J[ Agronomy + Crop Science 074\ 042*051 "1999#Þ 1999 Blackwell Wissenschafts!Verlag\ BerlinISSN 9820!1149

Institute of Crop Science and Plant Breedin`\ Christian!Albrechts!University of Kiel\ Kiel\ Germany

Effects of Fungicide on Grain Yield of Barley Grown in Different Cropping

Systems

J[ P[ Yang\ K[ Sieling and H[ Hanus

Authors| addresses] Dr J[ P[ Yang\ Agro!Ecology Institute of Zhejiang Agricultural University\ Hangzhou\ 209918\ China^ Dr

K[ Sieling "corresponding author# and Prof[ Dr H[ Hanus\ Institute of Crop Science and Plant Breeding\ Christian!Albrechts!

University of Kiel\ Olshausenstr[ 39\ D!13007 Kiel\ Germany

With 0 _gure and 7 tables

Received July 16\ 0888^ accepted December 3\ 0888

Abstract

The e}ect of fungicides and their combination on yieldof barley under di}erent nitrogen\ slurry and tillage treat!ments was investigated at Hohenschulen ExperimentalStation near Kiel\ Germany in 0880Ð86[ Various fungi!cide treatments "no fungicide\ and treatment with stem\leaf and ear fungicides and combinations of these#\ twonitrogen levels "019 and 139 kg N ha−0#\ two tillage sys!tems "minimum and conventional tillage# and four slurryapplications "no application\ and autumn\ spring andautumn plus spring applications# were used[ On average\fungicide application increased barley yield by 0[0 t ha−0[The fungicide treatments could be classi_ed into fourtypes] "0# fungicides against stem diseases\ which slightlyincreased yield by 9[14 t ha−0\ very similar to the resultsfor the untreated control^ "1# leaf fungicides and earfungicides applied separately\ and fungicides against acombination of stem and leaf diseases\ which increasedyield by 0[9 t ha−0 on average^ "2# fungicides against acombination of ear and stem diseases\ which increasedthe yield by 0[11 t ha−0\ and "3# fungicides against acombination of leaf and ear diseases and a combinationof stem\ leaf and ear diseases\ which increased yield by0[48 t ha−0 on average[ The e}ects of fungicide on theyield were modi_ed by crop husbandry[ It can be con!cluded that application of fungicides against a com!bination of leaf and ear diseases could increase barleyyield and reduce yield variation[

Key words] barley * fungicide application * nitro!gen * slurry application * tillage * yield

Introduction

The application of fungicides is an important wayto increase cereal crop yield "Kundler et al[ 0877\Minton 0889\ Sieling et al[ 0886#[ However\ theresults produced by di}erent types of fungicide anddi}erent application doses depend on the weather\soil and management conditions[ Dennert andFischbeck|s "0880# experimental results in Germany

U[S[ Copyright Clearance Center Code Statement] 9820Ð1149:1999:7492Ð9042 ,04[99:9

indicated that the application of fungicides againststem base diseases was not economic for winterwheat sown at a low seeding rate on the optimumdate "thin sowing#[ Other authors have stated thatfungicide application increased yield in most situ!ations\ even without observable disease problems[Jordan "0881# found that mixing of fungicide withdi}erent active substances gave the best overall con!trol of disease[ Disease control and the yieldresponse of barley were greatest when fungicideswere applied during a 2!week period after the mainnitrogen application in April[ No additional yieldbene_ts were obtained by carrying out two fungicideapplications "Jordan et al[ 0878#[ Hanus and Schoop"0876# showed that the application of fungicides alsoincreased the wheat and barley yield potential\ butthe yield variability over the treatments remainedthe same\ except for the high N application rate of×199 kg ha−0[ Bacon and Wells "0880# found thatthe e}ect of wheat variety and nitrogen rate onthe wheat yield varied with site and year\ while anitrogen application rate of over 001 kg ha−0 did notgenerally increase yield without fungicide treatment[Prew et al[ "0875# showed that the rotation had thelargest e}ect on the winter wheat yield[ The appli!cation of fungicides temporarily decreased the inci!dence of some strains of micro~ora on the ears ofwheat\ especially in wheat after barley comparedwith wheat after oats[ Spring or summer sprayingof fungicides gave the same average yield increase\mainly due to larger grain size[ The e}ects weregreater with earlier sowing and larger amounts of N"Prew et al[ 0874#[

The objective of this work was to clarify the e}ectof fungicide treatments "fungicides against stem\ leafand ear diseases\ and combinations of these# underdi}erent _eld management conditions "tillage\ nitro!

