SDHI resistance found in France and Germany
First signs of disease resistance to a new range of SDHI fungicides have emerged in France and Germany, which is seen as a wake-up call to possible troubles ahead for British growers.
Reduced sensitivity to these SDHI products was found in a septoria isolate in a northern France wheat crop and also in two net blotch isolates in barley across northern Germany during 2012.
Global monitoring group, the Fungicide Resistance Action Committee, reports that the resistance factor was low and fungicide performance was unaffected.
“They are mutations that give a partial rather than complete resistance, or a slight shift in sensitivity,” said Fiona Burnett at Scotland’s Rural College.
“These are the first examples; they may spread or they could be a one-off. It very much depends on how we steward these products from now on.”
Fiona Burnett, Scotland’s Rural College
She added there was concern about the risk of resistance ever since the SDHIs were launched.
Many SDHI products were introduced in mixture with popular triazole fungicides – such as Adexar, Aviator and Seguris – and used widely in Britain in the past two seasons.
“These are the first examples; they may spread or they could be a one-off. It very much depends on how we steward these products from now on,” Dr Burnett said.
Bill Clark, commercial technical director at NIAB TAG, agreed and stressed the importance of using SDHIs in mixtures during 2013.
“It’s a wake-up call. We would expect to see some loss of sensitivity over time, especially in a disease like net blotch with its multiple and rapid cycling.”
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