Azole-based fungicide ban 'would cut OSR yields by 10%'

Oilseed rape yields could be cut by almost 10% if a key fungicide group is banned by EU officials, a report has warned.

The report, written by ADAS for the European Crop Protection Association, evaluates the potential impact of losing the azole group of fungicides if Brussels imposes a ban on health and safety grounds.

It shows UK yield reductions of 9.8%, or about 215,032 tonnes a year.

A ban could be introduced through the new hazard-based approach to pesticide reviews in the EU.

The chemistry may be lost as the European Commission has identified endocrine disruptors, a group to which the triazole fungicides are at risk of being defined, as a possible risk to human health and the environment.

Jonathan Blake, senior research scientist and co-author of the report said: "The impact of losing these actives in wheat has been well documented, however, this report shows that it will be equally as damaging for oilseed rape production.
 
"Although there is a level of substitution with other available chemistry, triazoles are the most effective chemical control measures against all the major oilseed rape diseases.

"Strobilurins and SDHIs would have activity, but the risk of rapid resistance development is high," said Mr Blake.

Pete Gladders, plant pathologist at ADAS added that he believed the major issue would be the control of light leaf spot, with triazoles being the only weapon in the armoury against the disease.

"Looking at crop monitor, the disease has been at record levels this year," said Dr Gladders.

"We could grow resistant varieties on a wider scale, like Cuillin in Scotland and northern England, but oilseed rape would have to be diluted in the rotation and in the North it could be argued that you wouldn't grow it at all.

"Those resistant varieties would also be at risk from breaking down much quicker in the presence of such high disease pressure," he said.

Phoma and sclerotinia are much more weather dependant, continued Dr Gladders. "Phoma can also be managed with new resistant varieties coming through and sclerotinia has biggest range of products available for control, so it is not so critical.

"In addition we would also lose the growth regulatory effects that triazoles give us, which will greatly effect rooting and canopy management, which would be much more difficult," concluded Dr Gladders.

NIAB TAG commercial technical director Bill Clark also asked what the consequences of losing triazoles would be on a global scale. "Lower yields and higher food prices in the EU would also effect global prices and push many more millions of people into starvation," he said.

Key OSR fungicides

• Difenconazole
• Fluzilazole
• Metconazole
• Prothioconazole
• Tebuconazole