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Soybean defoliation guidance tweaked for applicators

The North Central Soybean Research Program is making the first update to soybean defoliation guidance for the first time since the 1980s.

Michigan State University entomologist Chis Difonzo tells Brownfield intensive on-farm defoliation threshold surveys were conducted over three years across the 13-state region.

“And we never saw a field that would have been over threshold across the whole area—Illinois, Indiana, Iowa, Michigan, and Ohio,” she shares.

Difonzo says farmers need to consider whole plant damage throughout the field, and there’s rarely a need to spray.

“You might have a bad edge, but a lot of times soybeans grow out of that, and right now we have a lot of Japanese beetles coming out and feeding, but that diminishes by the end of the season,” she says.

She says the guidance tweaked thresholds somewhat lower during early growth stages and during pod fill. Finalized thresholds will be published in the fall.