Development of a Growing Degree Day Model for Plant Growth

DevelopmentofaGrowingDegreeDayModelforPlantGrowthRegulatorsOnUltradwarfBermudagrassPu=ngGreens

WendellJ.Hutchens1,WilliamC.Kreuser2,andJamesP.Kerns1

1DepartmentofEntomologyandPlantPathology,NorthCarolinaStateUniversity2DepartmentofAgronomyandHorLculture,UniversityofNebraska-Lincoln

Introduc*on

Plantgrowthregulators(PGRs)arefrequentlyappliedonultradwarfbermudagrasspu=nggreens.PGRsareoTenappliedtoincreaseballrolldistance(i.e.greenspeeds),reduceexcessiveclippingyields,allowforreducedmowing,andprovidemoreconsistentplayingcondiLons.PGRapplicaLonintervalsforultradwarfbermudagrasspu=nggreensarenotwellcharacterized.ThereisconcernthatPGRsareappliedtoofrequently,leadingtoincreasedbioLcandabioLcstresses.ManyultradwarfbermudagrasssamplessubmiXedtotheNCSUTurfDiagnosLcsLabfordiseasediagnosishaveoTenbeentreatedwithfrequent,highratesofPGRs.Growingdegreeday(GDD)modelsareusedtodeterminewhenchemicalsshouldbeappliedbasedonweatherpaXerns.GDDmodelshavebeenconstructedforPGRsoncoolseasonturfgrasses,butnotultradwarfbermudagrass.ThesemodelsarebeneficialtogolfcoursesuperintendentsallowingformoreaccuratePGRapplicaLonLmings.TwocommonPGRslabeledforultradwarfbermudagrasspu=nggreensincludetrinexapac-ethyl(PrimoMaxx)andprohexadionecalcium(Anuew).TheinfluenceofPGRsonballrolldistanceandturfqualityisvitalforgolfcoursesuperintendentsmanagingultradwarfbermudagrasspu=nggreens.

Objec*ves1.  DevelopgrowingdegreedaymodelsforvariousPGRs

2.  DetermineeffectsofPGRsonballrolldistanceandturfquality

DiscussionGrowingdegreedaymodelsrevealedthataverageapplicaLonintervalsare170.84GDDforAnuewatthe0.056g/m2rate,152.6GDDforAnuewatthe0.112g/m2rate,and215.13GDDforPrimoMaxxatthe118.294ml/m2rate

PGRsshouldnotbesolelyappliedonacalendarbasisApplicaLonsonAugust2,2016resultedinregulaLonunLllateSeptemberPGRapplicaLonshadminimalimpactonballrolldistance

PGRsonlyhadanegaLveeffectonturfqualityfor1-2weeksaTereachapplicaLon

GrowingDegreeDayModels

Fundingprovidedby

WheelerTurfResearchFarm•  StudyperformedfromJuly5,

2016-September27,2016atLakeWheelerResearchStaLoninRaleigh,NC

•  PGRsPrimoMaxx(118.294ml/m2)andAnuewattwodifferentrates(0.056g/m2and0.112g/m2)appliedonJuly5,2016andAugust2,2016

•  TreatmentsarrangedinaRCBDwith3replicaLons6mlm2

•  Clippingscollected2-3Lmesperweek

Methods

•  Clippingswereovendriedfor24hoursat60°C•  Sandwasseparatedusinganelectricrazortovibrateanovenpanpropped

ata~30°angleandclippingswereweighed

•  BallrollmeasurementsweretakenintwooppositedirecLonsusingaSLmpmeter®andturfqualitywasvisuallyassessed

•  DataanalysiswasperformedusingSASandgrowingdegreedaymodelswereconstructedusingSolverinMicrosoTExcel

•  GDDesLmatesusedabase10°Ctemperature

Anuewat0.056g/m2rate Anuewat0.112g/m2rate

PrimoMaxxat118.294ml/m2rate

Figure1.Surveyconductedfor~300golfcoursesuperintendents(GIEMediaInc.,2015)

References

“Controlledgrowth.”GolfCourseIndustry,30June2015,hXp://www.golfcourseindustry.com/arLcle/pgrs-063015-pgr-research-criLcal/.Accessed8Dec.2016.NCSUTurfPathology.Trivia4me!Whichsideofthis'Champion'bermudagrassgreenreceivedaPGRapplica4onrecently??.13June2015.TwiXer.hXps://twiXer.com/ncturfpathology.Accessed9Dec.2016.

Figure5.Anuewat0.056g/m2rategrowingdegreedaymodel Figure7.Anuewat0.112g/m2rategrowingdegreedaymodel

Figure6.PrimoMaxxat118.294ml/m2rategrowingdegreedaymodel

Figure2.UltradwarfbermudagrassontherightexhibiLngphytotoxicityfromarecentPGRapplicaLon(NCSUTurfPathology,2016)

Figure3.Sandsepara*ngmechanism

Figure4.Clippingcollec*on

PGR Rate JulyGDDInterval

JulyMaximumSuppression

AugustGDDInterval

AugustMaximumSuppression

AverageGDDInterval

AverageMaximumSuppression

Anuew 0.056g/m2 191.32 81% 150.35 80% 170.84 80.50%

Anuew 0.112g/m2 170.92 81% 134.27 87% 152.6 84%

PrimoMaxx 118ml/m2 281.21 73% 149.04 91% 215.13 82%

GrowingDegreeDayModelResults

Table1.ApplicaLonintervalsandmaximumsuppressionforeachPGR

b

a

c

aa

a

c

a

bc

abbc

c

ab

c

a

bb

b

aa

bb

a

aaa

a

aa

a

aa

a

a

aaaa

Figure8.EffectofPGRsonballrolldistance

Figure9.EffectofPGRsonturfquality

Anuew0.056g/m2 Anuew0.112g/m2

PrimoMaxx118.294ml/m2 Control

Figure10.Plot2weeksaTerapplicaLonofAnuewat0.056g/m2

rate

Figure11.Plot2weeksaTerapplicaLonofAnuewat0.112g/m2

rate

Figure12.Plot2weeksaTerapplicaLonofPrimoMaxxat118.294ml/m2rate

Figure13.Plot2weeksaTernoapplicaLonofPGR

50%more47.2%thesame

2.8%less

Grow

thRelaL

veto

Con

trol

GrowingDegreeDays

GrowingDegreeDaysGrowingDegreeDays

Grow

thRelaL

veto

Con

trol

Grow

thRelaL

veto

Con

trol