650,000 acres of soybeans damaged by dicamba this summer, state estimates

Soybeans in a Mississippi County field show signs of herbicide damage in this photo taken in June 2018.
Soybeans in a Mississippi County field show signs of herbicide damage in this photo taken in June 2018.

An estimated 650,000 acres of soybeans have been damaged by dicamba in Arkansas this summer and dicamba complaints filed with the state have increased at a clip not seen since 2017.

The estimate by the University of Arkansas System's Division of Agriculture is based on the collective experiences of extension agents, weed scientists and crop consultants who have been inspecting soybean fields across the state's eastern third the past few weeks. About 400,000 of the affected acres are in Arkansas, Prairie, Poinsett, Cross and St. Francis counties, the division said.

Of the state's estimated 3 million acres of soybeans, about 1 million are of varieties that aren't tolerant of the herbicide. The other 2 million acres are soybeans genetically modified by Monsanto to be tolerant of dicamba and released commercially in 2016 as part of its Xtend crop system. The 650,000 damaged acres equate to 1,106 square miles, more than Union County, the state's largest county at 1,039 square miles.

Arkansas farmers this year had a June 30 cutoff on spraying federally licensed dicamba formulations across the top of their dicamba-tolerant soybeans and cotton. By calendar days, it was their longest legal spray season yet for the herbicide, although heavy and persistent rainfall in late May and early June disrupted spray schedules.

Sen. Ron Caldwell, R-Wynne, chairman of the Senate Committee on Agriculture Forestry and Economic Development, on Wednesday organized a dicamba-damage tour consisting of a half dozen stops at farms along a 100-mile loop from Stutttgart south to DeWitt, east to Holly Grove and Marianna and north to Forrest City and Wynne.

Some 50 farmers and others were at the stops in Stuttgart and Wynne; there were fewer participants in the caravan tour as it progressed east.

"At every stop we saw damage at varying levels," said Caldwell, whose Senate committee will meet jointly with its House counterpart today in Hot Springs, with dicamba damage on the committees' agenda.

"Some had just curled leaves that will probably grow out of the damage," Caldwell said. "Some plants will have reduced yields. Some won't live. We relied on weed scientists and agronomists, not the farmers, who could point out that this was damage from dicamba, not some other source, and explain to the layperson what plants could have reduced yields and what plants wouldn't live. We wanted qualified people there to answer questions, folks who knew the science. I wanted scientific answers, not emotional ones."

The state Plant Board, a division of the Department of Agriculture, in December initially retained a May 25 cutoff set for the 2019 and 2020 crop seasons but, with a change in membership, voted three months later for June 30 cutoff. The progress of a lawsuit in Pulaski County Circuit Court challenging how the board complied with state law in making that reversal has been halted by the Arkansas Supreme Court.

In another ruling this spring unrelated to the board's reversal of the cutoff, the Supreme Court ordered removal of nine of the Plant Board's 16 members with voting privileges, saying the General Assembly had unconstitutionally allowed trade groups to select the members.

The board hasn't met since that ruling because of its inability to legally muster a quorum. A state law revamping the board's composition takes effect July 28, but the board's return to full membership might not happen until late summer or early fall. The new law permits the trade groups to nominate Plant Board members, with the governor then making selections subject to confirmation by the Senate.


As of noon Friday, 292 complaints of possible dicamba damage had been filed with the Plant Board, with all but about 30 filed since July 1. Another 126 complaints filed since January don't specify a particular pesticide or herbicide.

Farmers and others filed 1,014 dicamba-specific complaints in 2017, when the Plant Board adopted a mid-season emergency ban. Investigations confirmed dicamba as the cause of damage in 900 cases. About 200 dicamba complaints were filed in each of the 2018, 2019 and 2020 crop seasons, with dicamba confirmed in 70% of those cases.

The coronavirus pandemic, which prevented in-person board meetings last year, and the Supreme Court's ruling on the board's membership have stymied the board's work on 2019 and 2020 dicamba violations -- with some violations eligible for fines of up to $25,000.

Arkansas Secretary of Agriculture Wes Ward, who attended last week's farm tour, declined to compare damage in past years with that in 2021, citing facts that vary over the years.

"We don't know the end result [of complaints]," Ward said by telephone Wednesday at the end of the tour. "I suspect that number will continue to go up but, hopefully, we are nearing the end of that. We hope people will follow the rules and not apply [dicamba]."

A surge of complaints is coming from counties that didn't have many dicamba problems in the previous four years of the state's saga with the herbicide.

Arkansas County had four complaints from 2017-20 but 60 as of Friday, the most in the state. Complaints from Woodruff County numbered 26 over four crop seasons, but 24 have been registered so far this year. Fourteen complaints have been filed from Jackson County this year, compared with five from 2017-20.

Meanwhile, the number of complaints has been sharply reduced this year from counties that had major problems with dicamba in past years.

Mississippi County had 261 complaints in 2017 and about 150 from 2018-20 but just two so far this year. Complaints from Crittenden County have dropped from 271 from 2017-20 to five this year; complaints in Craighead County have dropped from the four-year total of 141 to 14.