043 Yang et al[

gen and slurry application# on the grain yield ofbarley in a long!term experiment[

Materials and Methods

The experimental results presented here are part of theCollaborative Research Centre SFB 081 project "Opti!mization of Cropping Systems with regard to Pro!ductivity and Ecological E}ects# which was establishedin autumn 0889 on a pseudogleyic sandy loam at theHohenschulen Experimental Farm of the University ofKiel\ North!west Germany[

Treatments and design

The _eld experiment was conducted in 0880Ð86 and basedon an oilseed rape "cv[ Falcon#Ðwinter wheat "cv[Orestis#Ðwinter barley "cv[ Alpaca# rotation[ The exper!imental design was a single!replicate split!split!plotdesign with the two tillage treatments as the main plotsand the four slurry application treatments as the subplot[Mineral nitrogen fertilizer and fungicide treatments wereapplied in the subsubplots[ All the factors and factorlevels are shown in Table 0[

In year 0 of the experimental treatment\ each of thethree crops "oilseed rape\ wheat and barley# of therotation were grown separately on three main plots[ Eachmain plot was then used for a complete rotation of threecrops\ with the rotation on each main plot beginning atthe point in the rotation cycle corresponding to the initialmain plot crop[ Each crop was grown in each year andeach main plot _nished a full rotation after the 2 years ofthe experiments[ The same treatment regimes wereapplied to the same subplots and the same subsubplots ineach year\ so that the cumulative e}ects of each treatmentwere balanced both for year and for crop[

Nitrogen "in the form of calcium ammonium nitratewith 16) N# was applied at the beginning of springgrowth\ stem elongation and ear emergence of barley[Pig slurry was applied in autumn on the stubble of thepreceding crop and ploughed into the soil[ Spring appli!cation of slurry was carried out in April when soil andweather conditions were suitable[

Fungicides were used at three times in spring "Table 1#[Other crop management activities followed standardfarming practices[ The plot size was 01×2m1\ of whichan area of 8m1 was harvested by combine[ Yield wasstandardized to t ha−0 total dry matter based on themoisture content of grain sampled[ The statistical analy!sis of the results was performed using SAS software "SAS:STATTM Guide for Personal Computers Version 5\ 0876#[

Results

Fungicide effects on grain yield

The grain yield of barley and the e}ects of fungicideon grain yield showed signi_cant year!by!year vari!ation "Table 2#[ The highest yield was obtained in0883 in the F7 treatment[ The maximum yield

di}erence between the untreated control "F0# andthe best fungicide treatment was 2[03 t ha−0 in 0882\and the minimum di}erence was 9[88 t ha−0 in 0885[On a 6!year average\ barley yielded 4[41 t ha−0 with!out fungicides and 6[03 t ha−0 in the F6 treatment\where leaf and ear pathogens were controlled[ Com!pared to the untreated control\ fungicides againststem diseases "S#\ against leaf pathogens "L# andagainst ear diseases "E# increased yield by 9[14\ 9[82and 0[93 t ha−0\ respectively[ The combination offungicides against stem and leaf\ stem and ear\ andleaf and ear diseases increased the yield by 0[92\ 0[11and 0[51 t ha−0\ respectively[ The highest yield wasobtained when fungicides against leaf and ear dis!eases "F6# were applied[

The main e}ects of di}erent fungicides on theyield of barley as compared to F0 were di}erent"Table 3#[ Application of one fungicide "S\ L or E#had a positive e}ect on the yield\ that against eardiseases being the most e}ective[ When two or threefungicides were combined\ the e}ects of the inter!actions S × L\ S × E\ L × E and S × L × E werefound to be negative[ Increasing the fungicide appli!cation dose decreased the e.ciency and producednegative interaction e}ects between the di}erentfungicide types[

