Wheat crops are approaching the growth stage (GS 53-59) for susceptibility to orange wheat blossom midge (OWBM) attack.
Rothamsted suction traps suggest emergence is now underway, with midge pupation being triggered when the soil is moist and at temperatures greater than 13degC.
Dr Steve Ellis, entomologist at ADAS advises growers to check OWBM-susceptible winter wheat varieties for adult female midges during the evenings, prioritising Group 1 and 2 wheats and seed crops.
He says: “A critical factor will be whether these growth stages coincide with the egg-laying activity of female midges.
“Emergence of male midges can also be monitored at emergence sites using pheromone traps.
“A control threshold is reached in susceptible milling and seed varieties of wheat if an average of one midge per six ears is found.
“For susceptible feed wheat varieties, the threshold is an average of one midge per three ears.
“However, in practice it is difficult to assess midge numbers per ear so if you part the crop and a cloud of midges appears, this can be considered a threshold.”