Weather extremes, weed adaptability and low crop prices challenged Iowa farmer Jim Legvold's long-term plan of corn-soybean herbicides, residual herbicides and rotated modes of action.

Legvold “had problems this year just like everyone else,” observes Mike Owen, Iowa State University weed scientist. “Weeds adapt better to environmental conditions better than crops do. Sometimes you can’t beat Mother Nature.”

http://cornandsoybeandigest.com/crop-chemicals/8-tips-successful-weed-control