1 Should strobilurins still be used in wheat? Danish and foreign experience Lise Nistrup Jørgensen...

1

Should strobilurins still be used in wheat?

Danish and foreign experience

Lise Nistrup Jørgensen

Karin ThygesenDanish Institute of Agricultural Sciences.

Flakkebjerg

2Danish Institute of Agricultural Sciences Flakkebjerg

Agenda

• 2 years’ trial after strobe resistant septoria have become widespread

• Experiences from abroad

• Experiences with strobilurins for tan spot (DTR) control

• Next years recommendations


Distribution of strobilurin resistance septoria 2004

• Strobilurin resistant septoria in DK

2,5

33

22

81

0

10

20

30

40

50

60

70

80

90

2003 2004

%st

robi

lurin

resi

sten

s

spring

Summer

>75%

<75%


Septoria control with and without strobilurins –

5 trials 2004-2005 -split-ear treatment

50

55

60

65

70

75

80

85

90

2x 0,3 Opus + 2 x 0.2 Amistar + 2 x 0,1 Amistar +2 x 0.2 Comet +2 x 0,1 Comet

% control


Yield increases with/without strobilurins - 5 trials 2004-2005 –split-ear treatments

-202468

1012141618

2x 0,3 Opus + 2 x 0.2Amistar

+ 2 x 0,1Amistar

+ 2 x 0.2Comet

+ 2 x 0,1Comet

grossmargin

Hkg/ha

LSD=3.4


-2

0

2

4

6

8

10

0,5 Opus 0,25 Opus +0,25 Amistar

0,25 Opus +0,25 Comet

0,4 Opus +0,1 Amistar

0,4 Opus +0,1 Comet

grossmargin

Yield increase with/without strobilurins –3 LC trials – single ear-treatments

Hkg/ha

LSD95 = 2.1

Source: Landsforsøgene 2005

7

% control of septoria plus/minus strobilurins 3 trials 2004-2005 – split-ear treatments

0

10

20

30

40

50

60

70

80

90

2x 0,4 Opus 2 x 0,2 Opus + 2 x 0,2 Amistar +2 x 0.2 Comet 2x0,2 Juwel

Danish Institute of Agricultural Sciences Flakkebjerg


Yield increase plus/minus different strobilurins 3 trials 2004-2005 split-ear treatment

-2

0

2

4

6

8

10

12

14

2x 0,4 Opus 2 x 0,2 Opus + 2 x 0,2Amistar

+2 x 0.2Comet

0,2 Juwel

grossmargin

LSD = 2.9

Hkg/ha


Conclusions on Danish trials

• On average little positive effect of adding strobilurins in 2 years trials

• Gain similar to increasing dose of Opus

• Little or no greening effect observed

• Positive effects not dependent on cultivar or nitrogen

10

52 forsøg med høj resistens til strobiluriner QoI(>30%)

3.2

3.9

-2

0

2

4

6

8

10

12

89

18

28

95 2

61

91

10

91

80

86

89

55

76

10

14

76

91

77

10

41

27

80

22

14

50

q/ha

Gain STROBILURINES 100 g/haGain OPUS + 50 g/ha

moyenne gain strobmoyenne gain dose OPUS

French trials with 0.2 strobilurin or 0.2 Opus added to Opus treatments at T1 and T2

Kilde: Claude Maumene Arvalis, Frankrig

+ 0,2 strobilurin

+ 0,2 Opus


French data from strobilurin trials

T1 and T2 Yield increase from adding strobe or Opus hkg/ha

+ 2 x 0.2 strobi

+ 2 x 0.2 Opus

+ 2 x 0.2 Comet

3.3

3.0

-

3.2

3.9

4.0

3.4

1.5

5.4No of trials 82 52 30

Resistant level High >30% Low <30%

Kilde: Claude Maumene Arvalis

Basic treatments with 2 x (0.2-0.6 l Opus)


Conclusions on French trials• 82 trials with +/- strobilurins

– 3.3 hkg/ha from adding 0.2 l strobilurins to Opus (Margin by 0.8 hkg/ha)

• At high resistant levels Opus alone has been best– 80% of trials have given best yield after increase in

Opus dose (+0.2 l) compared with adding 0.2 l Strobilurins

• Comet + Opus solutions equally good as Opus solutions

• Best effect from adding strobilurins at the early application


Experiences from abroad

• Still low septoria resistance in some parts of Europe• Still some effect on septoria – typically around 30%

in fields with high levels of resistance• Still yield increases around 3-4 hkg/ha. Big variation

difficult to explain• Possible explanations:

– Occurrences of intermediate resistant isolates (10-15%)– Preventive effects still significant on resistant isolates– Direct physiological effects, diminishes stress/antioxidants– Comet has been seen to give induced resistance

14

Control of different septoria isolates with varying degrees of strobilurin resistance

Danish Institute of Agricultural Sciences Flakkebjerg

010

2030

405060

7080

90100

0,125 0,25 0,5 1

dosering l/ha

% c

on

tro

l

DG 60 res

UK 35 inter

UK 121 inter

D63 inter

UK19 inter

IR 121 inter

s27 sen

Sensitive isolate

Inter-mediateisolates

Resistant isolate


Preventive or curative effects on septoria

Isolates Preventive treatments

Curative treatments

Sensitive

Resistant 1

Resistant 2

Resistant 3

84

65

27

56

68

18

16

2

Source: Bill Clark, 2005


Recommendations abroad

• Opus/Proline/Daconil main elements in septoria control strategies in our neighbouring countries

• Effect of strobilurins on septoria is seen as secondary• Strobilurins still recommended at late applications

(T3) for control of– Alternaria, Claudisporium etc

– Fusarium/Michodochium

– Brown rust and yellow rust


% control of DTR on 2nd leaf, GS 73-75 - 2005 trials

Treatments at GS 39

Høve Flakkebjerg

Untreated

Bumper 0.25

Proline 0.4

Acanto 0.5

(45%)

78

69

49

(75%)

75

76

80

18

Monitoring DTR sensitivity to strobes

Agar + fungicide

Spore suspension of pure-cultured isolates

Microtitreplate with various fungicide concentrations mixed with agar

0,1

0

1,0

10

1

10

25

ppm/L

Strobilurin

Propiconazole

50


DTR resistant monitoring - DKLocalities Number of

isolatesAmistar

EC50

% Strobi-resistance*

Bjærup (Flak)

Ålborg

Sjælland

Nykøbing F

Skive

Odder

Høve

Flakkebjerg

10

10

13

2

2

10

6

10

0.5

0.1

8

20

>25

>10

8

8

0

0

46

100

100

60

50

20

TotaleTotale 6363 0.1-200.1-20 33 (>10 33 (>10 ppm)ppm)

* Probably G143 resistance

20

Conclusions on strobilurins resistance to DTR

• Strobilurins have shown reduced effects in field trials in Denmark as well as in Sweden

• 8 LC trials have on average given lower effects and yields from strobilurins compared with triazols

• Both F129 and G143 resistance-mechanisms found in Denmark. G143 gives low field performance

• Few isolates tested from 2003-2004. These showed, however common resistance.

• Sensitivity tests from 2005 have shown wide spread resistance, but also variation between localities


Danish recommendations

• Septoria control– Opus alone or Opus + low Strobilurin dose– E.g.: 0.5 l Opus or 0.4 l Opus + 0.1 l Comet/Amistar

• DTR control– Bumper + Opus – E.g.: 0.15-25 Bumper + 0.15- 0.2 Opus– Proline (if and when registration comes in 2006)

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