Dow AgroSciences Pestwatch service for Wheat Blossom midge is reporting adult midge activity over the last 10 days in the Southern counties, East Anglia and Yorkshire.image expired

Sarah Hurry of Dow AgroSciences says that farmers and agronomists are already seeing “clouds” of midges, although activity appears to be variable.  “Counties where adult midges have been reported include Hampshire, Oxfordshire, Wiltshire, Gloucestershire, Kent, West Sussex, Hertfordshire and Yorkshire. Some pheromone traps have caught midges up to threshold levels, whereas other traps have not caught any. ADAS have now confirmed pupation in Wiltshire, Herefordshire and Yorkshire. It is likely that the main period of emergence is yet to come.”

“Orange Wheat Blossom midge larvae need certain conditions (70 days at <10°C) to break diapause, after which larvae move towards the soil surface. They usually require sufficient rainfall to wet the soil to a depth of 10mm and soil temperatures above 13°C to stimulate pupation. Despite conditions being dry this spring, sporadic showers will be sufficient to trigger pupation. Comment has been made this year about the possibility of large cracks in dry soils allowing midge emergence. Windy conditions have also meant that activity has been variable throughout the day.”

Sarah points out that the Wheat Blossom midge risk depends on the vulnerable growth stages of the crop coinciding with egg-laying activity.  “In recent warm weather, wheat crops have developed rapidly. In good conditions, each female midge lays their eggs on emerged ears, before flowering between GS53 and GS39. Eggs hatch usually within 4-10 days, depending on temperature, when the emerged larvae move to the developing grain and then feed for 2-3 weeks. Growers and advisors can go to http://www.dowagro.com/uk/cereal/pest.htm to monitor midge activity, assess risk and optimize spray timings to ensure effective pest control and to minimize impact on the environment.”

“Susceptible sites are those wheat fields where the pest was a problem last year, especially if no treatment was carried out. The economic risk is highest in crops intended for seed or milling, with a threshold for treatment being one midge per 6 ears.  The threshold for feed wheat is one midge per 3 ears. Applications of Dursban WG are now being applied where thresholds and crop stages have been reached.”

Sarah Hurry advises that provided thresholds are met, growers should apply Dursban WG at 0.6 kg/ha in 200 to 1000 litres of water.  “Dursban WG will control all the stages of the pest, giving the grower a wider spray window and more flexibility to control this damaging pest. It gives effective knockdown of adult midges, persistence of 7 to 10 days to control further flights of adults as well as persistence and vapour action to control larvae emerging from eggs laid by the first flight of adults.”

“In association with FWAG, Dow AgroSciences recommend a voluntary 12 metre buffer from the edge of the field as part of integrated pest management best practice. Field boundaries act as reservoirs of natural enemies providing shelter and alternative food sources such as pollen and smaller invertebrates. Many species will rapidly recolonise the cereal crop.”

For further information, please contact Sarah Hurry, Dow AgroSciences on the Dow Technical Hotline on 0800 689 8899.