28 November 1997

Sleepy rape seed

OILSEED rape varieties show big differences in seed dormancy, which could help growers avoid problems with novel oil and genetically modified herbicide tolerant varieties in subsequent crops.

Work at IACR Rothamsted shows some varieties like Apex, Nimbus and Mars can remain dormant for 5-10 years once buried. Others like Falcon, Acrobat and Industry emerge quickly, allowing easy control in a following cereal crop.

Leaving rape stubbles undisturbed for three to four weeks after harvest avoids the problem. But dark, dry conditions, typically caused by ploughing soon after combining, triggers dormancy in prone varieties.