ONE OF the UK‘s biggest water suppliers is calling for a ban on a widely used cereal herbicide.

Thames Water Utilities‘ Dinah Hillier confirmed at the BCPC seminar in Glasgow that the firm is to ask the Pesticides Safety Directorate to outlaw isoproturon.

Diffuse IPU pollution from fields costs far too much to clean up, explained Dr Hillier.

“We have to face the fact that the scale of the problem is too large and, like atrazine, bite the bullet and ban it.”

Bayer CropScience‘s product stewardship manager Steve Higginbotham countered that the call for a ban was “premature and risks undermining the Voluntary Initiative”.

“IPU is still a very valuable herbicide and there is no reason to ban it. It satisfies the requirements of Annex I listing which demonstrates no environmental impact through correct use.”

Losing IPU, a valuable component in blackgrass control programmes, would be an agronomic blow, added ProCam’s David Ellerton.

“If we had a ban it would have big resistance implications.”

TWU‘s move comes despite VI efforts to cut the amount getting into the rivers TWU uses to produce most of its drinking water.

Dr Hillier acknowledged that good progress had apparently been made in lowering IPU levels in the Cherwell river in Oxon, the site of a VI exercise to monitor farm practices‘ impact on water contamination.

Indeed, last season saw a dramatic fall in the amount reaching the river, nearly achieving the VI‘s target of a 50% reduction.

“It sounds good news, but I have a word of caution. The river flow in 2003/04 was the lowest in seven years.”

Rainfall largely determines how much of the herbicide reaches the river, and diffuse, not point source, pollution is the main culprit, she pointed out.

She took issue with the VI view that 40% comes from farmyards during sprayer filling and cleaning.

“Our data suggest that in bad [wet] seasons 90% comes from fields. Tinkering around with activities in the farmyard will not help with IPU. It may do with other chemicals, but not IPU.”