Farmers in most areas of Saskatchewan need to be aware of wheat midge, says Scott Hartley, Saskatchewan’s provincial specialist for insect pest management. Specifically, eastern Saskatchewan, primarily east central and southeast. There’s another section from Prince Albert south, “extending quite a ways, at least down to close to Bethune.”
Midge threats in Alberta aren’t as high, but are more pronounced east of Edmonton and in the Peace region. However, Alberta Agriculture and Forestry warns that individual fields may have high economic levels, as variability from field to field has been high in the past.
The severity of the problem, Hartley says, will be dependent on climatic conditions. Wheat midge, he says, is favoured by moist conditions, so if we have a wet growing season, there’s a higher risk of wheat midge flourishing.
What can you do?
If you’re growing wheat (other than winter wheat), especially if you’re not growing some of the newer midge-tolerant varieties, you’ll want to keep an eye on the calendar.
“Late June to early July is usually the start of midge emergence across most areas, but this will depend on where you are” and the climate conditions, mostly temperature, says Hartley. During that key time period, monitor your fields. Ideally, says Hartley, “in the evening to give you an idea what your midge populations are like. Usually we recommend one midge per four to five wheat heads as being a reasonable economic threshold, mainly for yield.”
If you’re looking for “top quality wheat, a durum or equivalent” for particular specialty markets, where buyers may have tighter standards, then one midge per eight to 10 wheat heads is what you’ll be looking for, says Hartley.
Pay attention to the “susceptible period, which can be affected by the timing of crop growth. Wheat is most vulnerable to midge damage as soon as the boot splits and any part of the head is visible until we see anthesis, which is flowering. If your plants get past the flowering stage and there’s no midge present yet, then the threat lessens because the plant has built up its natural resistance,” says Hartley.
If you’re above the economic threshold for the varieties you’re growing, you’ll want to apply an insecticide. Where there is variability within a field, Hartley says, you may be able to spot spray and “highlight certain areas and cut down on costs.” However, “in many cases it’s a case of full field spraying.”
For risk warning maps and other information about all kinds of Prairie pests, visit the Prairie Pest Monitoring Network’s blog.
The site is updated throughout the growing season and includes wind trajectory updates and detailed information about insect pests.
The site is funded by the federal and provincial governments as well as a number of check off organizations.
Manitoba is not included in the wheat midge map, however, risk maps for other pests do include information about Manitoba.