23 February 1996

Cereal respray advice

CEREALS still infested with grass weeds after autumn herbicide treatment could soon need respraying as isoproturon (IPU) "runs out of steam," says ADAS.

Low winter rainfall and cool conditions seem to have given IPU a slightly longer life this season, says Huntingdon-based John Garstang. But leaching and degradation figures suggest pre-December treatments on light soils will no longer be working, so foliar acting products should be applied as soon as the ground allows.

Computer predictions suggest IPU has broken down "significantly slower than the long-term average" in the West Midlands and East Anglia, according to Steven Bailey of the Wolverhampton plant clinic. "This suggests that IPU applied later than about the third week in November to medium soils in these areas may still be providing some weed control," he says.

&#8226 Low leaching conditions this winter should mean IPU levels will not be the problem in water they have been in previous years, adds Mr Garstang.