Club root is becoming an increasing problem in oilseed rape crops and growers should take precautions to minimise the risk of the disease spreading, the Home Grown Cereals Authority (HGCA) has advised.

While the disease is a particular problem in Scotland, incidence has also increased in England in recent years, said the HGCA’s director of research, Graham Jellis.

“The warm autumn last year with high September rainfall was very favourable for infection in England. Once established, control is difficult, but rotation, drainage, liming and resistant varieties [e.g. Mendel] all help.

“If club root patches begin to appear, growers should use lime to achieve a soil pH of at least 7.2 and extend rotations to achieve breaks of at least five years between susceptible crops.”

Minimising the movement of infected soil on farm equipment or via feed swedes or turnips will also help stop the disease spreading.

Club root risk factors:

  • Short rotation oilseed rape
  • Land used for swedes
  • Warm (16-25C), wet or waterlogged soils
  • Winter oilseed rape most likely to be infected during August or September, and from May onwards
  • Cruciferous weeds, e.g. Shepherd’s purse and oilseed rape volunteers, may contribute to survival in the absence of susceptible crops
  • Spores can survive in soil for 10-20 years

Further information on controlling the disease can be found in a new HGCA Topics sheet number 92 ‘Club root in oilseed rape’ – available at www.hgca.com