While chemists have done most of the heavy lifting in agriculture’s battle with weeds since World War II, electrical and mechanical engineers are increasingly supporting the fight with innovations to make herbicides more efficient, and in some cases, bypass chemistry altogether.

Throughout history, mechanical tillage provided the most effective method to separate the crop from the tares. Fighting weeds was simple, but hoeing and cultivating were wearisome, and quietly contributed mightily to worn-out farms, as disturbed, bare topsoil washed or blew away. The degradation of the soil was accepted as part of doing business.

By the middle of the 20th Century, however, chemistry provided some of the first compounds — namely 2,4-D — to kill broadleaf weeds with a spray. Killing weeds got easier, but as recent history has proven, keeping farm fields free of weeds began to get a lot more complex.

“Nobody likes complex,” says University of Missouri weed specialist Kevin Bradley, “but weed control is going to continue to get more complex as we move forward. We’re faced with implementing more integrated approaches to weed management. It’s not that I dislike herbicides, since they are still going to be a fundamental part of the way we do weed control, but I’ve seen effective herbicides quickly fail due to resistance.”

Bradley says the complexity likely will continue to demand agronomic weed management like conservation tillage methods that do not disturb the soil and the use of cover crops to suppress weeds, as well as technology to selectively target…