Wheat Midge Forecast Risk
The Saskatchewan Wheat Midge Forecast Map for 2020 continues to show relatively low risk from the insect pest for much of the province. However, some areas in the northern part of the grain-growing region and, to a lesser extent, in the southeast had higher populations of wheat midge. These numbers are greater than those that have been seen in recent years.
Good soil moisture favours this insect. Although much of the province saw continued dry spring and summer conditions in 2019, some regions saw adequate rainfall for development. At least 25 mm of precipitation prior to the end of May is required for proper development; lower levels reduce emergence of adults. Emergence can be delayed, extended or erratic, and may not coincide with the susceptible stage of the wheat crop.
Some central and western areas saw numbers greater than 1,800 per square meter. Importantly, counts greater 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 springtime environmental conditions are favourable. In 2019, 421 samples were collected to produce the 2020 forecast map. Not all fields are sampled. The intention of the forecast is to provide a regional representation of wheat midge populations present in the fall of 2019.
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 2020, VBs are available in CWRS, CPSR, CWSP, CWSWS, CNHR, CWES, and Durum wheat classes. Visit the Midge Tolerant Wheat Stewardship Team's website for information on midge-tolerant wheat and VBs. Also refer to the 2020 Saskatchewan Seed Guide for information.
You can also consider crop rotation to a non-host crop. 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 2020 forecast map