Larry Martin in Illinois says he’s never seen anything like it in his 35 years of farming. Arkansas soybean grower Joe McLemore says he faces the loss of his life savings.

They’re among farmers across the U.S. suffering from a pesticide “drifting” across from neighboring fields onto their crops, leaving behind a trail of damage. Although not a new problem, it’s re-emerged with a vengeance this year. At least 2.5 million acres (1 million hectares) have been damaged in this growing season through mid-July, according to estimates from Kevin Bradley, a professor of plant sciences at the University of Missouri.

Dicamba, the offending herbicide, is produced by seed and crop-chemical giants Monsanto Co., DuPont Co. and BASF SE. It’s been around for decades, but in recent years it gained a new lease of life after the companies developed new dicamba-resistant soybean and cotton seeds, allowing farmers to spray crops later in the growing process.

Dicamba is fine if you’re growing those genetically modified varieties, but not if you’re cultivating others and the chemical wafts over from another farm. The situation is so bad that states including Missouri, Arkansas, and Tennessee have placed restrictions on dicamba use at various times during the summer.

Martin, a third-generation farmer, says an 80-acre soybean field of his has been damaged by dicamba. McLemore, who started out on his own eight years ago, after two decades working on someone else’s farm, says 800 of his 1,026 acres of soybeans have suffered damage.

Stunted, Wrinkled

“I’m not really trying to whine or anything, but it’s my life savings on the line every year,” he said by phone.

McLemore is among a group of growers that have filed a lawsuit in a federal court in Missouri against BASF, Dupont and Monsanto for compensation. Monsanto spokeswoman Christi Dixon said the suit is without merit, while BASF spokeswoman Odessa Hines said it’s reviewing the claim. Dupont spokeswoman Laura Svec said the company hasn’t seen the lawsuit and so can’t comment on it.

Non-resistant crops are left stunted with wrinkled leaves after coming into contact with dicamba. Frustratingly, there’s no way to gauge the impact of yield until the fall harvest, farmers and researchers say. And it’s not always clear where the chemical might have come from McLemore says that, in his case, he can’t be sure. That leaves farmers angry but also unsure whether to blame neighbors or herbicide manufacturers, said Aaron Hager, a weed scientist at the University of Illinois.

Farmers planted 20 million acres of dicamba-resistant soybeans and 5 million acres for cotton this year, executives at St. Louis-based Monsanto said in a telephone interview Monday. The company attributes the drifting problem to farmers using illegal, off-label products that are more volatile — and thus more prone to drift — than the latest versions of dicamba. They may also be cleaning or using their spraying equipment incorrectly, or applying dicamba when it’s windy, said Robb Fraley, executive vice president and chief technology officer.

Monsanto, which is being acquired by Germany’s Bayer AG, says employees are out in the fields talking to farmers about the problem. Fraley said farmers want better weed-control tools, such as dicamba product, and that the company will learn lessons from what’s happened this season. “There’s always a few challenges in launching new technology,” he said.

Germany’s BASF referred questions on dicamba to a recording of a July 19 media briefing that cited possible explanations for drifting similar to those outlined by Monsanto.

“This year thousands of growers have used these products properly and successfully meeting their challenges with resistant weeds and productivity,” said Svec at DuPont, which has a supply agreement with Monsanto for the herbicide.

The Environmental Protection Agency says it’s reviewing the situation.

“EPA is very concerned about the recent reports of crop damage related to the use of dicamba in Missouri, Arkansas and other states,” an EPA spokesperson said in an emailed statement. “We are working with the states and the registrants to better understand the issue. We are reviewing the current use restrictions on the labels for these dicamba formulations in light of the incidents that have been reported this year.”

While farmers typically look to federal crop insurance for a myriad of issues, problems with dicamba aren’t covered, according to the Risk Management Agency. Country Financial, a farm insurer, based in Bloomington, Illinois, has seen an increase in the number of dicamba-related inquiries, said company spokeswoman Alexandrea Williams. Martin, the Illinois farmer, says he’s not confident his insurance coverage will pay out.

“This is the craziest thing I’ve ever seen,” he said in a telephone interview. “You know you’re going to have a loss of income.”