The Iowa lawmaker’s proposal also threatens family farmers, rural communities, and food safety.

Missouri farmer Wes Shoemyer felt a huge relief last October when his state passed legislation restricting the application of the weed killer dicamba, which has a tendency to vaporize and drift, harming plants not genetically modified to resist it.

Before the new regulations, a neighbor’s application of the pesticide wafted onto Shoemyer’s property and turned the edges of his soybean plants brown and yellow. Further south, another case of dicamba drift caused millions of dollars of damage to the largest orchard in the state.

Shoemyer worries, however, that the state law protecting his crops from the herbicide will come under threat if legislation that Representative Steve King (R-Iowa) has introduced for inclusion in the 2018 Farm Bill gains traction in Congress.