On the basis of the reaction of the barley yield\fungicide treatments could be classi_ed into fourcategories "Table 2#[0 Treatment with fungicide against stem diseases"F1#\ which gave a yield that was almost the sameas that of the untreated control "F0# in _ve out ofseven years "the exceptions being 0885 and 0886#[The yield increase was 9[14 t ha−0 on average[1 Treatment with fungicide either against diseaseson the leaves "F2# or against diseases on the ears"F3#\ and treatment with a combination of stem andleaf fungicides "F4#\ which resulted in the same yieldincrease of about 0[9 t ha−0 on average[2 Treatment with fungicides against stem and eardiseases in combination "F5#\ which gave a yieldincrease of 0[11 t ha−0[3 Treatment with fungicides against leaf and eardiseases in combination and treatment with all threefungicides\ which gave to the largest yield responsein all seven years[

Interaction between fungicide treatments andcropping management measures

Field management and its interaction with fungicidetreatment can also a}ect the yield of barley[ Thenitrogen!by!fungicide interaction was signi_cant

044Fungicide E}ects on Barley Yield

Table 0] Factors and factor levels in the experimental _eld of Hohenschulen farm[ "a# Soil tillage"main plot#^ "b# application of pig slurry "subplot#^ "c# amount and timing of mineral N fertilizerapplication "kg N ha−0#^ "d# fungicide application

"a#

T0 Minimum tillage technique without ploughingT1 Conventional system with ploughing followed by a harrowÐdrilling combination

"b#

S0 NoneS1 In autumn "target] 79 kgNha−0#S2 In spring "target] 79 kgNha−0#S3 In autumn and in spring "0880 only in late spring# "target] 79¦79 kg N ha−0#

"c#

Beginning of Beginning of Eargrowth in spring stem elongation emergence Total N

N019 39 39 39 019N139 79 79 79 139

"d#

Fungicides against]

stem pathogens leaf pathogens ear pathogens

F0 − − −F1 "S# ¦ − −F2 "L# − ¦ −F3 "E# − − ¦F4 "S¦L# ¦ ¦ −F5 "S¦E# ¦ − ¦F6 "L¦E# − ¦ ¦F7 "S¦L¦E# ¦ ¦ ¦

S�stem^ L� leaf^ E�ear[

"Table 4#[ Compared to the control "F0#\ applicationof fungicides increased the barley yield by 9[82 tha−0 in the 019 kg N ha−0 treatment and by 0[15 tha−0 in the 139 kg N ha−0 treatment "Table 5#[ Theapplication of a single fungicide was more e}ectiveat lower N input than at higher N input[ When139 kg N ha−0 was applied\ two or more fungicidesagainst stem\ leaf and ear diseases gave a greaterincrease in the barley yield[ For the di}erent targettypes "stem\ leaf and ear diseases# at 019 kg N ha−0

input\ the application of a single fungicide and com!binations of two and all three fungicides increasedyield by 9[50\ 0[03 and 0[14 t ha−0\ respectively\ com!pared with F0[ At 139 kg N ha−0\ the yield increaseswere 9[75\ 0[30 and 0[89 t ha−0\ respectively[

In contrast to mineral fertilization\ application ofslurry with di}erent fungicides showed no sig!ni_cant interaction e}ect on the barley yield"Table 4#[ In general\ application of fungicidesincreased the yield in all slurry treatments "Table 6#[The fungicide e}ects on the yield were stronger thanthe slurry e}ects on the yield in the same fungicidetreatments[ The barley yield with fungicide treat!ment was 9[85 t ha−0 higher than the yield withoutslurry and fungicide "MA to F0#[ With fungicideapplications\ yield increased by 9[86\ 0[21 and 9[86 tha−0\ respectively\ as compared to treatment with!out fungicides[ Fungicides gave a greater increase inthe yield in the spring slurry treatment[ For thefungicide treatments\ the application of single fungi!

