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.

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.

• 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.