Do single, double or triple fungicide sprays differentially affect the grain quality in winter wheat?

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Field

Crops

Research

j o u r n a l h o m e p a g e :w w w . e l s e v i e r . c o m / l o c a t e / f c r

Do

single,

double

or

triple

fungicide

sprays

differentially

affect

the

grain

quality

in

winter

wheat?

Moussa

El

Jarroudi

_,

_Louis

_Kouadio

_,

_Jürgen

_Junk

_,

_Marco

_Beyer

_,

_Matias

_Pasquali

_,

Clive

H.

Bock

_,

_Philippe

_Delfosse

a_{UniversityofLiège,ArlonCampusEnvironnement,185AvenuedeLongwy,ArlonB-6700,Belgium}

b_{InternationalCentreforAppliedClimateSciences,UniversityofSouthernQueensland,WestStreet,Toowoomba,QLD4350,Australia}

c_{LuxembourgInstituteofScienceandTechnology,41RueduBrill,L-4422Belvaux,Grand-DuchédeLuxembourg}

d_{USDA-ARS-SEFTNRL,21DunbarRoad,Byron,GA31008,USA}

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received17June2015

Receivedinrevisedform12August2015

Accepted18August2015 Keywords: Sustainableagriculture Fungaldiseases Grainquality Fungicides

a

b

s

t

r

a

c

t

Foliarfungicidesinwheataretypicallyusedtosafeguardagainsteconomiclossesfromdiseases.Inthis

study,weassessedtheeffectsofthreefungicidesprayregimes[single,double,andtripletreatments]on

fourdifferentgrainqualityparameters[thousandgrainweight(TGW),testweight(TW),grainprotein

content(GPC),andZelenysedimentationvolume(ZSV)]duringthe2006–2009periodattwositesin

Luxembourg.Thefungicidesusedweregenerallyamixofchlorothalonilandtriazoles.AtBurmerange,

(cultivarCubus),thevaluesofTGW,TW,GPCandZSVrangedfrom38to62g,67to83kghl−1,12.0%

to14.7%drymatter(DM),and27to54ml,respectively.Whereas,atEverlange(cultivarAchat),the

rangesofTGW,TW,GPCandZSVwere42to65g,65to81kghl−1_{,11.0%to15.0%DM,and21to66ml,}

respectively.Inmorethan75%cases,theresultsindicatethatfungicidesdidnotsignificantlyaffectTW

orZSVateithersites(P>0.05).However,therewasasignificantandpositivefungicideeffectonGPC

in2006and2009atBurmerange,andonlyin2006atEverlange(P<0.05).Onthecontrary,TGWwas

significantlyaffectedatBurmerangeinallyears,except2008whenapositiveincreasewasobserved

comparedtocontrolplots;andin2006and2007atEverlange.Interestingly,whentherewasaneffectof

fungicidesonaqualityparameter,therewasnodifferenceamongdifferentfungicidetreatments.Thus

underconditionsprevailinginLuxembourg,asinglefungicidetreatmentappliedwithjudicioustiming

generallyresultedinstatisticallysimilargrainqualityparameterswhencomparedwithadoubleortriple

fungicidetreatment.

©2015ElsevierB.V.Allrightsreserved.

1. Introduction

Wheatisoneofthetopthreestaplefoodsintheworld(next toriceandmaize),withatotalproductionestimatedas700 mil-lionmetrictonsin2013(FAO,2014).InLuxembourg,winterwheat (TriticumaestivumL.)isthemajorcerealcrop,accountingfor21%of thearablelandplantedin2013(Ministèredel’Agriculture,2014). Generally,theprofit ofwinter wheatcroppingrelies upon sus-tainedhighgrainyieldsandproductionovermany years,while maintaininghighqualitygrain.Commonwheatqualityparameters includeproteincontentandquality,specificweight,grain hard-ness,thousandgrainsweight,Hagbergfallingnumber, moisture content,sedimentationvolumeandforeigncontaminants.Wheat istypicallymilledintoflourwhichisusedtomakeawiderange

∗ Correspondingauthor.Fax:+352470264.

E-mailaddress:philippe.delfosse@list.lu(P.Delfosse).

offoods(e.g.,bread,semolina,cerealbars,confectionery,etc.).In Luxembourg,abouthalfofthewheatproductionisdedicatedto breadmaking(36001metrictons) andtheotherhalftoanimal feed(34726metric tons)(2014 data;Ministèredel’Agriculture, 2014).Therefore,thequalityofthegrainhasamajorinfluence onthemarketvalueofaparticularharvest;sofarmersseekand employeconomicallysustainablemeanstoensurethebest produc-tion,withsometimesinsufficientattentionpaidtoenvironmentally friendlyagronomicpractices.

Apart from unpredictable adverse environmental conditions (e.g.,frosteventsduringcriticalphenologicalstages,strongwinds, hailandperseverativerainyperiodsduringmaturationandharvest, etc.),fungaldiseasesarethemajorissuesthatcannegativelyimpact potentialgain,eitheringrainyieldorresultingfinancialreturn, inwinterwheatcropsinLuxembourg(ElJarroudietal.,2012b). Yieldlossescausedbyfungaldiseasesareaffectedbydisease sever-ity,theincidenceand timingofoccurrence,andthedurationof theepidemic(Teng,1983;Gaunt,1995;Oerke,2006;ElJarroudi http://dx.doi.org/10.1016/j.fcr.2015.08.012

Table1

AgronomicinputinformationforwinterwheatexperimentsconductedattwositesinLuxembourgduringthe2006–2009croppingseasons.

