Winter cereal growers should be on the alert to the threat of wheat bulb fly as backward crops could still be susceptible even though an autumn survey indicated a low risk from the pest.

Egg-hatch has now started in Suffolk, Cambridgeshire and Hertfordshire, and many late-drilled crops could be at risk if they only have one or two tillers when the eggs start hatching.

Crop consultant ADAS started monitoring egg hatch last week and together with Dow AgroSciences will issue weekly Pestwatch reports from January through into February.

“Backward crops will be at risk from wheat bulb fly even at lower levels, and with more spring drilling we expect these crops could also be under threat,” Dow AgroScience’s technical specialist Sarah Hurry told Farmers Weekly.

An ADAS autumn survey, sponsored by the HGCA, showed the lowest level of threat from the pest since 1984, with only 3% of sites sampled being above the threshold of 250 eggs/sq m, although subsequent wet weather delayed crop development and may well have increased the risk.

Pestwatch reports will be issued weekly by ADAS and Dow, and the results of the soil samples can be accessed on the Dow website.

The main agrochemical control is via the insecticide chlorpyrifos, and a new industry stewardship initiative “Say no to Drift” campaign’ was launched last season with the aim of protecting the future availability of this chemical by encouraging guidelines such as the use of low drift spray nozzles and using buffer zones alongside watercourses.

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