WHEAT GROWERS have been warned that attack from Orange Wheat Blossom Midge is imminent in crops reaching the ear emerged stage.

“Average pupation percentages have increased to 28% from only 0.1% in the past week,” reported David Roberts, technical services leader at Dow AgroSciences.

“The highest level was found in Herefordshire, with the percentage of OWBM at the pupal stage present in the soil topping 70%.”

Kent, Bedfordshire, Shropshire, Staffordshire, North Yorkshire and Worcestershire also show the most advanced pupation, and are at the highest risk, according to Dow‘s PestWatch report, issued on Friday (May 28).

Latest counts from Makhteshim Agan‘s Bug-Watch has given similar results, according to technical services manager, Elizabeth Spence.

By the end of May 2003, the mean percentage number of OWBM as pupae in surface soils was just 8.6%.

“We are definitely seeing higher levels of the pest compared to 2003,” said Ms Spence.

“Pupation is presently most advanced at sites in the south-west Midlands and in northern England.”

Emergence will be favoured by warming soils and increased moisture following periods of rainfall, said Mr Roberts.

He recommended growers identify high-risk fields, and consider using traps at the most susceptible sites.

“The best time (to check wheat fields) is in the early evening, using thresholds of one midge per six ears for crops intended for seed or milling market, and one midge per three ears for feed wheat,” advised Mr Roberts.