"When Tom Barber, a scientist at the University of Arkansas who studies weeds, drives the country roads of eastern Arkansas this summer, his trained eye can spot the damage: soybean leaves contorted into cup-like shapes.

He's seeing it in field after field. Similar damage is turning up in Tennessee and in the "boot-heel" region of Missouri. Tens of thousands of acres are affected.

This is no natural phenomenon of weather or disease. It's almost certainly the result of a crime. The disfigured leaves are evidence that a neighboring farmer sprayed a herbicide called dicamba, probably in violation of the law.

Dicamba has been around for decades, and it is notorious for a couple of things: It vaporizes quickly and blows with the wind. And it's especially toxic to soybeans, even at ridiculously low concentrations."

Dan Charles reports for NPR August 1, 2016. [2]