Be ready for wheat midge this growing season

By Scott Hartley, P.Ag.
Provincial Specialist - Insect and Vertebrate Pests
Saskatchewan Ministry of Agriculture

The 2016 Wheat Midge Forecast map (PDF) indicates high risk for wheat midge infestations, primarily in eastern Saskatchewan. Most notably in the southeast, an area of high risk extends north, into the east central region of the province. Pockets of moderate to high risk were also identified in the area extending from south of Prince Albert and north of Rural Municipalities 250 and 251.

In Saskatchewan, dry conditions in the spring and early summer in 2015 in many areas affected wheat midge emergence. Dry conditions and late emergence of adult wheat midge may not coincide with susceptible stages of wheat crops. Many of the drier areas in 2015 indicate lower risk from this pest for 2016. If precipitation in an area is less than 25 mm prior to the end of May wheat midge development will be affected again resulting in delayed emergence of the insect.

Sitodiplosis mosellana"Sitodiplosis mosellana" by Gilles San Martin is licensed under CC BY-SA 2.0 / Cropped from original

Areas of infestation indicating over 600 wheat midge per square metre on the wheat midge map may still result in significant damage and yield loss, especially if environmental conditions are favourable for wheat midge. In areas indicating levels greater than 1,200 midge per square metre, producers planning to grow conventional spring wheat as part of their crop rotation are advised to include the cost of insecticide application in their 2016 budget.

To determine midge populations and, if necessary, timing of an insecticide application, growers are urged to monitor conventional wheat fields during the susceptible period (when the wheat head becomes visible as the boot splits until mid-flowering (anthesis)). Regular field scouting on multiple nights in succession is important to understand wheat midge population changes in a particular field. Temperature and wind conditions significantly influence egg-laying by the adult female midge. High temperatures and high winds tend to reduce activity of egg-laying female midge.