Pro Operator

Apply autumn herbicides with care

Sands sprayer in field of oilseed rape

Four key active ingredients to control grassweeds in oilseed rape are under threat of restrictions, or possibly even being

banned, unless operators take greater care to ensure they do not pollute water.

The products causing most concern in the autumn are:

  • Propyzamide (eg: Kerb)
  • Carbetamide (eg: Crawler)
  • Metazachlor (eg: Sultan)
  • Quinmerac (eg: Banastar)
Sands sprayer over oilseed rape

It is vital operators, particularly those in high risk areas, follow stewardship guidance before and during applications as well as comply with the buffer zones, maximum dose limits and other advice.

The Voluntary Initiative (VI) is working to raise awareness, improve practices and develop new tools to support farmers and operators in continuing their responsible use of these herbicides.

A Water Protection Advice sheet for each of the active ingredients is available to download from the VI website link HERE 

It is vital operators check these and follow the specific guidance, before and during applications.

Operators need to follow the basic water advice when applying all these autumn herbicides and a mainstay of this is a grass buffer strip at least 6m wide.

All the active ingredients have set maximum dose rates for not only the season but also, in some cases, for the field over a number of years.

For high-risk areas the VI advice sheets provide a simple tick-box assessment for each product.

Examples of ways to reduce risk include avoiding application to soils that are dry, cracked or saturated, recently deep subsoiled or where the drains are running or likely to flow within seven days of application. Other considerations include gradients of field slopes towards water, proximity of watercourses and whether the crop was established using minimum tillage.

Five-step protection process

  • Use to check whether the land is in a Drinking Water Safeguard Zone and if the oilseed rape herbicide you intend to use have been identified as an issue
  • Use the VI Integrated Pest Management Plan and discuss your approach to growing oilseed rape and weed control with your agronomist. Identify if there are any changes to the rotation, cultivation and weed control practices that will reduce the risk of these herbicides reaching surface water
  • Before applying oilseed rape herbicides refer to the VI Water Protection Advice Sheets and follow their advice. Do not apply if drains are flowing or there is a risk of heavy rainfall in the 48 hours after application. If in doubt consult your agronomist
  • Ensure all surface water adjacent to oilseed rape fields is protected by at least a 6m grass buffer strip
  • Ensure your filling, handling and application practices are in good order and there is no risk of spills or splashes reaching water during filling or washing down. Use the VI’s on-line Check it Out tool.


Basic water protection advice

  • Take care when filling and cleaning the sprayer

  • Use at least a 6m grass buffer strip beside water courses

  • Discuss cultivation and spray timing with your BASIS registered adviser

  • Manage soils and tramlines to avoid surface run-off or erosion

  • Do not apply when soils are cracked, dry or saturated

  • Do not apply if heavy rainfall is expected within 48 hours of application.

Field margin with buffer zone to protect wildlife
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