Oilseed rape growers are being urged to adopt good propyzamide stewardship principles before drilling in the coming weeks.
Corteva Agriscience says field selection, tramline placement and buffer zones should all be considered with the objective of keeping the active ingredient out of watercourses.
Astrokerb and Kerb Flo 500 are the cornerstones of most oilseed rape weed control programmes but are applied in the winter when rain can lead to run-off without good product stewardship.
“By following some fairly simple principles growers are able to keep the active where it needs to be – in the field, taking out weeds,” says Clare Stapley, category manager for Oilseed Rape Herbicides.
“This means your investment is working harder for you, and together we can protect watercourses as well as the future of these vital active ingredients.”
Propyzamide is a selective, systemic herbicide used to control annual and perennial grasses and certain broad-leaved weeds in winter oilseed rape.
Its importance in the herbicide programme has grown in the past decade as it retains the ability to take out grass weeds – most notably black-grass – which are resistant to many graminicides used in cereal crops.
After a heavy rain event there is a risk of propyzamide attached to soil particles getting washed into surface water.
Ms Stapley said: “Oilseed rape drilling is already underway in some parts of the country, but the bulk of the crop will be going in over the next six weeks so it’s a crucial time to consider stewardship.
“Appropriate planning and ongoing management will go a long way towards mitigating the risk to water.”
Ms Stapley advises that stewardship begins with field choice.
“Before seed is sown, consider where you will plant your oilseed rape,” she says.
“Grow oilseed rape in a field which doesn’t slope towards water, that is less susceptible to run-off, or is far away from any watercourses.
“Then, when putting in tramlines, ensure they do not provide a direct route for water to leave a field.”
Use of buffer zones to reduce the chance that run-off could reach a watercourse.
The Voluntary Initiative recommends a six-metre buffer, and, if possible wider buffers are advisable in particularly vulnerable areas such as at the bottom of a slope adjacent to a water course.
Establishment technique, direction of working travel, consideration of soil type and topography are also important parameters.
Propyzamide is vital in keeping problematic grassweeds like blackgrass or ryegrass controlled. Following stewardship practices will reduce the risk of it leaving the field, keeping the active ingredient where it is needed.