Site Year Cultivar Sowingdate Harvestdate MineralNfertilization(kgha−1)

Burmerange 2006 Cubus 30September2005 19July2006 192

2007 Cubus 11October2006 26July2007 192

2008 Cubus 6October2007 5August2008 228

2009 Cubus 6October2008 29July2009 228

Everlange 2006 Achat 10October2005 7August2006 225

2007 Achat 10October2006 26July2007 195

2008 Achat 8October2007 5August2008 195

2009 Achat 13October2008 6August2009 195

etal.,2012b).Themainfungaldiseasesofincreasingconcernin LuxembourgincludeSeptorialeafblotch(SLB,causedby Zymosep-toriatritici(Desm.)Quaedvlieg&Crous),leafrust(WLR,causedby PucciniatriticinaRoberge exDesmaz.),powdery mildew(WPM, caused byBlumeria graminis DC. f.sp. tritici em. Marchal), and Fusariumheadblight(FHB,primarilycausedbyFusarium gramin-earum)Schwabe(ElJarroudietal.,2012b).Beyondreducingyield, Fusariumspeciesreducethequalitybyreleaseoftoxicsecondary metabolitesinthegrainandbymodifyingtheaminoacidprofileof winterwheat(BeyerandAumann,2008).Toensurebeneficial out-comesintheirfarmingpractice,Luxemburgishfamerstypicallyuse stressanddiseaseresistantcultivars,inconjunctionwithsuitable managementpractices(forexample,croprotation).Nonetheless, preventivefungicide applications are needed toprotect winter wheatcropsfromfungaldisease,particularlyonthethreeupper leavesthatcontributethemosttothefinalyield;generallytwoto threefoliarfungicidetreatmentsareappliedduringthecropping season.Withthepotentialenvironmentaldamagecausedby over-and/ormisuseofagrochemicalsinprotectingwinterwheatagainst fungaldiseases,warningbulletinsbasedonadecisionsupport sys-tem(DSS;PROCULTUREandadd-ons;ElJarroudietal.,2009,2014, 2015), andavailablefromvariouswebsites(forexample,http:// www.centralpaysanne.lu,http://www.agrimeteo.lu, http://www. lwk.lu/mediathek),havebeenissuedweeklythroughoutthe grow-ingseasoninLuxembourgforthelastdecade,inordertoprovide farmerswithinformationregardingdiseaserisk,theneedtospray fungicides,theoptimumtiming,andthuscontrolfungaldiseases inaprofitableandmoreenvironmentallyfriendlyway(ElJarroudi etal.,2013,2015).

Severalstudieshavedealtwiththeeffectsoffoliarfungicides onthequalityofwheatgrain(Goodingetal.,2000;Kelley,2001; DimmockandGooding,2002a;Wangetal.,2004;Blandinoetal., 2009;BlandinoandReyneri,2009;Fernandezetal.,2014;Rodrigo etal.,2015).Inthesestudies,althoughonetothreefungicide appli-cationswerecompared,atmosttwofungaldiseases(i.e.,FHBand SLB)weretargeted.Theexperimentaimswereprimarilyto ascer-tain fungicide efficacy, while the timing of an optimum single fungicidetreatmentreceivedonlypartialornoattention.In fur-therexperiments,ElJarroudietal.(2015)reportedthatadouble ortriplefungicidetreatment(usingmixesofstrobilurinsand tri-azoles)didnotnecessarilyincreasethefinancialreturncompared toasinglefungicidetreatmentduetoonlymilddiseasesseverities developingonthethreeupperleavesduringgraindevelopment. Additionally,inyears withnoseverefungaldisease,thedouble and/ortriplefungicidetreatmentcouldbeavoidedentirelywhen followingtherecommendationsofthedecisionsupportsystem(El Jarroudietal.,2015).Inordertogainmoreinsightstominimizing andoptimizingfungicideapplications,weaskedthequestion:does adouble ortriplefungicidetreatmentsignificantlyimprovethe qualityofwinterwheatgraincomparedwithasingle,judiciously appliedfungicidespray(i.e.,determinedthroughadecisionsupport system)asthesinglefungicideapplicationisaimedtomaximize diseasecontrolwhileminimizingpotentialharmfulimpactsonthe environmentthus,providingthegrowerwithsustainablefinancial

returns?Theobjectiveofthisresearchwastoestablishwhether thereweredifferencesinfourwheatgrainqualityparameters[i.e., thousandgrainweight(TGW),testweight(TW),grainprotein con-tent(GPC),andZelenysedimentationvolume(ZSV)]fromwinter wheatfieldstreatedwitheitherone,twoorthreefungicidesprays.

2. Materialandmethods

2.1. Experimentalfields

Fieldexperimentswereconductedattwosites[i.e.,Burmerange (49◦29N,6◦19E,248mabovemeansealevel(amsl))andEverlange (49◦46N,5◦57E,309mamsl)]during2006–2009.Theexperiments weredesigned ina randomizedblock withfourreplicates(one replicateplot=12m2_{);eachreplicateblockconsistingoffungicide} treatedandnon-treated(control)plots.Newplotswereselected eachyearinthesamelocationstomaintainacroprotationsystem. Agronomicinputsandcrophusbandryweretypicalfora Luxem-bourgishfarm(Table1).Nitrogenfertilization,apracticeknown tohaveinfluenceongrainqualityparameters(Ruskeetal.,2004), wassplitasfollows:allplotsreceived40–70kgNha−1,intheform ofammoniumnitrate,atgrowthstage(GS)25(mainshootand 5tillers;Zadoksetal.,1974),followedby60–70kgNha−1atGS32 (secondnodedetectable),andafinalapplicationof65–95kgNha−1 atGS59(emergenceofinflorescencecompleted).Duringthe4-year period,three fungicidetreatments werecomparedat eachsite: asingleapplication(1T) basedonadecisionsupportsystem(El Jarroudietal.,2015),adouble(2T)andatriple(3T)spray applica-tion,alongsidecontrolplots(0T).Thefungicidesused,alongwith thegrowthstageatwhichtheywereappliedarereported(Table2). Variousfungaldiseases(i.e.,SLB,WLR,WPM,FHB,andstripe rust)weremonitoredweeklyfromGS29–30toGS85.Estimatesof fungaldiseaseseverityweremadeonthesame10plantsincontrol plotsthroughoutthegrowingseason,andbi-weeklyon10 ran-domlyselectedplantsineachofthetreatedplots.FHBseveritywas monitoredthreeweekspost-anthesisforyear2007and2008by countingthenumberofsymptomaticspikeletsperheadonatotal of100–200plants(Giraudetal.,2010).

