CHAMPAIGN, Ill. (AP) — For the third straight year, a volatile pesticide is damaging crops across the Midwest and South, despite federal and state efforts to lessen the drift.

Since 2017, farmers have sprayed an increasing amount of the weed killer, called dicamba, on soybean and cotton crops genetically engineered by agribusiness company Monsanto to withstand being sprayed by the herbicide.

But each year, dicamba has drifted off-target and damaged millions of acres of non-resistant soybeans, specialty crops and other plants.

In fact, farmers in Illinois, the nation's leading soybean producing...