2 June 1995

OVER-SPRAYING FOR BYDV

BARLEY yellow dwarf virus continues to stimulate excessive use of autumn insecticides, according to Keith Walters and Ian Barker. BYDV is seen as a widespread, high risk problem, they say. Coupled with the relatively low cost of treatment, this perception seems to encourage farmers and advisers to spray routinely for aphid control.

Forecasting and modelling the occurrence, intensity and timing of autumn aphid flights, host crops and subsequent breeding potential should help growers target their autumn aphicides more effectively, say the researchers.

It should also reduce the effects of such broad-spectrum insecticides on non-target and potentially useful predators.

Over use of such pesticides has a big impact on such beneficial insects, warns the CSLs David Powell. "In these days of integrated crop management such insects have an important role to play. They should be encouraged and certainly should not be the innocent victims of non-target effects of insecticides."