Themeteorologicaldata(minimum,maximumand meanair temperatures, precipitation, and relative humidity) were auto-matically retrieved from a web-based database system (www. agrimeteo.lu),processedusinganautomaticdataprocessingchain forqualitycheckingandgapfilling,andprovidedatanhourly res-olution(Junketal.,2008).Fromthestartofthediseasemonitoring period, aforecast of weather conditions covering thefollowing sevendayswasusedforpredictingthetimepointforthesingle fungicideapplication(fordetailsseeElJarroudietal.,2015and Referencestherein).

2.2. Grainqualityparameters

TheperiodofwinterwheatharvestinLuxembourgspans mid-JulytothebeginningofAugust(Zadoks’growthstage92andall leavessenesced,Table1).Grainyieldswereobtainedby

harvest-Table2

Wheatgrowthstages(Zadoksetal.,1974),commercialbrandsanddosesoffungicidesusedforthesingle(1T),double(2T)andtriple(3T)fungicide-treatedplotsatthe

experimentalsitesduringthestudyperiod.

Treatment Year Growthstage(GS)atfungicideapplication Fungicidea

1T Allyears –b _1.60lha−1_Input®_{proset+1.00lha}−1_Bravo®

2T 2006

and 2007

GS31 0.75lha−1_Opusteam®_+1.00lha−1_Bravo®

GS59 1.60lha−1_Input®_{proset+1.00lha}−1_Bravo®

2008 and 2009

GS31 0.75lha−1_Opera®_+0.80lha−1_Input®_{proset+1.00lha}−1_Bravo®

GS59 1.50lha−1SwingGold®_+1.00lha−1_Bravo®

3T 2006

and 2007

GS31 0.70lha−1Stereo®_+1.00lha−1_Bravo®

GS37 1.60lha−1_Input®_{proset+1.00lha}−1_Bravo®

GS59 0.75lha−1_Opusteam®_+1.00lha−1_Bravo®

2008 and 2009

GS31 0.70lha−1_Stereo®_+1.00lha−1_Bravo®

GS37 0.75lha−1_Opera®_+0.80lha−1_Input®_{proset+1.00lha}−1_Bravo®

GS59 1.50lha−1SwingGold®_+1.00lha−1_Bravo®

a_{TheproductsOpusteam}®_,Bravo®_,Input®_proset,Opera®_,SwingGold®_,andStereo®_{,containtheactiveingredientsepoxiconazole(84g/l)+fenpropimorph(250g/l),}

chlorothalonil(500g/l),prothioconazole(250g/l)+spiroxamine(500g/l),epoxiconazole(50g/l)+pyraclostrobin(133g/l),epoxiconazole(50g/l)+dimoxystrobine(133g/l),

andcyprodinil(250g/l)+propiconazole(62.5g/l),respectively.

b_{Thesinglefungicideapplicationwasdeterminedthroughadecisionsupportsystem(ElJarroudietal.,2015).Thegrowthstagesatwhich1Twasappliedwere:GS37in}

2006,GS45in2007and2009atBurmerange;GS37in2006,2007and2009atEverlange.No1Twasappliedin2008atbothsites.

ingwithanautomatedreaper(WintersteigerAG,Austria).Grain samplesfromeachplotateachlocationwerecollected(andtagged topreservetheiridentity)forthedeterminationofthousandgrain weight(TGW),testweight(TW),grainproteincontent(GPC),and Zelenysedimentationvolume(ZSV).Carewastakenastoensuring thatallsamplingcontainersinwhichthesampleswereplacedwere clean,dryandfreefromcontaminants,andstoredtoensuresample preservation.Allthelaboratoryanalyseswerecarriedoutwithin oneweekafterthesamplescollection.TGWwasdeterminedbased onasampleofcleangrains(250gminimum).Aminimumoftwo replicatesof200cleangrainswerecountedusingaseedcounter andweighedtodeterminetheweightof1000kernels.Weights wereexpressedat14%moisturebasis(typicalhumiditypercentage inmarketedwinterwheatinLuxembourg).TWwasdeterminedby

AACC(AmericanAssociationofCerealChemists)approvedmethod 55-10(AACCInternational,2000).TWresultswerereportedin kilo-gramsperhectolitre(kghl−1).GPCandZSVweredeterminedbyICC standardmethods202and116/1,respectively(ICC,2003). 2.3. Statisticalanalysis