045 Yang et al[

Table 1] Fungicide applications during the _eld experiments "0880Ð86#

Date Commercial name Active substance"s# Amount "kg ha−0#

04[93[0880 Sportak "for stem# Prochloraz 0[196[94[0880 Simbo "for leaf# Fenpropimorph ¦ Propiconazol 0[995[95[0880 Folicur "for ear# Tebuconazol 0[998[93[0881 Sportak "for stem# Prochloraz 0[195[94[0881 Simbo "for leaf# Fenpropimorph ¦ Propiconazol 0[911[94[0881 Folicur "for ear# Tebuconazol 0[904[93[0882 Sportak "for stem# Prochloraz 0[101[94[0882 Simbo "for leaf# Fenpropimorph ¦ Propiconazol 0[913[94[0882 Folicur "for ear# Tebuconazol 0[918[93[0883 Sportak "for stem# Prochloraz 0[198[94[0883 Simbo "for leaf# Fenpropimorph ¦ Propiconazol 0[913[94[0883 Folicur "for ear# Tebuconazol 0[915[93[0884 Sportak "for stem# Prochloraz 0[995[94[0884 Simbo "for leaf# Fenpropimorph ¦ Propiconazol 0[915[94[0884 Folicur "for ear# Tebuconazol 0[995[94[0885 Sportak "for stem# Prochloraz 0[902[94[0885 Opus Top "for leaf# Epoxiconazol ¦ Fenpropimorph 0[994[95[0885 Folicur "for ear# Tebuconazol 0[997[94[0886 Sportak "for stem# Prochloraz 0[9

Opus Top "for leaf# Epoxiconazol ¦ Fenpropimorph 0[929[94[0886 Opus Top "for ear# Epoxiconazol ¦ Fenpropimorph 0[9

0 Hoechst Schering AgrEvo GmbH\ Frankfurt\ Germany[1 Novartis Agro GmbH\ Frankfurt\ Germany[2 Bayer Vital GmbH + Co[ KG\ Leverkusen\ Germany3 BASF Akbengesellschaft\ Limburgerhof\ Germany[

Table 2] E}ects of fungicides on the grain yield of barley "t ha−0# in 0880Ð86

Year

Treatment 0880 0881 0882 0883 0884 0885 0886 Mean

F0 4[49d 4[13c 2[39d 5[16c 4[88c 5[44d 4[57b 4[41e

F1 4[30d 4[39c 2[40d 5[32c 5[17c 6[07bc 5[06a 4[66d

F2 5[08c 5[01b 3[63c 6[97b 6[94b 6[35abc 5[42a 5[34c

F3 5[70b 5[10b 4[05bc 6[13b 5[84b 6[91c 5[44a 5[45c

F4 5[12c 5[00b 4[44b 6[18b 6[08ab 6[16abc 5[07a 5[44c

F5 5[64b 5[26b 4[52b 6[27b 6[25ab 6[31abc 5[42a 5[63b

F6 6[13a 5[60a 5[32a 6[55a 6[40a 6[58a 5[61a 6[03a

F7 6[25a 5[60a 5[43a 6[63a 6[18ab 6[43ab 5[32a 6[98a

Mean 5[46 5[12 4[26 6[15 6[98 6[26 5[34 5[51

Yield values followed by the same letter do not di}er at P¾ 9[94[

cides increased the yield by 9[51\ 9[83 and 9[68 tha−0\ that of two fungicides by 0[03\ 0[46 and 0[22 tha−0 and that of three fungicides by 0[36\ 0[64 and0[53 t ha−0 in the autumn slurry\ spring slurry andautumn plus spring slurry treatments\ respectively[

The application of fungicides against leaf and eardiseases produced the highest average yield in allslurry treatments except for the autumn slurry[

The maximum yield di}erence was on average0[80 t ha−0 in the spring slurry treatment for fungi!

