Wheat midge is unlikely to be a major pest for the vast majority of Saskatchewan in 2016.
There are only a few hot spots on the 2016 wheat midge map where producers need to be wary.
“It’s fairly positive,” said Mitchell Japp, cereal crop specialist with Saskatchewan Agriculture. “There (are) relatively few areas that show up at high risk for infestation.”
The area with the biggest risk is in the extreme southeastern corner, where in excess of 1,800 cocoons were detected per sq. metre of soil.
The infestation extends in a band stretching from Estevan north past Yorkton, but most of that area is in the more moderate risk category of 600 to 1,200 cocoons.
There is also a narrow band stretching from south of Prince Albert to north of Moose Jaw, where the risk ranges from 600 to more than 1,800 cocoons.
Japp said anywhere the count reaches 600 or higher, growers should budget for insecticide or grow a midge tolerant variety.
Growers in risk areas are encouraged to scout fields during the susceptible stage of crop development, from the time the head becomes visible as the boot splits until mid-flowering.
Insecticide is recommended when there is at least one adult midge for every four or five wheat heads. At that level of infestation, wheat yields will be reduced by about 15 percent if the pest is not controlled. Yield damage will be greater at higher midge densities.
Growers should scout fields on multiple nights to monitor population densities because helpful parasites could be controlling the pest.
Wheat midge also reduces crop quality. The Canadian Grain Commission limits midge damage in No. 1 CWRS and No. 1 CWAD at two percent and in No. 2 CWRS and No. 2 CWAD at eight percent.
In areas where growing conditions are conducive to producing No. 1 wheat or durum, the threshold changes to one adult midge for every eight to 10 wheat heads during the susceptible stage of crop development.