20 October 1995

IPUguidelines need refining is reaction

MOVES to refine advice to prevent isoproturon (IPU) herbicide getting into drinking water seem likely, as reactions to the industrys guidelines gain ground.

The IPU stewardship programme was launched this autumn by a "Task Force" consisting of chemical firms Agrevo, Ciba and Rhône-Poulenc (Arable, Sept 8).

Some of its content, such as not using pre-emergence sprays on wheat or barley, may eventually be included on labels. But it is already under fire for giving conflicting messages.

Its supposedly practical advice is confusing growers on heavy land, especially those with resistant blackgrass, claims Berks-based independent agronomist Laurence Sim.

In particular the recommendation to "always plough as deeply as practicable" jars when set against the need to "create fine, consolidated seed-beds", he says.

"Weve got to accept that IPU is on probation and weve all got to take care. So the task force guide is laudable. But some of the guidelines are easier to talk about than to put into practice in the field."

Sits uneasily

Advice to avoid mole-draining in the season before cereals sits uneasily beside an instruction not to apply IPU to waterlogged soils, he adds.

Spokesman for the Task Force, Rhône-Poulencs Bob Joice, concedes the whole industry is "on a learning curve". "Weve outlined the steps to minimise IPU loss. Our message to individual growers is: Do as much as you can."

Use of the word "practicable" when referring to ploughing recognises that what suits one soil type may not suit the next, he adds. "Were more than happy to talk to people who have difficulties."

A recent Pesticides Safety Directorate meeting with a wide range of interested parties highlighted the problem of defining "heavy" rain in the context of sticking to the guidelines, admits Terry Tooby, PSDs deputy director of approvals. "We can appreciate the conflicts."

One of the keys to keeping IPU where needed is to close up the soil macropores which allow bypass flow, he say. "It is up to farmers to use the most appropriate method. We welcome feedback."