8 August 1997

Wheat bulb fly advice

CEREAL growers in areas usually at high risk from wheat bulb fly attack should avoid unnecessary cultivations on fields to be sown to cereals.

But land destined for non-host crops should be cultivated now.

Lots of egg-laying females have been trapped this summer, after last winters attack, which was the worst for at least a decade, says John Young, ADAS entomologist at Boxworth.

Egg laying is at a peak now, and will gradually decline through August. Freshly cultivated fields are favoured, as are bare fallows and soil beneath root crop canopies.

"Growers planning to drill oilseed rape or other non-cereal crops will, by cultivating now, attract egg-laying females into fields. When they hatch, grubs will die in the absence of host plants. In effect, the field acts as a trap, reducing the burden on other areas of the farm," says Mr Young.

Conversely, leaving cereal land uncultivated, to the end of August if possible, will help prevent attack, since flies are not attracted to undisturbed ground.n