The recent hot weather has seen cabbage stem flea beetle (CSFB) numbers explode, with some oilseed rape growers spraying at night when numbers appear higher in an attempt to get on top of the pest.
Tim Beaver, who farms 520ha (1300 acres) in South Lincolnshire and drilled 100ha (250 acres) of OSR has lost 16ha (40 acres) of the crop to CSFB and is taking action to mitigate further losses.
“Numbers seem to increase ten-fold at night so we’ve been spraying at night. We haven’t had a problem with cabbage stem flea beetle before.”
Mr Beaver drilled OSR from August 27-28. “We didn’t expect to have the flea beetle. It was a compact seedbed and we had a nice bit of rain. It happened just as it was coming through. The crop was there one day and gone the next.”
He has been using Hallmark Zeon (lambda-cyhalothrin) in an attempt to control the pest. “I think it is slightly better on the beneficials. It is more selective than cypermethrin and there seems to be less resistance.”
From mid-August to the first week of September, flea beetle levels were generally low and showed no signs of causing a problem, according to Indigro independent agronomist Luke Wheeler, who is based in Leicestershire.
“However, the hot spell in the middle of the month has caused populations to explode and widespread damage. Smaller crops, drilled at higher seed rates, are most at risk and flea beetle sprays are now being applied with the hope that resistance is not going to be too much of a problem.
“Staying vigilant and proactive is essential, to protect the crop until it is robust enough to cope on its own as pest populations decline into winter.”