There is a threat from pollen beetles this season, as they start to move off the winter crop at the end of flowering. Spring oilseed rape at green-yellow bud is the key risk timing. One pollen beetle per plant can often cause enough damage to reduce yield. Check spring rape crops regularly until the onset of flowering and apply an insecticide if more than one beetle per plant is found throughout the crop.
Resistance in pollen beetles to pyrethroid insecticides is present in Scotland. The advice to growers is that pyrethroid insecticide use for pollen beetle control should only be used if the treatment threshold of one beetle per plant at green-yellow bud has been exceeded. Do not apply a pyrethroid insecticide to flowering oilseed rape for pollen beetle control – it is not needed as the beetles can get to the pollen without damaging the crop.
If there is any suspicion that you may have pyrethroid insecticide resistant beetles because of poor control, contact your local FAS consultant so that we can arrange for beetles from that crop to be tested, and help us to build up a profile of how widespread resistance to pyrethroids may be.
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