AlldataanalysesweredoneinSAS®_{UniversityEditionv9.4(SAS} InstituteInc.,Cary,NC).Thetreatmenteffectsoneachofthe qual-ityproperties(TGW,TW,GPCandZSV)ateachlocationandyear weresubjecttoanalysisofvariance(ANOVA)usinggenerallinear modelling(PROCGLMprocedure).Grainqualityparameterswere considereddependantvariables,andyearandfungicidetreatment wereindependentvariables.ATukey’sHSDposthocmeans

sepa-Fig.1. MeanseverityofSeptorialeafblotch(SLB),wheatleafrust(WLR)andwheatpowderymildew(WPM)betweenGS77andGS87(Zadoksetal.,1974)attheexperimental

sitesinLuxembourgduring2006–2009.Diseaseseveritiesarepresentedforthesingle(1T),double(2T)andtriple(3T)fungicide-treatedandcontrol(0T)plots(nofungicide

sprayapplied).ThemeanvaluewascalculatedonthetwoupperleavesL1andL2,L1beingtheflagleaf.LuxembourgwasexposedtoaFusariumheadblight(FHB)outbreak

rationtest(˛=0.05)wasusedtocomparethemeans.Anypairwise P-values<0.05(2-sided)wereconsideredsignificant.

3. Results

3.1. Weatherconditionsanddiseasepressureatthestudysites Over the 2006–2009 period, different weather conditions occurredfromMaytoJulyateachofthestudysites(Table3). Fre-quentprecipitationeventsoccurredduringMayatbothsitesinall years,except2008(thehighestnumberofrainydayswasobserved inJuneatEverlange,withregularbutlowerfrequencyofrainfall atBurmerange).Suchrainyconditions,associatedwithfavorable airtemperaturesandrelativehumidity,supportthedevelopment offungaldiseasesontheupperleaves,whichinturncan nega-tivelyimpactthefinalgrainyield.Betweenthetwosites,Everlange hadmorerainfallamountovertheMay–Julyperiod(260mmon average,comparedto189mmatBurmerange).During the2006 and 2009 growing seasons, June growing degree days (GDDs) rangedfrom466to511degreedayand 488to533degreeday atBurmerangeandEverlange,respectively.(Table3).HighGDDs inJunecanacceleratetheleafsenescenceprocessandthusreduce thegrainfillingperiod,whichoccursinJuneattheexperimental sites(ElJarroudietal.,2012b).

Twofungaldiseases,SLBandWLR,werepredominantduring 2006–2009,with2007beingtheyearwithmostsevereSLB(Fig.1). Indeed,meanSLBseveritywas75%innon-treatedplotsduringthe GS77–87period.In2007FHBwasalsosevereinthewhole coun-trywiththehighest severity(61%ofsymptomaticspikeletsper infectedhead)foundatBurmerange.Verylowseverityofother fungaldiseaseswasrecordedduringthissameperiodontheupper leaves.Thefungicideapplicationsensuredprotectionagainst dis-easeonwinterwheatattheexperimentalsitesoverthe2006–2009 period(ElJarroudi etal.,2012b).In 2008,theincidenceof fun-galdiseases wasverylow atEverlange andalmostnegligibleat Burmerange.Therewasnosingletreatment(1T)recommendedby theDSS(Fig.1).

3.2. Grainyieldsandgrainqualityparameters

Theinter-annualvariationofwheatgrainyieldsfromwinter wheatreceivingdifferentfungicidetreatmentsappliedisshown inFig.2.Overall,fungicideapplicationsresultedinhighergrain yieldsatboth sitesin allyears compared withthenon-treated plots,exceptin2008whenfungaldiseasepressurewaslowand yieldswere in the same range for the 0T, 2T and 3T plots. At Burmerange,grainyieldsshowedasimilarrangefor2006–2007 and2009(8–13tonsha−1,Fig.2),exceptin2008,ayearneither conducivefordiseaseincidencenorforreachinghighandstable grainyieldbecauseseveralplotswereexposedtolodging.At Ever-lange,thegrainyieldsremainedinthesamerangeoverthestudy periodforallplots,althoughtherewasadeclinein3Tplotsin2008. TheANOVAcomparingtheeffectsoffungicidetreatmentsongrain yieldhasbeendiscussedpreviously(ElJarroudietal.,2015).Here aretherelevantresultsforthecurrentstudy:(i)fungicide treat-mentsresultedinhighergrainyieldssignificantlydifferentfrom thatof0Tplots(P<0.05)atbothsitesandinallyearsinvolvingthe threefungicidetreatmentstrategies(1T,2T,and3T),exceptin2006 atBurmerange(meanyieldsfrom1Tand0Tplotswereinthesame rangeandstatisticallysimilar),andin2007atEverlange(2Twas statisticallysimilarto0T);(ii)in2008(no1Tapplied)no signifi-cantdifferencewasobservedbetweenthefungicidetreatedplots andthecontrolplots;(iii)meangrainyieldswerenotsignificantly differentin2009atEverlange.

Grainqualityparametersdidvarybyyearandfungicide treat-ment during the2006–2009 period. At Burmerange thevalues

of TGW,TW, GPC and ZSV (all years and fungicide treatments Table

3 Monthly cumulated precipitation, rainy days and growing degree days (GDD) from May to July 2006–2009 at two experimental sites in Luxembourg. Growing degree days are calculated on a base temperature of >0 ◦C; a rainy day is defined with daily total precipitation >1 mm. Site Year 2006 2007 2008 2009 Month Precipitation (mm) Rainy days (d) GDD ( ◦C d − 1) Precipitation (mm) Rainy days (d) GDD ( ◦C d − 1) Precipitation (mm) Rainy days (d) GDD ( ◦C d − 1) Precipitation (mm) Rainy days (d) GDD ( ◦C d − 1) Burmerange May 99 21 402 88 16 446 36 7 488 64 6 432 June 37 5 511 134 19 511 36 7 505 49 7 466 July 7 2 713 68 15 524 67 7 561 73 15 564 May–July 143 28 1626 290 50 1481 139 21 1554 186 28 1462 Everlange May 113 18 425 110 14 467 122 11 490 63 15 443 June 77 8 533 141 15 541 70 21 529 93 9 488 July 52 5 716 72 6 541 61 13 567 71 19 580 May–July 242 31 1674 323 35 1549 253 45 1586 227 43 1511

