HGCA survey reveals low potential threat from wheat bulb fly

Results from this season’s HGCA’s autumn wheat bulb fly survey suggest that the risk from this pest is relatively low. In fact, the overall risk this year is equal to the lowest level risk ever recorded in 1984.

A total of 30 fields were sampled. The sites were split across eastern and northern England, where the pest is historically most prevalent. Only one field was classified as ‘high-risk’, containing egg numbers greater than 250/m2 threshold.

“It is likely that the cold and wet weather had an impact on the number of adult flies and their ability to lay eggs,” stated Caroline Nicholls, HGCA Research & KT Manager.

“However, late-drilled crops, sown after November, or slow developing crops may still be at risk if they have only one or two tillers at the time of wheat bulb fly hatch in January/February. For these crops a lower threshold of 100 eggs/m2 is considered more appropriate,” reported Miss Nicholls.

Steve Ellis, ADAS Entomologist, who conducted the survey on behalf of HGCA added: “In the east of England, 47% sampled sites and 27% of the sampled sites in northern England were above 100 eggs/m2. In these situations, late-sown crops would benefit from an insecticide seed treatment.”