dicamba drift soybeans

Soybeans in southeast Missouri show cupping leaves, a sign of dicamba drift damage.

Some thought this year would be different.

Last year, when illegal usage of the drift-prone herbicide dicamba was blamed for widespread crop damage across southeastern Missouri and other states — and is even suspected of triggering deadly feuds between farmers — many expressed hope that the problem would diminish in future growing seasons, with proper forms of the herbicide gaining approval for use on crops engineered to tolerate the spray.

But that may have been wishful thinking, if the recent explosion of 242 cases of alleged dicamba misuse in Arkansas is any indication. Amid the snowballing number of complaints in the state, the Arkansas State Plant Board proposed an emergency ban of the chemical for in-crop use June 23.

Leading the way with 81 complaints is Mississippi County, Ark., which borders Missouri’s Bootheel, where most of the region’s cases were concentrated last year. Those in the Bootheel, meanwhile, are waiting to see if a similar crisis unfolds once again. The area’s growing season lags a bit behind that in Arkansas, and it wasn’t until late last June that local dicamba complaints began to surface.

But Kevin Bradley, a University of Missouri plant sciences professor who investigated much of last year’s damage, says he’s been fielding complaints of crop injury over the past couple of weeks, while the Missouri Department of Agriculture has received 60 reports of misuse so far, statewide. Last year, more than 120 cases of suspected drift were reported to Missouri officials.

Bradley says continued damage from the herbicide this year would be a predictable consequence of so many farmers converting to dicamba-tolerant soybeans and cotton — many of whom did so to avoid the damage suffered last year.

“It’s concerning but not a surprise,” Bradley said. “We knew that the acreage that gets sprayed with that dicamba product would be dramatically more than it was last year.”

The volatile chemical is sensitive to vaporizing and drifting into nearby fields where nonresistant crop varieties are vulnerable to injury. Last year, much of the damage was believed to have been caused by renegade farmers who illegally sprayed older, highly volatile versions of the chemical on Monsanto’s dicamba-tolerant soybean and cotton, which the company released prior to regulatory approval of the corresponding herbicide.

Though growers were warned not to apply “off-label” or unauthorized forms of dicamba, many appeared to do so to combat weeds that have developed resistance to other herbicides like glyphosate, the active ingredient in Roundup.

This year, newly approved dicamba products from Monsanto and BASF aimed to offer farmers less-volatile alternatives to use with resistant seed varieties. But even those could be triggering at least some of the complaints.

“All the calls I’ve had this year, these are people that are spraying the newly approved products. They’re doing the best they can do,” Bradley said.

He said those calls stem from users of both Monsanto’s product, XtendiMax, and Engenia, the BASF alternative.

Tom Burnham, an Arkansas grower whose farmland stretches across Mississippi County and into Missouri’s Dunklin and Pemiscot counties, estimates that all of his 7,500 acres of LibertyLink soybeans have symptoms of dicamba damage. He calls off-target movement of dicamba the most serious issue he has confronted in more than three decades of farming, and thinks the problem has arisen despite correct application methods by other growers nearby.

“Last year I didn’t have any issues. This year it’s an epidemic,” Burnham said. “These weren’t what I call cowboys using the old versions of dicamba. These were people using the right stuff the right way.”

In Arkansas, only Engenia was approved for use this growing season, after the state declined to authorize Monsanto’s formulation.

“On multiple occasions, Monsanto did not provide a detailed enough explanation about their new product for the Arkansas State Plant Board to approve it for use,” the Arkansas Agriculture Department said following their January decision. Monsanto denied the statement, noting that sufficient data was provided for approval in 33 other states.

University of Arkansas scientists have yet to independently test the volatility of XtendiMax, according to Jason Norsworthy, a professor of weed science at the school. He said that the university has looked at Engenia, though, which BASF reports has been applied to more than 700,000 acres in Arkansas this year.

“It does have reduced volatility,” Norsworthy said. “(But) we can’t say that it’s a nonvolatile form of dicamba.”

The state is investigating the cases of alleged misuse, which can also result from physical drift or other factors related to temperature and conditions at the time of application. BASF, which criticized moves to ban Engenia use this season, reiterated claims that the product is up to 90 percent less volatile than other forms of dicamba, suggesting that instances of drift caused by factors such as wind or improper application techniques can be mistaken for volatility.

Arguing against efforts to ban dicamba in Arkansas, company representatives noted the “vast majority of those using Engenia, here in Arkansas and across the country, are experiencing positive results with no off-target movement.”

Farmers such as Burnham, though, worry the rising complaint totals signal that new dicamba products can’t be used safely, especially on such a large scale.

“I don’t feel that this technology can be successfully used. Our heat, humidity and topography are highly conducive to off-target movement,” Burnham wrote in a letter submitted to Arkansas’ plant board last week.

He argued that rampant drift unfairly influences the choices of non-GMO farmers, estimating that half of the region’s acreage planted in dicamba-resistant crops this year was done by farmers solely aiming to protect themselves from damage. “I feel that the need to plant a technology to protect your crop from off-target movement is tantamount to extortion,” Burnham wrote.

But, even if adopted out of necessity, some farmers converting to the crops expressed relief knowing that episodes of dicamba damage were behind them. And they’re in good company, with Robb Fraley, Monsanto’s executive vice president and chief technology officer, saying that the technology is being adopted in record numbers.

“In the first year the product has been in the marketplace, we’ll be somewhere between 20 and 25 million acres which will make it one of the largest launches we’ve ever had,” Fraley said.

Though Monsanto’s XtendiMax products were already barred from Arkansas and not affected by the state’s proposed ban, Fraley echoed BASF’s argument that the technology is needed by farmers to fight weeds and boost yields.

“The real loser in the decision is the Arkansas farmer,” Fraley said. “In the middle of the cropping season, they’re being disadvantaged.”

Editor's note: The Arkansas State Plant Board voted Friday to propose an emergency ban on in-crop dicamba use. The recommendation still must be reviewed by the Arkansas governor and a state legislative council before it is enacted.