Fig.2.DistributionofwheatgrainyieldfordifferentfungicidetreatedplotsattwoexperimentalsitesinLuxembourgoverthe2006–2009growingseasons.1T–3Trefertothe single,double,triplefungicidetreatedplots;0Tarecontrolplots(i.e.,nofungicidesprayapplied).Thetopandbottomoftheboxesrepresentthe25thand75thpercentiles; thewhiskersarethetwolinesoutsidetheboxthatextendtothehighestandlowestdatavalues.Themedianisrepresentedbythickhorizontallineswithinthebox.

included)ranged,respectively,from38to62g,67to83kghl−1,

12.0% to 14.7% dry matter (DM), and 27 to 54ml (Fig. 3).TW

andGPCwerehighestin2006,regardlessoffungicidetreatment. GPCvalueswerethelowestoverthestudyperiodin2007 (val-ues<13%,overalltreatments).Ontheotherhand,TGWandZSV werehighestfor2008.The2008yearwasnotfavorabletoreach highyieldbecauseofheterogeneouslossesgeneratedbylodging. Thismighthavecontributedtovariableresponseintermsofwheat grainquality,especiallyforTGWandZSVasassessedbythe dis-tancebetweenwhiskersin box plots (Fig.3).At Everlange,the rangesofTGW,TW,GPCandZSV(all yearsandfungicide treat-mentsincluded)were42–65g,65–81kghl−1,11.0–15.0%DM,and 21–66ml,respectively(Fig.4).TGWandTWvalueswerequite sta-bleduringthe4-yearperiod,although2009valueswereslightly lowerandhigher,respectively.GPCandZSVvaluesvariedoverthe entirestudyperiod,withthehighestvariabilityobservedforthe twoparametersin2006.

3.3. Fungicideeffectsongrainqualityparameters

3.3.1. Differencesbetweentreatments,yearsandinteractions Overall,thefungicidetreatmentandyeareffectswere signifi-cantforallthegrainqualityparametersanalyzedatBurmerange (P<0.002;Table4).AtEverlange,theyeareffectwasalsosignificant forallqualityparameters(P<0.0001),whilethetreatmenteffect wassignificantonlyfor TGWandZSV(P<0.0001and P=0.005, respectively).Nosignificantdifferencewasfoundbetween treat-mentsforTWorGPC.Significanteffectofyearduringthestudy period couldbe ascribedto thevariability in weather. Interac-tionsof treatment×year(Table4)were notsignificant forany grainqualityvariableatEverlange(P>0.05);butweresignificant atBurmerangeforallvariables(P<0.05),exceptTW(P=0.6). 3.3.2. Differencesbetweentreatmentsforeachyearatbothsites 3.3.2.1. Burmerangesite. In2008therewasnosignificant differ-encebetweentreatmentsforTGW(P=0.7;Table5).Likewise,the meanvaluesofTWwerenotsignificantlydifferentin2007–2009 betweentreatments, andGPC wasnot significantly differentin 2007and2008(P>0.05).ZSVwassignificantlydifferentbetween treatmentsonlyin2009(P<0.05;Table5).Inyearswhena

sig-nificanteffectof fungicide treatmentswasobserved, there was an increase in the mean values of allquality parameters from treated plots comparedto controlplots (Table 6).More impor-tantly,inthoseyearsandforTGWandTWparameters(i.e.,2006, 2007and 2009for TGW; 2006for TW), themean values were statisticallysimilaramongtheplotsreceivingdifferentfungicide treatments—1T–3T.RelativelyhighermeanTGWwasobservedin 2Tand3Tplotscomparedto1Tplotsin2009(43.3gfor1Tplots, and 46.3and 46.4gfor2T and3T plots,respectively); whilein 2006and2007,thedifferenceofmeanTGWbetweenthe fungi-cidetreatedplotsdidnotexceed2g(Table6).WithrespecttoGPC, themeanvaluesdifferedsensiblyinthefungicide-treatedplots(at most0.4%DMofdifference)in2006and2009,withamarked posi-tiveGPCincreasein2Tplots(+0.3to+0.6%DM)comparedto1Tand 3Tplotsin2009.Thedifferencewasaslittleas0.3%DMbetween 1Tplotsand3Tplotsinthisyear.FormeanZSVvalues,however, fungicideapplicationssignificantlyincreasedthemeanvaluesin onlyoneyear(2009),withamarkeddifferencebetween2Tand 3Tplots ononeside,and 0Tand1Tplotsontheother.For the remainingyears(2006–2008),whiletherewasnosignificanteffect offungicidetreatment,acleartrendofincreaseordecrease associ-atedwithfungicideapplicationswasobserved(meanZSVvaluesin controlplotsoftenhigherthanthosefromtreatedplots;Table6), furthersuggestingthatthenumberoffungicidesprayshadlittleor noimpactonthevariable.

