Spring wheat is at risk from Wheat Blossom midge too

With much less winter wheat and much more spring wheat in the ground, growers, particularly those new to growing spring wheat, need to know that this crop is at risk from Orange Wheat Blossom midge the same as winter wheat. However few spring wheat varieties are naturally resistant to this pest, unlike winter wheat. The same criteria apply in that the crop needs to be at the vulnerable stage of GS 53 to 59 and the Wheat Blossom midge adults need to be emerging.

Dow AgroSciences latest and final Pestwatch for this season reports that adult midges are being found across England, despite low population numbers in the original survey. Midges were particularly active from the South coast up to the Yorkshire Wolds. The advice remains the same - growers should identify fields most at risk with regard to the crop growth stage and consider using pheromone traps at the most susceptible sites. These are typically wheat fields where the pest was noted last year, especially if no treatment was carried out. Crops should be visually inspected on warm, still evenings. Growers and advisors must optimize spray timings to ensure effective pest control and to minimize impact on the environment.

Sarah Hurry of Dow AgroSciences explains the economic risk is highest in crops intended for seed or milling, which is reflected in the lower threshold of one Orange Wheat Blossom midge per 6 ears. The threshold for feed wheat is one midge per 3 ears.

Sarah advises that if chemical treatment is justified by thresholds being met or exceeded, growers should use Dursban WG at 0.6 kg/ha in 200 to 1000 litres of water between ear emergence and the start of flowering (GS51-59) in winter and spring wheat in order to control developing larvae. If justified, treatment should start once the majority of ears have emerged. Ears not emerged at the time of treatment will not be protected.

“Precautions must be taken to minimise any impact against wildlife by only applying an effective insecticide when necessary. Firstly, if treatment is necessary, growers will need to consider beneficial insects. All major groups of insecticides pose a potential risk to beneficial insects when sprayed during the summer and during the Wheat Blossom midge risk period. Adopting a 12 metre no-spray buffer zone beside hedgerows or grass strips will allow an area for beneficial arthropods to survive and re-colonise the field. Secondly growers should comply with ‘Say No to Drift’ stewardship advice. This includes using LERAP three-star low-drift nozzles and adopting a 20 metre no-spray buffer zone beside watercourses. Growers and advisors can go to www.saynotodrift.co.uk/arable/ for details,” points out Sarah.

Dursban WG (75% w/w chlorpyrifos formulated as a Water Dispersible Granule and packed in a 1 kg pack) is recommended for the control of Wheat Blossom midge, Leatherjackets, Wheat Bulb fly and Frit fly. For Wheat Blossom midge, apply Dursban WG at 0.6 kg/ha between ear emergence and the start of flowering (GS 51-59) in winter and spring wheat.