27 November 1998

Strong strategy for


WHEAT growers best strategy for combating eyespot is a routine application at early stem extension of a broad-spectrum spray with activity against the disease.

That approach makes sense because accurate visual diagnosis of the disease is virtually impossible in its early stage, which is when treatment is most effective, says AgrEvos Eileen Bardsley.

According to the companys countrywide wheat stem base disease surveys in 1997 and this year R-type eyespot is by far the most prevalent. The accurate PCR test used showed its incidence ranged from 64% of the crops sampled in southern England to 80% of the crops in the north-west.

Of almost 40% of samples taken from wheat following broad-leaved crops, 62% were infected with R-type eyespot. Probably a two-year break is needed to achieve a significant reduction, suggests Ms Bardsley.

The surveys also shows drilling date does not begin to have a significant effect until late October. Even then over 50% of crops drilled from then on were infected.

"Deep ploughing is useful for reducing eyespot, because the soil it brings up will carry less infective material," she notes. "But minimal cultivations keep that material on or near the surface and spread it around more."


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