3.3.2.2. Everlange site. TheANOVA (Table 5)showed significant differencesonly forTGWin2006and 2007(P=0.01and 0.001, respectively).Ofthe4years,asignificantdifferenceamong treat-ments for GPC and ZSV wasobserved only in 2006and 2007, respectively(P=0.03and0.03,respectively).Fungicidetreatments didnotimprovetheTWofwheatgrains(Table6).MeanTGWvalues weresimilarwithinfungicidetreatedplots,butdistinctfromthose ofthenon-treatedplotsin2006and2007,althoughin2006TGW fromthe1Tand0Tplotswerestatisticallythesame.Similarresults wereobservedformeanGPCvaluesin2006.MeanGPCwasnot affectedbyfungicidetreatment,buttheGPCwasgreateringrain fromthe2Ttreatedplotscomparedwiththenon-treatedcontrol. In2007the1TtreatmentresultedinlowerZSVvaluescompared tothe3Ttreatment(the2T–0Ttreatmentsweresimilar;Table6).

Fig.3.Burmerange—variabilityofthethousandgrainweight(TGW),testweight(TW),grainproteincontent(GPC),andZelenysedimentationvolume(ZSV)accordingto

thefungicidetreatmentduringthe2006–2009growingseasons.1T–3Trefertothesingle,double,triplefungicidetreatedplots;0Tarecontrolplots(i.e.,nofungicidesprays

applied).Thetopandbottomoftheboxesrepresentthe25thand75thpercentiles;thewhiskersarethetwolinesoutsidetheboxthatextendtothehighestandlowestdata

values.Themedianisrepresentedbythickhorizontallineswithinthebox.

Table4

Generallinearmodelanalysisoftheeffectsofyearandfungicidetreatmentonthousandgrainweight(TGW),testweight(TW),grainproteincontent(GPC),andZeleny

sedimentationvolume(ZSV)duringthe2006–2009periodatBurmerangeandEverlange.Theanalysiswasperformedondataincludingyearswhenthesinglefungicide

treatmentwasapplied(i.e.,2008excluded).

Site Effect TGW TW GPC ZSV

DFa _{F-value Pr>F}b _{F-value Pr>F F-value Pr>F F-value Pr>F}

Burmerange Treatment 3 41.0 <0.0001 6.2 0.002 10.2 <0.0001 15.3 <0.0001 Year 2 13.1 <0.0001 172.2 <0.0001 160.2 <0.0001 108.3 <0.0001 Treatment×year 6 3.1 0.02 0.8 0.6 2.9 0.02 3.0 0.02 Everlange Treatment 3 15.1 <0.0001 1.2 0.3 2.9 0.05 5.1 0.005 Year 2 19.0 <0.0001 57.5 <0.0001 491.2 <0.0001 449.9 <0.0001 Treatment×year 6 1.3 0.3 1.7 0.1 1.0 0.4 1.8 0.1 a_{Degreeoffreedom.}

Fig.4. Everlange—variabilityofthethousandgrainweight(TGW),testweight(TW),grainproteincontent(GPC),andZelenysedimentationvolume(ZSV)accordingtothe

fungicidetreatmentduringthe2006–2009growingseasons.1T–3Trefertothesingle,double,triplefungicidetreatedplots;0Tarecontrolplots(i.e.,nofungicidesprays

applied).Thetopandbottomoftheboxesrepresentthe25thand75thpercentiles;thewhiskersarethetwolinesoutsidetheboxthatextendtothehighestandlowestdata

values.Themedianisrepresentedbythickhorizontallineswithinthebox.

Table5

Generallinearmodelanalysisoftheeffectsoffungicidetreatmentonthousandgrainweight(TGW),testweight(TW),grainproteincontent(GPC)andZelenysedimentation

volume(ZSV)byyearduringthe2006–2009periodatBurmerangeandEverlange.

TGW TW GPC ZSV

F-value Pr>Fa _{F-value Pr>F F-value Pr>F F-value Pr>F}

Burmerange 2006 9.1 0.002 10.6 0.001 4.9 0.02 3.7 0.04 2007 17.5 0.0001 1.7 0.2 0.7 0.6 1.4 0.3 2008 0.4 0.7 0.2 0.8 1.4 0.3 0.4 0.7 2009 16.6 0.0001 2.7 0.09 16.0 0.0002 42.4 <0.0001 Everlange 2006 5.5 0.01 2.7 0.09 4.4 0.03 2.9 0.08 2007 10.3 0.001 1.3 0.3 1.0 0.4 4.4 0.03 2008 0.7 0.5 0.4 0.7 1.3 0.3 1.8 0.2 2009 1.7 0.2 1.8 0.2 1.3 0.3 2.3 0.1

Note:Nosinglefungicidetreatmentwasappliedin2008atbothsites.Thedegreeoffreedom(DF)is3forallyearsexcept2008(DF=2).

Table6

Meanvaluesofwheatgrainqualityparameters(i.e.,thousandgrainweight,testweight,grainproteincontentandZelenysedimentationindex)byyearforthesingle(1T),

double(2T)andtriple(3T)fungicidetreatedandcontrol(0T)plotsduringthe2006–2009growingseasonsatBurmerangeandEverlange.Meanswiththesameletterarenot

significantlydifferent(˛=0.05).