046Fungicide E}ects on Barley Yield

Table 3] Contribution "t ha−0# of the di}erent fungicides and their interactions to yield di}erences

Yield Yield di}erence Contribution of the di}erent fungicidesTreatment "t ha−0# "t ha−0# and their interactions "t ha−0#

F0 4[41 * *F1 "S# 4[66 ¦9[14 S�¦9[14F2 "L# 5[34 ¦9[82 L�¦9[82F3 "E# 5[45 ¦0[93 E�¦0[93F4 "S¦ l# 5[44 ¦0[92 S×L�−9[04F5 "S¦E# 5[63 ¦0[11 S×E�−9[96F6 "L¦E# 6[03 ¦0[51 L×E�−9[24F7 "S¦ l¦E# 6[98 ¦0[46 S×L×E�−9[98

S�stem^ L� leaf^ E�ear[

Table 4] Analysis of variance for fungicide e}ects on the grain yield of barley as modi_ed bydi}erent crop husbandry treatments "tillage\ slurry and nitrogen# in 0880Ð86

Application of]

one fungicide two fungicides three fungicidesSource "S\ L or E# "S¦L\ S¦E or L¦E# "S¦L¦E#

Tillage ns ns nsSlurry ns ns nsNitrogen � � ��Year ns �� ��Tillage×Slurry ns ns nsTillage×Nitrogen ns ns nsSlurry×Nitrogen ns ns nsYear×Tillage ns ns nsYear×Slurry ns ns nsYear×Nitrogen ns � ns

S�stem^ L� leaf^ E�ear[ns�no signi_cant di}erence^ �\ �� signi_cant at the 9[94 and 9[90 probability levels\ respectively[

cides against leaf and ear diseases in combination"F6 compared to F0#[ The yield increases due tothe di}erent fungicide combinations were 9[59 "onefungicide^ average for S\ L\ E#\ 0[06 "two fungicides^average for S ¦ L\ S ¦ E\ L ¦ E# and 0[33 t ha−0

"three fungicides^ S ¦ L ¦ E# in the treatment with!out slurry\ and 9[83\ 0[46 and 0[64 t ha−0\ respec!tively\ in the spring slurry treatment[ Althoughfungicide application led to higher yields\ thee.ciency decreased as the number of fungicides usedincreased] average e.ciencies were 9[59\ 9[46 and9[16 t ha−0 without slurry and 9[83\ 9[52 and 9[07 tha−0 with spring slurry for the one!fungicide\ two!fungicide and three!fungicide combinations\ respec!

tively[ The most e}ective way to control disease andto obtain a higher yield seemed to be to apply acombination of fungicides against leaf and ear dis!eases "Table 5#[ Spring slurry increased the yield ofbarley in almost all fungicide treatments\ except inthe treatment without fungicides\ and gave the high!est values[

In general\ there were no di}erences in the e}ecton barley yield of di}erent fungicide treatments incombination with minimum or conventional tillage[There were no signi_cant interaction e}ects on theyield "Table 4#[ With the application of fungicides\the yield within tillage treatments also increased"Table 7#[ The fungicides increased barley yield by

047 Yang et al[

Table 5] E}ect of fungicide by mineral N fertilization interaction "t ha−0# on the grain yield of barley "0880Ð86#

Fungicide treatment

F0 F1 "S# F2 "L# F3 "E# F4 "S¦L# F5 "S¦E# F6 "L¦E# F7 "S¦L¦E# MA0

YieldN019 4[61 4[83 5[40 5[42 5[63 5[66 6[98 5[86 5[54N139 4[21 4[59 5[28 5[48 5[23 5[65 6[07 6[11 5[47Increase1

N019 * 9[11 9[68 9[70 0[91 0[94 0[26 0[14 9[82N139 * 9[17 0[96 0[13 0[91 0[33 0[65 0[89 0[15

LSD9[94 for Nitrogen�9[952[LSD9[94 for Fungicide�9[149[LSD9[94 for Nitrogen×Fungicide�9[490[S�stem^ L� leaf^ E�ear[0 MA�mean of all fungicide treatments "from F1 to F7#[1 Increase compared to F0[

Table 6] E}ect of fungicide by slurry interaction "t ha−0# on the grain yield of barley "0880Ð86#

