Crop pest activity rising as warm weather continues in UK

The recent warm weather appears to be stimulating all sorts of pest activity, which could put crop yields under pressure, say experts.

Pod weevil and pod midge favour dry warm conditions, so growers should check oilseed rape crops during pod formation to see if an insecticide is necessary.

"Seed weevils migrate into crops from overwintering sites, so continue checking crops regularly during flowering and treat only if thresholds are exceeded,” says ADAS entomologist Steve Ellis.

Seed weevils need to feed for a couple of weeks before laying eggs, after which treatment is useless. One weevil per two plants is the spray threshold in the north and one per plant elsewhere, he adds.

Growers planning to apply a product for seed weevil and pod midge should consider beneficial species, says Makhteshim-Agan’s Stuart Hill.

Saddle gall midge

In the south of England the warm weather is thought to be responsible for outbreaks of saddle gall midge in winter wheat crops.

These outbreaks are much earlier than the typical mid-May to mid-June emergence period, say entomologists.  Adult midges are blood red and larger than wheat blossom midge.  Their eggs are also red.

Control must be directed towards newly-emerged larvae as once beneath the leaf sheath, they are difficult to hit with an insecticide.  There are no approved products for saddle gall midge, but a contact-acting insecticide approved for use on cereals, such as pyrethroids, chlorpyrifos and thiacloprid, may be effective.

In pulses, pea and bean weevil continues to be a problem in spring crops and it will be necessary to apply a second spray two weeks after the first application to maintain control of the pest, says PGRO’s Becky Ward.