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Critical time to scout soybeans for defoliators

An integrated pest management specialist is encouraging growers to scout soybean fields for insects.

Bruce Potter with University of Minnesota Extension says the crop becomes more susceptible as it goes through its reproductive phase.

“They can tolerate a little less defoliation now than they could earlier. There’s not as many leaves to be put on and replace ones that are lost. And that plant is relying on its resources a little more right now.”

He expects pressure from defoliators like flea beetles and green clover worm to increase early this month.

“What happens is people tend to overestimate defoliation, so if you’re looking at a field, don’t just look at the worst plants or look at (just) the top of the plant. You’ve got to average that defoliation out on the whole active canopy.”

To do that, Potter recommends taking leaves from the top, middle, and lower stem of the soybean.  He says the university’s treatment threshold is 20 percent defoliation.