Fungicide treatment

F0 F1 "S# F2 "L# F3 "E# F4 "S¦L# F5 "S¦E# F6 "L¦E# F7 "S¦L¦E# MA0

YieldS0 4[32 4[43 5[04 5[30 5[32 5[45 5[71 5[76 5[28S1 4[58 4[76 5[40 5[46 5[52 5[71 6[96 6[05 5[55S2 4[34 4[74 5[58 5[51 5[69 6[90 6[25 6[19 5[66S3 4[40 4[70 5[35 5[54 5[40 5[60 6[20 6[04 5[54Increase1

S0 * 9[00 9[61 9[87 0[99 0[02 0[28 0[33 9[85S1 * 9[07 9[71 9[77 9[83 0[02 0[27 0[36 9[86S2 * 9[39 0[13 0[06 0[14 0[45 0[80 0[64 0[21S3 * 9[29 9[84 0[03 0[99 0[10 0[79 0[53 9[86

LSD9[94 for Slurry�9[014[LSD9[94 for Fungicide�9[149[LSD9[94 for Slurry×Fungicide�0[999[S�stem^ L� leaf^ E�ear[0 MA�mean of all fungicide treatments "from F1 to F7#[1 Increase compared to F0[

9[88 t ha−0 for minimum tillage and by 0[11 t ha−0

for conventional tillage as compared to plots with!out fungicides[ Compared to the F0\ the applicationof single fungicides produced a yield increase of9[54 t ha−0\ the combination of two fungicides anincrease of 0[05 t ha−0 and all three fungicides anincrease of 0[49 t ha−0 under minimum tillage and9[73\ 0[32 and 0[53 t ha−0\ respectively\ under con!ventional tillage[ When the e}ects on the yield of

treatment with di}erent fungicides "fungicidesagainst stem\ leaf and ear diseases and their com!binations# were considered\ higher yields were foundto be obtained with the fungicide against ear diseasesand with the combination of the fungicides againstleaf and ear diseases[ The increase in the yield withfungicides was greater after conventional tillagethan after minimum tillage[ However\ the e.ciencyof the increase of the yield decreased as the number

048Fungicide E}ects on Barley Yield

Table 7] E}ect of fungicide by tillage interaction "t ha−0# on the grain yield of barley "0880Ð86#

Fungicide treatment

F0 F1 "S# F2 "L# F3 "E# F4 "S¦L# F5 "S¦E# F6 "L¦E# F7 "S¦L¦E# MA0

YieldT0 4[60 4[74 5[37 5[64 5[54 5[74 6[02 6[10 5[69T1 4[22 4[58 5[32 5[27 5[35 5[57 6[03 5[86 5[42Increase1

T0 * 9[03 9[66 0[93 9[83 0[03 0[31 0[49 9[88T1 * 9[25 0[09 0[94 0[02 0[24 0[70 0[53 0[11

LSD9[94 for Tillage�9[951[LSD9[94 for Fungicide�9[149[LSD9[94 for Tillage×Fungicide�9[490[S�stem^ L� leaf^ E�ear[0 MA�mean of all fungicide treatments "from F1 to F7#[1 Increase compared to F0[

of fungicides used increased] average e.ciencieswere 9[54\ 9[40 and 9[23 t ha−0 under minimum till!age and 9[73\ 9[48 and 9[10 t ha−0 under con!ventional tillage[

Effects on the variation of grain yield

The standard deviation "S[D[# of barley yield variedgreatly with the combination of fungicides againststem and leaf diseases at a high rate of N application\with slurry "autumn\ spring and autumn plus spring#and minimum tillage "Fig[ 0#[ There was little S[D[variation for the combination of fungicides againststem and leaf diseases in the treatment with 019 kgN ha−0\ without slurry and conventional tillage[ Ata high N input level\ the S[D[ of the barley yieldshowed relatively little variation for application ofa single fungicide\ but increased in the fungicidecombinations[ There was also little variation in S[D[at lower N input levels with application of singlefungicides\ but variation increased with com!binations of two or three fungicides[ The e}ect offungicide on the S[D[ with slurry was stable for theapplication of a single fungicide\ then increased withthe stem and leaf fungicide combination anddecreased afterwards[ The S[D[ for the minimumtillage treatment with fungicides also showed similartrends\ but conventional tillage indicated almost thesame variation[

