1 March 2002

Next generation of fungicides will rule out reduced rates

Advice to help growers

protect crops at least cost

was to the fore at the

Crop Protection in Northern

Britain conference in

Dundee last week.

David Millar reports

OVER-FORMULATED new cereal fungicides may not give growers the same scope to reduce rates as existing products, according to Peter Mercer, a plant pathologist with the Department of Agriculture and rural Development in Northern Ireland.

Following eight years of trials in winter wheat and spring barley, he said it was possible to reduce fungicide doses to as little as one-eighth of the recommended dose for wheat varieties with some Septoria tritici resistance or barley varieties with mildew resistance without harming profitability.

But Dr Mercer warned that the scope for profiting from reduced rates would change with grain prices, disease spectrum and varietal disease resistance. "Efficacy is also becoming more contentious, because agrochemical companies are not approving low rates for products, which are over-formulated."

Such products are designed for use at specific concentrations, so might not be effective at reduced rates in future, he said.

His trials with winter wheat showed top yields might be obtained from full doses of triazole or strobilurin fungicides, but best profits came from half-dose applications, which typically gave an extra 8% profit.

Both two and three-spray programmes gave substantial extra profit in Septoria susceptible wheat varieties. But there was negligible extra profit or even a decrease in profit from extended programmes on resistant cultivars. &#42

Rate cuts may not be so easy with new generation fungicides, according to research reported at the Crop Protection in Northern Britain conference last week.