31 March 1995

PSD no-spray list based on flawed model – NFU

Mistaken modelling is said to underpin the latest list restricting the use of spray chemicals. Andrew Blake delves deeper

MOVES to introduce a list of pesticides which may not be sprayed within 6m (20ft) of a watercourse are under fire as the science behind it is challenged.

Compiled by the Pesticides Safety Directorate last December, the list of more than 150 products is causing concern, not least among chemical advisers. It includes popular products, ranging from relative newcomers like Competitor (fluorglycofen-ethyl + isoproturon) and Logran (triasulfuron) to older ones such as Bravo (chlorothalonil) and Gesaprim (atrazine).

An accompanying note reminds growers that they should always use products in accordance with their labels. If a product attracts the 6m restriction this will appear on the label, it states.

According to NFU pesticide specialist, Dr Chris Wise, the PSD list was drawn up using a mathematical hazard model based on direct overspray instead of taking account of drift. "We believe the model is flawed and at last this has been recognised by PSD."

But despite the setting up of an informal working group between the NFU, the British Agrochemicals Association and UKASTA, a ministry spokesman maintains PSD is "not thinking of rescinding the list or even making deletions".

Without modification the list would "make life extremely difficult for farmers", says Dr Wise.

The NFU is not against buffer zones for water courses, but many of the products listed do not merit a 6m buffer, he claims.

Chemicals vary in their impact on aquatic life. "Sulfonylurea herbicides are particularly good at killing duckweed, and certain fish are very sensitive to pyrethroid insecticides." For these chemicals the 1m (3ft) zone for which the NFU is pressing might not be enough, he concedes.

Dr Wise says a 6m zone could make control of some problems, such as blight in potatoes, almost impossible unless the zone is left unplanted. But the NFUs main concern is that conservation groups could use the list as a lever to press for extra protection for hedgerows.

"You can see the way the environmental lobby is going. We dont mind buffer zones provided they are based on sound science."

&#8226 6m (20ft) buffer zone.

&#8226 >150 products affected.

&#8226 Based on modelling.

&#8226 Science challenged.

&#8226 Husbandry difficulties.

&#8226 Policing problems.

&#8226 Hit list denied.

&#8226 Information flow slow.

&#8226 Label detail is key.

So incompatible that PSD is trying to impose 6m no-spray headlands around all watercourses for a range of leading pesticides.