Discussion and Conclusion

Fungicides increased the yield of barley at Kiel inall seven years[ The yield increase varied with the

di}erent fungicide applications under di}erent min!eral N\ slurry and tillage management conditions[The interaction e}ect of fertilization and fungicideapplication on the yield was positive\ which is inagreement with results of Springer and Heitefuss"0877#[

In our experiment\ we found a signi_cant year!by!fungicide interaction e}ect on the barley yield"Table 4#\ which indicates that the climatic variationover the 6 years was an important factor in fungaldisease development and hence in the e}ects offungicide on yield[ If two or three fungicides wereapplied\ negative interactions between the splittingsoccurred\ presumably as a result of similar controlmechanisms[ The single fungicide produced higherbarley yields at lower N\ while the two! and three!fungicide combinations produced higher yields atthe higher N application rate[ At higher N\ fungaldiseases could be an important limiting factor onyield increase\ so more fungicides should perhaps beapplied to reduce the risk of yield losses[ This resultis similar to the results obtained by Jordan et al["0878#[ In addition\ the timing of nitrogen dressingshad a signi_cant e}ect on the progress of stem baseand foliar diseases "Clare et al[ 0889#[ The severityof the diseases increased with the N rate "Howardet al[ 0883#\ and this might be the reason why higherN input required a higher fungicide dose to controlthe diseases[ In our experiments\ the combinationof fungicides against leaf and ear diseases producedthe highest yield in almost all conditions[ We alsofound that mineral N fertilization showed a sig!ni_cant interaction with fungicide treatment in its

059 Yang et al[

Fig[ 0] E}ect on the standard deviation "S[D[# of barley yieldof treatment with di}erent combinations of fungicide underdi}erent nitrogen "a#\ slurry "b#\ and tillage management "c#conditions

e}ect on barley yield within years[ The year!by!mineral N interaction for the combination of twofungicides had an especially signi_cant e}ect on bar!ley yield "Table 4#[ The climatic conditions and N

management system greatly a}ected disease devel!opment and infection\ and also _nal yield losses[Fungicide applications had a signi_cantly greatere}ect on barley yield at higher N application rates\as the severity of disease increased with increasingrate of N application\ especially when fungicideswere not applied[ However\ for the slurry treat!ments\ the situation was di}erent[ As the number offungicides used increased\ autumn plus spring slurrydid not give the same results as were found at thehigher mineral N level[ The spring slurry applicationwith the combination of two fungicides gave thebest e}ect on barley yield\ presumably due to thelower and slower N "re!#mineralization from theautumn slurry and the lower slurry N!use e.ciency"Sieling et al[ 0886\ 0887#[ In addition\ the climaticand soil conditions may retard protein synthesis andproduce excessive accumulation of soluble aminoacids which encourages fungal growth\ making thebarley more susceptible to diseases "Conry andDunne 0882#[ Therefore\ a more intensive fungicidetreatment was better at controlling disease and gavea greater yield increase under spring slurryconditions[

Tillage only slightly modi_ed the e}ect of thefungicides on yield variation[ There were no sig!ni_cant di}erences between the minimum and con!ventional tillage systems[ Sturz and Carter "0884#indicated that disease levels of barley were not sig!ni_cantly in~uenced by soil source and tillageregime[ Some authors have reported that no!tillageand minimum!tilled barley and wheat sustained gre!ater damage from root disease than did con!ventional!tilled barley and wheat\ because the resi!due remaining on the ground and under the groundcould be a source of fungal transfer to the followingcrop "Smiley and Wilkins 0882\ Wildermuth et al[0886#[ In this experiment\ we did not _nd similarresults\ which could be due to the low winter tem!perature at Kiel[ Other authors have also foundthat wheat yields were not signi_cantly a}ected bytillage!related foliar disease "Stover et al[ 0885#[Therefore\ in this experiment\ the separate appli!cations of fungicides against leaf and ear diseasesproduced similar yields for minimum and con!ventional tillage\ and their combination gave higheryields in the two tillage systems[

