Two years ago, corn harvest was a bear. And now, with the 2011 crop right around the corner, that nightmarish 2009 harvest season isn't going away yet.

That's because a problem that the '09 harvest spawned in 2010 will remain an issue again this year. Volunteer corn was "quite impressive" last year in a lot of locations, and it's expected to be a consideration for weed management this year again, says University of Illinois crop scientist Aaron Hager.

"Volunteer corn will likely be a weed management consideration again in 2011, but volunteer corn densities are likely to be much lower than was experienced in 2010," Hager says. "Our sense is that more acres of the 2011 soybean crop are scheduled to be treated with a soil-residual herbicide than were treated in 2010."

Treatment will be best achieved, Hager says, by soil-residual herbicides in "timely postemergence applications before weed interference reduces crop yield potential" rather than preemerge applications. "The high market prices for soybean, coupled with the increasing occurrence of herbicide-resistant weeds, suggest that soil-residual herbicides are likely to become staples of more integrated weed management systems," he says.

On top of that, herbicide-resistant waterhemp, giant ragweed and Palmer amaranth are others that could potentially cause problems for farmers this year in the Corn Belt, Hager adds.

"Herbicide-resistant weeds are poised to become an even larger weed management challenge in 2011," he says. "These are by no means the entire waterfront of challenges weeds could impose during 2011, but they do represent issues expected to be widespread across much of [Illinois]."