Wheat Midge Forecast Risk
The Saskatchewan Wheat Midge Forecast Map for 2019 continues to show reduced risk from the insect pest for much of the province. Only a few areas, in the northern part of the grain-growing region and in the southeast, were identified to have higher populations of the wheat midge. Numbers in these regions appear higher than those from last year.
Good moisture favours this insect. Continued dry conditions in 2018 in much of Saskatchewan are the primary reason for the decline in wheat midge populations. Research has shown that if there is less than 25 mm of precipitation prior to the end of May, midge emergence will be affected. Emergence of the adult flies can be delayed, extended or erratic and may not coincide with the susceptible stage of the wheat crop.
Keep in mind that areas of infestation indicating more than 600 wheat midge per square metre (yellow and orange) on the wheat midge map may still result in significant damage and yield loss, especially if environmental conditions are favourable for the wheat midge. Not all fields are sampled. In the soil survey, 420 samples were collected to produce the 2019 forecast map. The intention of the forecast is to provide a regional representation of wheat midge populations present in the fall of 2018.
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 successive nights 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.
There are options for managing wheat midge. If spring wheat is planned as part of a rotation, there are midge-tolerant wheat varieties available as varietal blends (VB). For 2019, VBs are available in CWRS, CPSR, CWSP, SWS, CWES, and CWAD (durum) wheat classes. Visit the Midge Tolerant Wheat Stewardship Team's website for information on midge-tolerant wheat and VBs. Also refer to the 2018 Saskatchewan Seed Guide for information.
Crop rotation to a non-host crop can also be considered. Since spring wheat is the primary host for wheat midge, planting a non-susceptible cereal crop (e.g. oats, barley) or a broadleaf crop (e.g. canola, pulse) is a good option.
Download the 2019 forecast map