12 May 1995

Blossom midge monitored

OVER half the UK wheat crop will be at risk from blossom midge this summer if the weather suits the pest.

To combat the threat, a scheme to predict spraying needs is to be run jointly by ADAS and DowElanco.

Likely starting date is the beginning of next week. Soil will be sampled at 10 sites across the UK to monitor midge pupation, says James Knight of DowElanco. This provides a guide to when growers should check crops for midge infestation.

About 10% of the crop is at high risk from the pest, and a further 44% at moderate risk. That includes most of the main arable areas, but the midge has also spread to new areas in the south-west, the north-east and the Borders.

Reactivated larvae

However, the weather would have to be perfect for midge development for attacks to reach such levels, says Jon Oakley, ADAS entomologist at Reading. "The warm weather will have reactivated a lot of hibernating larvae. But it is generally too dry at the moment – they wont pupate until it rains."

The forecast is "pretty dry", he adds. "We cant say anything definite for now, but it looks like a moderate year – subject to change over the next few weeks."

Where hatches do occur, growers should monitor fields at early ear emergence for signs of midge. An approved organophosphorus insecticide should be applied to quality crops if more than 100 midges a square metre can be found, and to feed crops if double that number are present, says Mr Knight.