Burmerange Everlange

Thousandgrainweight(g)

2006 2007 2008 2009 2006 2007 2008 2009 1T 44.2AB 48.3A n.a 43.3A 1T 52.7AB 55.3A n.a 50.8A 2T 45.4A 48.3A 54.4A 46.3A 2T 53.2A 54.9A 55.5A 50.7A 3T 46.2A 48.9A 54.7A 46.4A 3T 53.3A 57.5A 57.4A 51.5A 0T 42.3B 40.7B 52.2A 39.4B 0T 49.6B 49.9B 55.7A 48.5A MSDa _{2.4 3.9 8.7 3.4 MSD 3.1 4.2 4.9 4.2} Testweight(kghl−1₎ 2006 2007 2008 2009 2006 2007 2008 2009 1T 83.0A 70.8A n.a 74.9A 1T 76.8A 75.6A n.a 78.6A 2T 83.1A 72.9A 75.5A 78.2A 2T 77.0A 74.7A 78.0A 80.2A 3T 83.3A 72.5A 76.5A 77.9A 3T 77.0A 76.7A 77.5A 79.7A 0T 81.6B 70.8A 76.2A 74.5A 0T 76.3A 75.2A 77.5A 80.2A MSD 1.0 3.6 3.9 4.9 MSD 0.8 3.2 2.0 2.5

Grainproteincontent(%drymatter)

2006 2007 2008 2009 2006 2007 2008 2009 1T 13.8AB 12.3A n.a 13.0BC 1T 13.8AB 14.4A n.a 11.1A 2T 14.2AB 12.5A 13.7A 13.6A 2T 14.0A 14.6A 13.1A 11.6A 3T 14.2A 12.5A 13.9A 13.3B 3T 13.8AB 14.6A 13.0A 11.6A 0T 13.6B 12.6A 13.7A 12.8C 0T 13.5B 14.6A 12.9A 11.4A MSD 0.6 0.5 0.5 0.4 MSD 0.4 0.5 0.4 0.8

Zelenysedimentationvolume(ml)

2006 2007 2008 2009 2006 2007 2008 2009 1T 33.3A 43.0A n.a 44.5B 1T 42.8A 57.3B n.a 25.5A 2T 38.8A 45.0A 51.3A 50.3A 2T 43.8A 57.5AB 48.5A 31.5A 3T 39.0A 44.3A 47.8A 49.3A 3T 43.3A 62.8A 47.0A 32.0A 0T 34.5A 44.5A 50.8A 42.7B 0T 41.5A 57.8AB 46.0A 29.5A MSD 6.4 3.1 11.3 2.4 MSD 2.4 5.3 3.7 8.2

MSD=meansignificantdifference;n.a.=notapplicable.

AsatBurmerange,thenumberoffungicidespraysdidnotappear

tohavemucheffectonZSVvalue.

4. Discussion

Foliarfungicidesinfarmingsystems,includingwheatcrop,are

typicallyusedtopreventeconomiclossesfromimportantcrop

dis-eases.Theiruseisalsoguidedbytheprofitthatcanbemadeon

themarketablevalueoftheextraquantityandqualityofgrains.

Forinstance,theextensionofthedurationofgreen leafareaof

thethreeupper leavesthroughtheapplication ofcertain foliar

fungicidesmaysubstantiallyincreasethegrainfillingperiodand

finalyields(Goodingetal.,2000;DimmockandGooding,2002b;

Pepleretal., 2005), whichin turnmayleadtoincreased finan-cialreturns(dependingontheproportionofyieldgain andthe wheatmarketprice).Althoughgenotype-dependent,grainquality inwheatisinfluencedbyenvironmentalfactorsandmanagement practices(Kelley,2001;Wangetal.,2004;Hasnizaetal.,2013). Inourstudy,theeffectsofthreefungicidesprayregimes(1T–3T) onfourdifferentgrainqualityparameters(i.e.,TGW,TW,GPCand ZSV)wereassessedovera 4-yearperiodattwositesin Luxem-bourg.Thetimeofapplicationandthedecisiontoapplyornotthe 1TwasrecommendedbytheDSSPROCULTUREandadd-ons.The resultsindicatethatallfungicidetreatmentsensuredtheprotection ofwheatcultivarsagainstthemainfungaldiseasesandimproved cropdevelopment.LowerseveritiesofSLB,WLRandWPMwere observedonplantsintreated plotsduringthegrowingseasons comparedtoplantsincontrolplots andresultedinhigherfinal grainyieldsrecordedintreatedplotsinmostcases.

LowerTWvalueswerefoundatBurmerangein2007(Fig.3). Thiscouldberelatedtotheseverityoffoliardiseases,namelySLB (Blandinoetal.,2009).However,thecontrastingbehaviorofTW duringthissevereepidemicsyearofSLB(2007)atEverlange(any

significantdropfrom2006to2007comparedtoBurmerange;Fig.4) suggeststhatotherfactorssuchasenvironmentalconditionsor interactionsbetweenenvironmentandgenotypemightplayarole inthisvariability(Khaliletal.,2002).AsFHBplaysaroleinTW (Salgado etal.,2015),anotherpossiblereasonforthelowerTW valuesinBurmerangein2007canbeattributedtotheextremely highlevelofFHBdetectedinthatyearinthecountry.Inaddition, Burmerangewasthelocationwiththehighestaverageseverityof infectedspikeletsperheadfoundinthecountry.Indeedthe rela-tionshipamongFHB,fungicidetreatmentsandgrainqualitywould deserveaspecificstudytobetterunderstandtherolethat fungi-cidetreatmentshaveonmycotoxinaccumulation(Giraudetal., 2011).Outofthe8differentexperimentsinthisstudy,fungicide applicationfailedtohaveaneffectonTWin7cases(theonly excep-tionbeing2006atBurmerange).AlthoughKelley(2001)andWang etal.(2004)reportedapositiveeffectoffoliarfungicideonTW inwheat,thediscrepancyinresponseofTWtofungicidemight beexplainedbydependenceontheinteractionsofdisease sever-ity,cultivarresistanceandenvironmentalconditions(Kelley,2001). Forinstance,Rodrigoetal.(2015)reportednosignificanteffectof fungicidesonTWinwinterwheatunderMediterraneanconditions, whichoftenhavedrierconditionsthroughoutthegrowingseason. AsignificanteffectoffungicidesonTGWwasobservedinmost seasonsatBurmerange(3outof4years)andin50%ofseasonsat Everlange,withnosignificantdifferencebetweentreatedplotsat eithersite(with2008beingexceptionalatbothsiteintermsoflow tonegligiblefungaldiseaseincidence,norecommendationofthe 1TtreatmentfromtheDSS,variabilityinthefungicideresponse intermsofgrainquality,andoccurrenceoflodging).These find-ingsconcurwiththeconclusionsofpreviousstudies(e.g.,Gooding etal.,2000;Ruskeetal.,2003,2004).Indeed,theseauthorshave reportedthattheuseofstrobilurinandtriazolefungicides consis-tentlyincreasedTGWandgrainyield,namelybecauseofthedelay

