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Aphid populations worst in central Minnesota

Soybean aphid populations are on the rise in Minnesota.

University of Minnesota Extension entomologist Bob Koch says the largest numbers are in the central part of the state.

“Stearns County area westward towards Willmar, and now even Morris.  We’re seeing aphid populations increasing to near treatable levels in some fields.”

He tells Brownfield central Minnesota missed out on some of the heavier rains earlier in the growing season.

“And we know that when soybean plants are small, if there’s heavy rains and strong winds, that can really take a toll on the aphid populations.  So I think that’s maybe why we’re seeing fewer aphids in northwestern Minnesota and parts of southern Minnesota because we know the storms we had in those areas.”

Koch cautions against treating soybean fields that aren’t at the economic threshold of 250 aphids per plant.  For fields at threshold, he says growers have about a week to apply an insecticide to effectively knock populations down.