EPA aims to reapprove controversial herbicide. State regulators worry the label is too confusing

The Trump administration wants to allow soybean and cotton farmers to use a controversial weedkiller once again. Dicamba is known to drift off of fields where it’s applied and damage neighboring crops.

Dicamba can stunt the growth of or kill plants that haven’t been genetically modified to resist it. Dicamba is more volatile than other herbicides — which means it can turn airborne more easily and affect plants farther away.

Just one year after the Environmental Protection Agency first approved dicamba for use, complaints about the weedkiller shot up across the country.

The EPA has changed dicamba’s restrictions several times to try to address the issue. Courts ordered the EPA to revoke its approval of dicamba twice following lawsuits.

Bill Freese is with the sustainable agriculture nonprofit Center for Food Safety. He said dicamba can damage non-resistant soybeans but also fruit crops and trees.

Freese said one of the reasons dicamba was banned in the past is because it can tear rural communities apart — and that’s something the Trump administration needs to consider.

“Farmers who are spraying dicamba cause injury to their neighbors and sometimes lifelong friendships have been, you know, disrupted," he said.

Sarah Caffrey is the pesticide administrator for the Office of Indiana State Chemist. She said because the label has changed so many times, it's not clear what solutions to the dicamba problem have actually worked.

One thing is for sure, Caffrey said dicamba has always had complicated instructions.

“This is a label that is very hard to follow. I don’t think the proposed language is making it any easier," she said.

Among other things, the proposed new label doesn’t specify dates and times when farmers aren’t allowed to apply dicamba.

Instead it relies on farmers to track the weather forecast and know when a temperature inversion is happening. That’s where cooler air is near the ground and warmer air is on top — which can trap pollution.

Dicamba is more volatile at higher temperatures. Caffrey said when the federal government set cutoff dates for dicamba in the past, they usually didn’t pick dates when the temperature was likely to be above 85 degrees Fahrenheit.

With this proposed label, farmers could apply dicamba between 85 and 94 degrees — but dicamba would be the only pesticide allowed in the application tank.

Indiana could still decide to set its own cutoff dates through what’s called a “collateral label” — a separate booklet that accompanies the herbicide.

Madelyn Derks is the director of government relations for the American Soybean Association.

“We are excited to see a new label. Access to post-emergent weed control options are really important, especially since weeds can steal more than 50 percent of a soybean crop yield,” she said.

But Derks said soybean farmers are unsure about what putting the label into practice will look like on their farms.

The public has until Sept. 6 to comment on the dicamba reregistration.

This story has been updated.

Rebecca is our energy and environment reporter. Contact her at rthiele@iu.edu or on Signal at IPBenvironment.01. Follow her on Twitter at @beckythiele.