The S[D[ values in di}erent cropping systemsindicated that\ under higher N\ spring slurry andminimum tillage conditions\ disease was a severelimiting factor on yield potential\ presumablybecause the large N input changed the susceptibilityof the plants[ The application of a combination of

050Fungicide E}ects on Barley Yield

fungicides against stem and leaf diseases\ which canonly control the disease at the vegetative stage\resulted in higher S[D[ within years\ but disease atthe reproductive stage can sometimes reduce theyield sharply in speci_c years\ resulting in a higherS[D[ With the combination of fungicides against leafand ear or stem and ear diseases or the combinationof all three fungicides\ the yield was stable withlower yield variation[

From this 6!year experiment on the impact offungicides on barley yield\ it can be concluded thatthe application of fungicides was e}ective under allconditions studied\ especially under higher N input[Fungicides and their combinations should beapplied to reduce yield losses and yield variationwith high mineral N and spring slurry applications[The combination of two fungicides was optimal forcontrolling diseases and increasing yield[ There wasno signi_cant di}erence in disease severity betweenthe tillage systems\ so the impact of fungicide treat!ment on the yield did not di}er between these twotillage treatments[

Zusammenfassung

Ein~u) von verschiedenen Fungizidstrategien auf denErtrag von Wintergerste in unterschiedlichenProduktionssystemen

Die Wirkung von Fungiziden und ihre Kombination aufden Ertrag von Gerste in unterschiedlichen Produktions!systemen wurde in den Jahren 0880Ð86 im Rahmen einesFeldversuches auf dem Universita�tsversuchsgut Hohen!schulen der Christian!Albrechts!Universita�t zu Kiel"Deutschland# untersucht[ Neben der unbehandeltenKontrolle wurden sieben weitere Fungizidvarianten"Fungizide gegen Halmbasis!\ Blatt! und AÝhrenkrankhei!ten sowie deren Kombinationen# bei zwei Bodenbearbei!tungsvarianten "Fra�ssohlensaat\ P~ugdrillsaat#\ vier Gu�l!levarianten "keine Gu�lle\ 79 kg N ha−0 in Form vonSchweinegu� lle im Herbst\ im Fru�hjahr sowie im Herbstplus im Fru�hjahr# und 1 mineralischen N!Stufen"39:39:39 und 79:79:79 kg N ha−0# gepru�ft[ Im Mittel deru�brigen Varianten steigerten die Fungizidbehandlungendie Gerstenertra�ge um durchschnittlich 0\0 t ha−0[ IhrerWirkung entsprechend ko�nnen die Fungizide in vierArten eingeteilt werden] "0# Fungizide gegen Halmba!siserkrankungen erho�hten die Ertra�ge im Vergleich zurunbehandelten Kontrolle nur leicht um etwa 9\14 t ha−0["1# Fungizide gegen Blatt!\ AÝhrenkrankheiten bzw[ dieKombination von Halmbasis!¦Blattbehandlungenfu�hrten zu Ertragszunahmen von durchschnittlich 0\9 tha−0[ "2# Fungizide gegen AÝhren!und Halmbasiskrankhe!iten erho�hten die Ertra�ge um 0\11 t ha−0[ "3# Fungizidegegen Blatt!und AÝhrenkrankheiten und alle Kombinatio!nen erho�hten die Ertra�ge im Mittel um 0\48 t ha−0[ Teil!weise wurden Wechselwirkungen zwischen dem Fungi!zideinsatz und den u�brigen Versuchsfaktoren wurden

beobachtet[ Aus den Ergebnissen kann abgeleitet werden\da) die Fungizide gegen Blatt! und AÝhrenkrankheitendie Gerstenertra�ge am sta�rksten erho�hten und dieErtragsschwankungen verringerten[

Acknowledgements

The authors thank O[ Christen\ Institute of Crop Pro!duction and Plant Breeding\ for improving the Englishof the manuscript[ The Sonderforschungsbereich SFB081 was funded by the Deutsche Forschungsgemeinschaft"DFG#[

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