimilationofeitherofthesenutrientsandoftencausesyellowingoftheleaves

(Hicksetal.,2015).However,wedidnotexperienceanyvisualleafdiscolorationinourstudy.

Petiolenitrate-Nreadingstakenatfirstfloweron2May2013indicatedthataplanting

date×cultivarinteractionwasnotsignificant;however,theplantingdatemaineffectwas

significant(p=0.0206).Petiolenitrate-NreadingsforplantsplantedonSeptember21(PD1;

1,563ppm)wereonaveragelowerwhencomparedtoSeptember28andOctober5plants

(PD2andPD3at2,238and2,688ppm,respectively;LSD0.10=479ppm).Therefore,plants

plantedduringthelaterplantingdateshadmorenitrate-Nintheplant’stissue;whichisneeded

forberryproduction.Nitrate-Navailabilityisnecessaryinthespringduringthevegetativeand

fruitingperiodtoincreaseyieldasstatedbyCasteel(2004).

Atmid-flower,on9May2013,‘Camarosa’hadoveralllowernitrate-Nconcentrations

comparedtohigherconcentrationsfoundin‘Chandler’(Table7).Wespeculatethat‘Chandler’

mayoverallbealoweryieldingcultivarwhencomparedto‘Camarosa’,since‘Chandler’has

highernitrate-Nconcentrationsatmid-flowerthan‘Camarosa’.However,furtherinvestigation

oftheyieldpotentialof‘Chandler’,asrelatedtonitrate-Nconcentrations,comparedto

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‘Camarosa’isneeded.BasedonUniversityofFlorida’ssufficiencyrangesforpetiolesaptesting

(DeValerioetal.2003),nitrate-Nlevelsforthisstudyexceededthesufficiencyranges(atfirst

harvest600-800ppm);therefore,fertigationcouldhavebeenreducedtoapplylessoverallN

basedonpetiolenitratetesting.Plantingdatehadnoeffectonnitrate-Ninteractionsinthe

secondnitrate-Nreadingsatmid-flower.

Anegativelinearregressionoccurredwhencomparingpetiolenitrate-Nconcentrations

andoverallyieldatbothpetiolenitratesamplings(Fig.3).AtourpracticedNfertilization

amounts,yielddecreasedaspetiolenitrate-Nconcentrationsincreasedabovethecurrently

acceptedsufficiencyrange(600-800ppm)(DeValerioetal.2003).Higheryieldingplanting

dateshadlowernitrate-Nconcentrations.Fittingwithsoilfertilitytheory,plantandyield

declineoccurredwhenoverfertilizationoccurred.TheworkingcurveinFig.3beginshigher

thantheUniversityofFlorida’srecommendednitrate-Nconcentrationsatharvest(DeValerioet

al.2003)andyieldsinthisstudywereeffectivelyreducedby2,082lbs.strawberries/acrewith

eachincremental500ppmpetiolenitrate-Nincrease(Fig.3).Albregtsetal.(1991)hadsimilar

findingsstatingthat,excessiveNfertilizationratesreducedyields,delayedripening,and

producedsoftfruit.Theyielddecreasewasnoticedatnitrate-Nconcentrationsat

approximately2,000ppmatmid-floweronthesecondreadingdateof9May2013.

AllleafSconcentrationswerebetween0.16–0.21%atfirstpick.Thesufficiencyrange

forleaf%Sis0.19-0.26%atinitialharvest(Brysonetal.2014).LeafNconcentration(Fig.4)

furthersupportsthetheorythatexcessNcouldleadtoareductioninyield,similartopetiole

nitrate-Ndata.SufficiencylevelsforleafNconcentrationsatinitialharvestarebetween3-3.5%

(Brysonetal.2014).Analysisofleaf%Ntonitrate-Nconcentrationsfromthefirstsamplingat

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initialfloweron2May2013,showedaweakcorrelationbetween%Nandnitrate-N(Fig.6).As

theleafNconcentrationincreasedby0.1%,yieldwasstatisticallyreducedby1,562lbs.

strawberries/acre.RegardingleafS(Fig.5),concentrationswereadequateanddidnotcausea

reductioninyieldasdemonstratedwithoverapplicationsofN.

