Prairie grasshopper forecasts dialed back in wet weather

The excessive moisture causing seeding delays across much of Western Canada should be good for at least one thing: the wet weather will be detrimental to grasshoppers across the Prairies, according to insect specialists.

However, actual populations will depend on weather conditions in June and through the summer.

Grasshopper forecasts for the three Prairie provinces, based off surveys of adult grasshoppers taken in the fall of 2010 and released over the winter, showed relatively few areas of potential concern heading into the 2011 growing season.

There were no areas of Manitoba showing more than a light risk of grasshoppers, while in Saskatchewan most areas, aside from the southwest corner of the province, were also at low risk for grasshoppers.

In Alberta, low populations were also reported across most of the cropland areas, with the largest areas of concern found in the southern grassland areas. The province’s northern Peace River district could be at risk of grasshoppers, according to the provincial report.

“Grasshoppers like hot, dry weather. They don’t like wet weather,” said John Gavloski, extension entomologist with Manitoba Agriculture, Food and Rural Initiatives at Carman, Man.

However, he added the wet conditions hampering seeding operations and flooding fields in many areas right now will have very little effect on actual grasshopper populations in the summer aside from delaying emergence.

“Heavy rains in June are bad news for grasshoppers,” Gavloski said, noting the eggs are hatching at that time. There may be some localized grasshopper “hotspots,” but widespread problems were not likely in 2011.

Cutworms were an issue in central Manitoba in 2010, and could potentially cause problems again in 2011, said Gavloski. Although, he noted that cutworms should have hatched already, and will not be liking the current wet conditions.

Scott Hartley, insect control specialist with Saskatchewan’s ministry of agriculture in Regina, said there were a few grasshopper “hotspots” in the province last fall, but noted that most of those areas in the south were the hardest hit by late snowfall.

“That doesn’t bode well for the grasshopper populations,” said Hartley. However, he added, the moisture won’t necessarily affect the grasshoppers until they hatch later in the year.

Lentils are also a major crop in the areas of possible concern; Hartley noted that lentils can see yield losses with relatively small concentrations of grasshoppers.

Pealeaf weevil could also cause problems in southwestern Saskatchewan this year, said Hartley. Cabbage seedpod weevils were also posing a potential risk this year, he added.

While wet conditions deter grasshopper populations, the moist conditions could lead to problems with wheat midge. “Wheat midge does poorest under dry conditions,” he said.

“Always something”

Scott Meers, integrated crop management specialist with Alberta Agriculture and Rural Development at Brooks, Alta., said grasshoppers were not expected to be a major concern for crops in the province this summer, as the highest concentrations last fall were in pasture lands.

However, pealeaf weevils and wheat midge could cause some issues in the province, he said.

The lateness of spring seeding, combined with the forecasts calling for hotter temperatures in the next week, will see pealeaf weevils starting to fly at the same time that pea plants are still smaller and more vulnerable.

“The earlier they come into the peas, the more damaging they are,” said Meers.

Wheat midge may also be an insect to watch out for this year. “Late-seeded wheat means that we are likely to have midge emerging at the susceptible stage,” he said.

“There is always something that will like the conditions.”

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