In the battle against herbicide-resistant weeds, farmers are increasingly eager to add non-chemical control methods to their management toolbox. Impact mills, which destroy weed seeds picked up by a combine, have been shown to kill 70-99% of weed seeds in soybeans, wheat, and other small-statured cropping systems. And a recent Weed Science study from the University of Illinois shows even seeds that appear unscathed after impact milling don't germinate the following spring.