Creating a sticky situation may be among the best ways farmers can learn whether wheat midge poses a threat this year.
Research in 1998 found that placing sticky traps in fields is a good way to gauge the presence of midge, said Bob Lamb of Agriculture Canada’s Cereal Research Centre in Winnipeg. It proved more effective than visiting a field in the evening and trying to count the number of midges flying around wheat heads, although Lamb noted there is value in regular field checks.
“This may not be perfect,” said Lamb, “but it’s better than anything else that anyone is doing.”
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The traps, about the size of a playing card, are coated with a petroleum-based resin similar to Tanglefoot. The cards may be available at grain elevators or greenhouses.
Sticky traps were tested in Manitoba and Saskatchewan fields last year using 10 per field. They were mounted on stakes and placed at the same height as the wheat heads where midges lay eggs.
Lamb recommends placing the traps six to nine metres (20 to 30 feet) into the crop and 15 metres (50 ft.) apart. Place them when the crop is starting to head out, Lamb said. Wheat is vulnerable to the insects between heading and flowering.
The traps should be left for three consecutive nights before counting.
Count the total number of midges on the 10 traps. In Lamb’s measurements, insects were counted on only one side of the cards.
- No midges suggests no worries.
- One to five midges are a concern.
- Five to 20 midges suggest they pose a serious threat to the crop.
“We think that farmers with that number are likely to suffer losses that are significant,” Lamb said.
Last year’s research found a correlation between the number of midges caught on the traps and the number of larvae found on wheat heads or the number of damaged heads.
Work continues this year to improve the sticky trap method. Researchers will try to learn what effects trap spacing has on midge detection.
“It works pretty well,” said Lamb, referring to the use of the traps. “I think it’s what we’re going to end up using to monitor the wheat midge.”
Wheat midge, an insect about half the size of a mosquito, is a menace to growers in Manitoba and most parts of Saskatchewan but is less common in Alberta.
Efforts to develop and test midge-resistant wheat varieties continue and some could be available early in the next decade.
