An important herbicide for beans and peas is under threat after four decades because it continues to be detected in watercourses.
Bentazone is a one of the few post-emergence herbicides for beans and the only post-em available for challenging weeds in the pea crop, such as black nightshade. It is also used on linseed, alliums and potatoes.
The chemistry is absorbed through the leaves of target plants, disrupting the photosynthesis and causing a reduction in the carbohydrate reserves. But it is highly soluble and mobile in soil – and continues to be detected in ground and surface water.
Manufacturer BASF and the wider agricultural industry have had a stewardship programme in place since 2014. But records show no serious decline in the levels of bentazone detected in water, despite the Better Bentazone Together Campaign.
Bentazone is due review for re-approval in 2025. The Environment Agency – which will be part of the decision panel – has made it clear that the industry must reduce the levels and numbers of detects in water in order for re-approval to be considered.
BASF stewardship manager Paul Goddard said the area of pulses grown in the region could seriously decline without bentazone. And he called on growers to abide by stewardship guidelines and help secure a future for the chemical.
Mr Goddard said: “As bentazone can enter the water courses through both groundwater and surface, there are multiple chances for leaching so we must do everything we can culturally, and chemically, to reduce the levels.”
BASF and industry partners have been working with the Environment Agency and water companies developing ls to offer guidance and support to growers. But Mr Goddard said he felt more could be done on farm.
“This can be as simple as how and where growers fill their sprayer,” he said. “Avoiding high risk areas, ensuring the field is suitable before planting crops and keeping the chemistry on the surface are other important considerations.”