Conclusions

Strawberrycultivar‘Camarosa’continuestooutperform‘Chandler’andisanindustry

standoutwhentransplantedintheearlyfallinthemid-Atlanticcoastalplainduetoitslarge,

firmfruitandpotentialyields.‘Camarosa’alsoprovidessuperiorearlyandlateseasonyields

andberryquantitycomparedto‘Chandler’.Regardingstrawberryfertility,farmersneedtobe

cognizantandproperlymonitorNstatusthroughoutthegrowingseason.Nitrogenisahighly

variablenutrientasitmovesreadilythroughouttheplant-soilsystem.Areductioninyield

occurredwhenexcessNwasplantavailableusingthecurrentacceptedNfertility

recommendationswithouryieldpotential.Overall,acceptedNfertilityrecommendationsfor

strawberryproductioninthemid-Atlanticneedsmoreevaluationalongwithin-seasonNstatus

monitoringandmeasurement.

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Table1.Plantyieldforaplantingdate(PD)×cultivarinteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic.

CultivarPlantingDate ‘Camarosa’ ‘Chandler’ --------------lbs./acre--------------Sept.21 21,393a† 10,270bcSept.28 13,016b 8,398cOct.5 7,205c 10,447bcLSD0.10 4,116†Meansfollowedbydifferentlettersaresignificantlydifferentacrossrowsandcolumns.

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Table2.Totalnumberofstrawberriesharvestedperharvestdateforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic

‘Camarosa’ ‘Chandler’Harvest Sept.

21Sept.28

Oct.5

Sept.21

Sept.28

Oct.5

---------------------------------berrynumber/acre------------------------------May14 13,403 14,241 12,398 22,785 25,131 12,231May17 68,523 32,670 19,267 25,466 20,942 24,125May20 90,639 45,738 26,639 38,534 23,288 44,062May24 146,261 57,968 33,340 62,827 42,722 59,811May28 116,774 86,115 25,298 54,953 33,676 36,859May31 97,675 23,958 14,743 43,728 39,707 60,816June3 35,016 11,560 9,215 21,277 17,089 28,817

LSD0.1028,521

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Table3.Yieldofstrawberriesperharvestdateforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic

‘Camarosa’ ‘Chandler’Harvest Sept.

21Sept.28

Oct.5

Sept.21

Sept.28

Oct.5

---------------------------------------lbs./acre-----------------------------May14 707 917 725 1,098 1,293 652May17 3,007 1,763 1,077 1,193 882 983May20 3,628 2,478 1,390 1,568 1,080 1,749May24 6,548 3,157 2,098 3,000 2,056 3,018May28 4,032 3,499 1,160 1,861 1,234 1,558May31 2,690 847 523 1,275 1,425 1,725June3 770 355 247 491 429 763LSD0.10 929

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Table4.Averageweightofstrawberriesperharvestforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic

Harvest Weight ----grams/berry----

1 23.472 20.883 20.274 22.635 17.106 14.847 11.09

LSD0.101.2103

Table5.Weightperberryforaplantingdate(PD)×cultivarinteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic

‘Camarosa’ ‘Chandler’ -----------grams/fruit----------Sept.21 16.8b† 17.0bSept.28 21.5a 18.1bOct.5 22.2a 17.6bLSD0.10 2.5 †Meansfollowedbydifferentlettersaresignificantlydifferentacrossrowsandcolumns.

16

Table6.Leaftissuenutrientconcentrationsatmid-flowerfor

sandyloamsoilsinthemid-Atlantic N† C S C:N N:S ------------------------------------%------------------------------Sept.21 3.02a 46.26a 0.198a 15.50a 15.26aSept.28 3.02a 46.05ab 0.192ab 15.34a 15.74aOct.5 2.90a 45.61b 0.184b 15.79a 15.82aLSD0.10 N/A N/A N/A N/A N/A†Sufficiencyrange=2.1%(Brysonetal.,2014)

Table7.PetioleNitrateReadingatmid-flower–APlantingDate(PD)×cultivarInteractionforplasticulturestrawberriesgrownonsandyloamsoilsinthemid-Atlantic

‘Camarosa’ ‘Chandler’ ---------------ppm---------------Sept.21 1600b† 2625aSept.28 1310b 3075aOct.5 2675a 2425aLSD0.10 770†Meansfollowedbydifferentlettersaresignificantlydifferentacrossrowsandcolumns.

17

Fig.1.Mid-AtlanticCoastalPlainoftheUnitedStatescomprisedmainlyofsandyloamsoilsinthetemperatezone.(Anonymous,2016).

18

Fig.2.Annualhillproductionsystemofstrawberriesonsandyloamsoil(NCSmallfruitandspecialtycropIPM,2010)

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23

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