Last summer’s warm September may have saved the harvest for Manitoba grain producers, but the mild weather also provided ideal egg-laying conditions for grasshoppers.
“Warm and dry weather in late summer will mean that there has been more opportunity for the potential pest species of grasshoppers to lay their maximum amount of eggs,” Manitoba Agriculture entomologist John Gavloski said in the recently released 2010 Manitoba Grasshopper Forecast.
“The potential for grasshopper populations to increase is to a very large extent determined by the number of eggs deposited.”
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Although that sounds ominous, Gavloski said other factors also contribute to the grasshopper population, such as weather conditions and the number of grasshoppers that were available to lay eggs at the end of the summer.
Manitoba Agriculture staff counted grasshoppers at 203 locations in August and determined that grasshopper numbers were very light – zero to four hoppers per sq. metre – in most of eastern Manitoba. Counts were substantially higher in the western half of the province, with severe numbers of 12 to 24 hoppers per sq. metre around Melita and Neepawa.
Across the province, results from the August 2009 count were similar to 2008. Forty-seven percent of the 203 locations had very light numbers, 25 percent were light (four to eight hoppers per sq. metre, 17 percent moderate (eight to 12 hoppers per sq. metre), 11 percent severe and 0.44 percent very severe (more than 24 sq. metre).
Grasshopper counts in 2009 were down significantly from the earlier part of the decade. Nearly 26 percent of Manitoba had severe or very severe grasshopper conditions in 2002. In 2003, 37 percent had severe or very severe densities.
One area, near Plumas, registered a count of very severe in 2009, but Dennis Beernaert, with Manitoba Agriculture in Gladstone, said grasshoppers weren’t a huge concern there.
“Last year we had the potential (for high numbers), but because of the wet summer we never had a real problem,” he said.
The region is typically a hot spot for grasshoppers, Beernaert added, because of its sandy soil.
“If we get a dry summer and a dry spring… we will have a grasshopper problem.”
Gavloski said producers in western Manitoba should monitor the situation because grasshopper populations are at levels that require early-season scouting.
“We certainly could see an increase in numbers next season if conditions are favourable for the grasshoppers,” he said in an e-mail. “To what extent is hard to speculate on. Farmers and agronomists should scout areas that were more favourable egg-laying sites carefully while the grasshoppers are still young.”
