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Aphids starting to colonize soybean fields

A soybean entomologist says growers should begin watching for aphids.

Bob Koch is with the University of Minnesota and tells Brownfield the pests are starting to colonize in small numbers across the Midwest.

“If growers have had to replant their fields due to hail events or things like that; those later planted fields are often times more attractive to the aphids.”

Fields surrounded by trees and buckthorn are also more susceptible to aphids early in the summer.

Koch says for the remainder of the growing season, populations will be mostly dictated by weather.

“If we get lots of real high temperatures, aphids don’t do very well once we get up into the 90’s where that can slow down aphid population growth.”

Koch points out that even with air temperatures at 90 degrees or above, conditions in the canopy will be cooler.

He says threshold levels are 250 aphids per plant, and it’s not wise to spray preventatively.