Metazachlor and Quinmerac Water Stewardship

Updated December 2019

Protection of Water: Best Practice Advice

Why Metazachlor matters

Oilseed rape is an important break crop in the arable rotation. It is especially important on heavy land where spring crop establishment can be difficult.

Metazachlor and quinmerac are a foundation for winter oilseed rape weed control programmes and so are key active ingredients for the crop, but in common with some other major herbicides, they have been detected in watercourses at levels that risk non-compliance with the Water Framework Directive (WFD), the legislation drawn up to protect all surface and ground waters.

The water companies report that if they cannot show progress in reducing pesticide concentrations in raw water abstracted for drinking water supply, there will be further restrictions on chemistry. To date, DAFM has looked at voluntary measures to deliver WFD compliance with regulation being the approach of last resort, understanding growers’ needs and the agronomic challenges they face.

Joint initiative from BASF and Adama

BASF and Adama joined forces on a European basis in 2016 to develop stewardship guidelines specifically for metazachlor and quinmerac. Following the guidance will help to mitigate the threat to water.

Propizamide, carbetamide and clopyralid; other OSR herbicides found in surface waters

With all key OSR herbicides having been found in surface water and under threat, stewardship applies to all. Through the use of best management practice (BMP) and by maintaining the number of herbicide options, OSR weed control will be managed into the future.


Drained fields, including temporary – aim for 1st October, cut off 15th October

Applications after 1st October can be made as long as soil and seedbed conditions are good and drains are not flowing

How can OSR herbicides reach water?

The major route is via field sources such as surface run-off or via field drainage. Spillages are also an issue, which need to be avoided. Field sources represent a far greater challenge, with minimisation reliant upon sound agronomics.

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