That change, according to weed scientists and others, is partly because farmers in counties such as Mississippi, Crittenden and Craighead are almost exclusively planting dicamba-tolerant crops and spraying dicamba, reducing by simple math the planting of crops susceptible to the herbicide.

The widespread use of dicamba, critics say, is loading the atmosphere, posing a bigger threat each year to other crops and vegetation not tolerant of the herbicide. Counties west of Crowley's Ridge, usually a natural barrier to dicamba's spread from Delta counties, are seeing more complaints this year.

Research plots at five UA research stations in Mississippi, Lee, Arkansas, St. Francis and Desha counties have sustained damage this summer. Depending on the aim of the research project, some of those plots have been rendered useless. While a weed study might still be salvageable, for example, a yield study wouldn't be because dicamba exposure would ruin any controls or baselines.

Most damage has been attributed to dicamba's volatility -- or tendency to lift off plants as a vapor hours or days after application and move miles away to susceptible crops and vegetation. Weed scientists say it's almost impossible to determine the source in those cases. The source of physical drift, which occurs as the herbicide is applied, is more easily traced, as it leaves a distinct pattern through affected fields.

It generally takes a couple of weeks for dicamba damage to appear on soybeans and then, varying times for a farmer to spot that damage, resulting in a timeline that means officials expect complaints to continue into late July or early August.

The UA estimate on acres damaged involve only soybeans, not cotton or other commercial crops, or possible damage to backyard gardens, trees and ornamental shrubs on private property or vegetation on public lands such as right-of-ways, city and state parks and wildlife management areas.

Monsanto genetically modified soybeans and cotton to be tolerant of dicamba as "super weeds," including pigweed in Arkansas, developed resistance to glyphosate and other herbicides. Monsanto in 2017 released new dicamba formulations that were supposed to be less susceptible to off-target movement.

While not specifically addressing alleged dicamba problems in Arkansas, a Bayer spokesman said Friday the company stands by its Xtend crop system. "Based on our conversations with growers and our observations so far this season, we believe our customers are having a very successful season with XtendiMax herbicide," the spokesman said, adding that the company believed new rules by the Environmental Protection Agency improved the effectiveness of the crop system.

Officials at Corteva Agriscience, developers of Enlist varieties of soybeans that have sustained damage this season, didn't respond to requests for comment.

Dicamba manufacturers said in 2017 there would be fewer problems as farmers received more training and got more experience with the herbicide.


"I've been working in several counties that had some problems in years past but now have landscape damage," Tommy Butts, a UA weed scientist, said, referring to widespread damage across multiple fields in a localized area and stretching from one end of a field to the other.

While Butts has spent time in fields across the Delta, most of the past couple of weeks has been spent in Arkansas County.

"They've had soybean injury across that entire county, and it's fairly severe injury," Butts said. "I've walked fields from around Stuttgart, to south of DeWitt and over to St. Charles and Crocketts Bluff. I've seen injury anywhere and everywhere in Arkansas County."

Soybean production in Arkansas County generally is opposite the state average, with about 70% non-Xtend, or crops not tolerant of dicamba, and 30% Xtend, Butts said.

Yield loss is difficult to project and really won't be known until harvest this fall, Butts said, citing several factors, including growth stage of the soybeans when exposed to dicamba and the number of times exposed.

While yield losses have often been downplayed by dicamba-use advocates, Bayer last year agreed to settle class-action "legacy" lawsuits filed against Monsanto before Bayer bought the latter company in 2018 for $63 billion. Without admitting wrongdoing, Bayer set aside $300 million to pay farmers for soybean losses from 2015-20 through an on-going claims process.

Farmers and custom applicators who spray dicamba now are required by the EPA to use an approved "volatility reducing agent" in their dicamba tank mixes and keep records of the agents' use. The agents are supposed to reduce dicamba's volatility by stabilizing pH levels in the tank mix; the lower the pH the more volatile dicamba becomes.

The EPA said last fall it was 90% certain the new agents -- produced by makers of lower-volatility dicamba formulations -- would reduce damage.

"Apparently the so-called volatility reduction agents are working about as well as the low-volatility dicamba formulations, which is to say they aren't working well at all," said Ford Baldwin, a crop and weed consultant and retired UA weed scientist who warned the Plant Board in 2015 of problems that would be caused by the Xtend seed-and-dicamba crop system.

"We've seen this train wreck before over the last six years," Baldwin said. "The EPA, the Plant Board and Department of Agriculture are on the wrong side of the science."

Dicamba manufacturers refused to allow independent testing of the volatility-reducing agents just as they prohibited independent testing years ago of the volatility of the low-volatility dicamba formulations, Baldwin said.

Now that the volatility reduction agents are commercially available, weed scientists in Arkansas and other states are testing the agents for their effectiveness.

Baldwin said the agents reduce dicamba's volatility in a tank mix but, considering widespread crop damage this season, they apparently don't reduce its volatility after application, when some dicamba converts to an acid on plants and soil.

"The acid form is volatile, and that is a problem that hasn't been solved and might not ever be solved," Baldwin said. "It's a product that never should have been registered for the use we're using it for. By the end of the season there won't be a non-Xtend bean that won't be hit and there won't be any help for those who want to grow commercial vegetables or raise a garden or who don't want their trees and shrubs damaged."

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