Mike Owen has seen some good things happen in crop production during his career as an Extension weeds specialist at Iowa State University (ISU). Bad things often come to his mind first, though. He pointed out several examples to those attending this month’s ISU Integrated Crop Management Conference.

·      “When I got here, woolly cupgrass was not on anyone’s radar,” he says. “It became a huge issue in the Midwest within 10 years.”

Fortunately, the mid-1990s debut of glyphosate-tolerant systems curbed many woolly cupgrass infestations.

This hasn’t been the case with all weeds, though. “In the 1980s, no one knew what common waterhemp was,” says Owen. Now, this weed has biotypes that resist multiple herbicide modes of action.

·      The corn-soybean rotation generally held corn rootworm in check in the 1980s. No more. Extended diapause in northern corn rootworm and variant populations of the western corn rootworm have emerged in more areas to nix crop rotation as a control measure.

·      Little was known about maladies like soybean cyst nematode, white mold and Sudden Death Syndrome in soybeans in the 1980s. Now, they consistently threaten Midwestern soybean production.