ofsenescenceoftheflagleaves.Inourexperiment,thefungicides usedincludedamixtureofstrobilurinandtriazolesinmostcases (Table4).Suchdelaysinthesenescenceprocesshavebeenreported inpreviousstudiesfortheseexperimentalsites(ElJarroudietal., 2012a;Kouadioetal.,2012),withthegreatestdelaysonthoseplots receivingthe3Ttreatment.However,thesimilarityofTGWforall fungicidetreatedplotsin5outofthe8experimentsshowedthat neitherthenumberoffungicidesprayingnorthedosesor formu-lationofthemixtureshadamajorimpactonthisqualityvariable. TheGPCwasgenerallynotaffectedbyfungicideapplicationsat Everlange(therewasnocleartrendfoundatBurmerange), sup-portingtheconclusionsofpreviousstudies(e.g.,Ruskeetal.,2003, 2004;BlandinoandReyneri,2009).Ruskeetal.(2004)reported animprovementofflourproteinconcentrationafteranadditional 40kgNha−1 application atflagleafemergencein winterwheat (cultivarMalacca)inUnitedKingdom.Inourstudydifferentratesof nitrogenwereappliedateachsite(Table1),yettheaimwasnotto investigatesucheffectsongrainqualityparameters.Asdiscussed byBlandinoetal.(2009),variouseffectsandinteractions,including thesenescenceprocessduringgrainfillingandthetranslocationof carbohydratestograin,thelengthofthephotosyntheticperiod,and thefoliardiseasestargetedandfungicidesusedfortheircontrol, canimpactGPCinwheateitherpositivelyornegatively.Devising eachoftheseeffectsandinteractionswasbeyondtheaimofthis study.Nevertheless,weassumedthattheseeffectsalsoinfluenced theGPCduringourexperiments.

Overall,theassessmentoftheimpactofthenumberof fungi-cidespraysonfourwheatgrainqualityparametersduringa4-year periodrevealsthatfungicideseitherdidnotaffectTWandZSV,or hadaslighteffect,suggestedbylackofaneffectin≥75%.A sig-nificantpositiveeffectwasobservedonTGWatbothsitesinall years,except2008and2008–2009atBurmerangeandEverlange, respectively.Whereas,nodistincteffectwasrecordedforGPCat Burmerange,andnosignificanteffectatEverlange,exceptin2006. Whenasignificanteffectoffungicidetreatmentswasobserved,the ANOVAshowedthatthedifferencewasnotsignificantamongthe fungicidetreatedplots(i.e.,differenceswerebetweenthefungicide treatedandnon-treatedplots).Thusasinglefungicidetreatment resultedingrainwiththesamequalitycomparedwithgrainfrom thoseplantsreceivingthedoubleortripletreatments.Thisstudy tiesinvaluable,complementaryinformationregardingan assess-mentoftheimpactofthenumberoffungicidesprayingsonwheat grain quality in Luxembourg. Indeed, El Jarroudi et al. (2015) pointedoutthatasinglefungicidetreatmentledtograinyieldgain andfinancialreturnssimilartothosefromadoubleoratriple fungi-cidetreatment.Regardingthequalityparametersanalysedhere, thesingletreatmentalsoresultedinsimilargrainquality com-paredwithadoubleortripletreatment.Inconclusion,equivalent yieldoutputscanbeachievedwithsuchasinglefungicide treat-ment,ifitisappropriatelytimed.However,theresultsofthegrain qualityassessmentareinevitablyconstrainedbytheexperimental conditionsthatprevailed(e.g.,wheatcultivarsused,weather, fun-galdiseases,severityofepidemics,etc.).Furtherresearchinvolving larger,multiyear,multilocationexperimentswiththemajorwheat cultivarsiswarrantedtoextendtheresultsacrossabroaderrange ofcircumstances;furtherworkwillhelpoptimisefungicideusein winterwheatinEuropeandelsewhere.

Acknowledgments

ThisresearchwasfundedbytheMinistryofHigherEducation andResearchoftheGrand-DuchyofLuxembourgandthe Admin-istrationdesServicesTechniquesdel’Agriculture(ASTA)through theMACRYproject.WearegratefultotheASTAandthe Obser-vatoryforClimateandEnvironmentoftheLuxembourgInstitute

ofScienceandTechnologyforprovidingmeteorologicaldata.We alsothankFrédéricGiraud,CarineVrancken,AbdeslamMahtour, ChristopheMackels,VirginieSchyns,FriederikePogoda,Guy Mir-gain,MarcKailsandAlexandreNuttensfortheirtechnicalsupport. AlllaboratoryanalyseswereperformedbythelaboratoryVERSIS FarmSupport(formerAgriConsult),Mersch,Grand-Duchyof Lux-embourg.

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