20 September 1996

Frit fly damage

hard to avoid

this autumn

BE prepared for frit fly damage to cereals this autumn, warns ADAS. Signs are that it will be a high risk season.

DowElanco claims monitoring shows the threat is the highest since 1988.

The flies are already active, laying eggs on grass and volunteer cereals, larvae from which will cause dead-heart shoots from November onwards, says ADAS.

Defence

Main defence is to ensure green material is destroyed between now and drilling, it advises. A four-week interval between destruction and sowing will significantly cut the risk of larvae transferring to new crops.

Where direct action is required, chlorpyrifos insecticide at various timings is an option, as are triazophos post-crop emergence or when damage is first seen and fonofos seed treatment.n