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Should strobilurins still be used in wheat? Danish and foreign experience

Should strobilurins still be used in wheat? Danish and foreign experience. Lise Nistrup Jørgensen Karin Thygesen Danish Institute of Agricultural Sciences. Flakkebjerg. Agenda. 2 years’ trial after strobe resistant septoria have become widespread Experiences from abroad

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Should strobilurins still be used in wheat? Danish and foreign experience

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  1. Should strobilurins still be used in wheat? Danish and foreign experience Lise Nistrup Jørgensen Karin Thygesen Danish Institute of Agricultural Sciences. Flakkebjerg

  2. 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 Danish Institute of Agricultural Sciences Flakkebjerg

  3. >75% <75% Distribution of strobilurin resistance septoria 2004 • Strobilurin resistant septoria in DK Danish Institute of Agricultural Sciences Flakkebjerg

  4. Septoria control with and without strobilurins – 5 trials 2004-2005 -split-ear treatment % control Danish Institute of Agricultural Sciences Flakkebjerg

  5. Yield increases with/without strobilurins - 5 trials 2004-2005 –split-ear treatments Hkg/ha LSD=3.4 Danish Institute of Agricultural Sciences Flakkebjerg

  6. Yield increase with/without strobilurins –3 LC trials – single ear-treatments Hkg/ha LSD95 = 2.1 Danish Institute of Agricultural Sciences Flakkebjerg Source: Landsforsøgene 2005

  7. % control of septoria plus/minus strobilurins 3 trials 2004-2005 – split-ear treatments Danish Institute of Agricultural Sciences Flakkebjerg

  8. Yield increase plus/minus different strobilurins 3 trials 2004-2005 split-ear treatment Hkg/ha LSD = 2.9 Danish Institute of Agricultural Sciences Flakkebjerg

  9. 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 Danish Institute of Agricultural Sciences Flakkebjerg

  10. French trials with 0.2 strobilurin or 0.2 Opus added to Opus treatments at T1 and T2 52 forsøg med høj resistens til strobiluriner QoI(>30%) + 0,2 strobilurin + 0,2 Opus Kilde: Claude Maumene Arvalis, Frankrig

  11. French data from strobilurin trials Basic treatments with 2 x (0.2-0.6 l Opus) Danish Institute of Agricultural Sciences Flakkebjerg Kilde: Claude Maumene Arvalis

  12. 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 Danish Institute of Agricultural Sciences Flakkebjerg

  13. 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 Danish Institute of Agricultural Sciences Flakkebjerg

  14. Control of different septoria isolates with varying degrees of strobilurin resistance Sensitive isolate Inter- mediate isolates Resistant isolate Danish Institute of Agricultural Sciences Flakkebjerg

  15. Preventive or curative effects on septoria Source: Bill Clark, 2005 Danish Institute of Agricultural Sciences Flakkebjerg

  16. 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 Danish Institute of Agricultural Sciences Flakkebjerg

  17. % control of DTR on 2nd leaf, GS 73-75 - 2005 trials Danish Institute of Agricultural Sciences Flakkebjerg

  18. 25 10 1,0 10 1 0 Monitoring DTR sensitivity to strobes Microtitreplate with various fungicide concentrations mixed with agar ppm/L 50 Strobilurin Propiconazole 0,1 Spore suspension of pure-cultured isolates Agar + fungicide

  19. DTR resistant monitoring - DK * Probably G143 resistance Danish Institute of Agricultural Sciences Flakkebjerg

  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

  21. 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) Danish Institute of Agricultural Sciences Flakkebjerg

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