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Scouting for wheat midge

Jul 10, 2020 | 12:36 PM

MELFORT, Sask. – Grain farmers in east central Saskatchewan should be scouting their fields for wheat midge.

The adult wheat midge is a very small, orange fly about half the size of a mosquito. It emerges from the pupal stage in late June or early July. In the evening, females begin laying their eggs on the newly emerged wheat heads. The small orange larvae hatch and then feed on the surface of developing kernels causing yield loss and downgrading.

Saskatchewan Ministry of Agriculture crops extension specialist Samantha Marcino based in Yorkton said wheat midge need decent soil moisture in order to develop.

“Even though it has been fairly dry in parts of the province there has been spotty rains,” Marcino said. “For areas to have enough moisture you need at least 25 millimetres of rain before the end of May for proper development.”

Marcino said midge may not be a problem, depending on the stage of plant growth but after talking to producers in the area, there are wheat midge appearing.

“You have to scout for wheat midge at night preferably after 8:30 p.m. It has to be warmer than 15 degrees Celsius with no wind,” she said.

Once wheat midge are found it’s time to determine the threshold.

“The first threshold is one midge to four or five heads. That is the threshold for yield loss. The other is one midge per eight to 10 heads for grade loss. If you find those thresholds an insecticide may be warranted,” Marcino said.

Farmers need to keep in mind there are natural predators that will attack wheat midge.

Crops in the east central region seem to be at the normal stage of development. There have been some showers in the area and with the recent heat crops are progressing quickly.

Marcino said in terms of timing and scouting farmers should be checking now.

“It’s one of those things you don’t realize your wheat may be in the boot stage already but it’s something to take a look at because that is a susceptible stage,” she said.

alice.mcfarlane@jpbg.ca

On Twitter: @AliceMcF