Don’t Sacrifice Weed Control For Later Cover Crop Stands

By: Gil Gullickson

Gregg Johnson is a fan of cover crops.

“I am all for them,” says Johnson, who works with biomass cropping systems at the University of Minnesota’s Southern Research and Outreach Center (SROC) at Waseca. “But we can’t compromise on weed control to take advantage of the benefits of cover crops.”

Preemergence and postemergence residual herbicides are great for managing weeds throughout the growing season. One downside, though, is they can stunt the growth of cover crops that are seeded in late summer/early fall.

Johnson told those attending this week’s SROC summer tour that it’s hard to pin down the effect residual herbicides can have on cover crops planted later in the season. Results are mixed in university trials.

In one year, use of Flexstar and Pursuit didn’t affect later-planted cover crops at a site in a University of Wisconsin trial.

“The next year, they fried them,” says Johnson.