Weed management and erucic acid risks in oilseed rape

Higher than expected levels of erucic acid have been found in seed grown from double-low oilseed rape (OSR) varieties. Weed management in the established crop is essential, as part of efforts to keep acid levels below legal/contractual requirements.

How to minimise erucic acid risks in oilseed rape

How do weeds influence erucic acid risks?

OSR volunteers are the principal cause of elevated levels of erucic acid. However, the high erucic acid status of some weed species means both require controlling.

How volunteers affect erucic acid risks in oilseed rape

Examples of key erucic-acid-producing weeds and crops

  • Bittercress (46%)
  • High erucic acid rape (HEAR) OSR (>45%)
  • Charlock (42%)
  • Black mustard (37%)
  • Hedge mustard (24%)
  • Wild radish (27%)
  • Crane’s-bill (10%)

In cereal crops, volunteers can be controlled effectively with many commonly used herbicides. Controlling volunteers and many erucic-acid-producing weeds in OSR crops is more challenging. Growing OSR on wider rows can allow for inter-row hoeing and inter-row spraying, if suitable equipment and chemistry are available.

Clearfield® varieties, which are tolerant to specific imidazolinone herbicides, also provide an opportunity to manage weeds and volunteers. However, if full control is not achieved, there is a potential risk of volunteers developing with high erucic acid and herbicide-tolerant traits. Clearfield® varieties also tend to be lower yielding than other varieties without the Clearfield® trait.

See the AHDB Recommended Lists for varietal information

How to manage weeds and volunteers in the arable rotation