Nearly 800 comments submitted to EPA on its dicamba ecological and human health risk assessments split widely on the herbicide’s value to American agriculture.

Broadly speaking, comments broke down into two groups: Many of the commenters, including state agriculture agencies and USDA, said the herbicide is a valuable tool whose damage to non-dicamba tolerant crops and other vegetation has been overstated. And the chemical can be used safely, those commenters said. 

On the other side were those, including farmers and seed dealers, who said off-target damage is well-documented and that it’s time for EPA to pull the registration or at least severely restrict its use.

The agency plans to issue a draft decision next year on the registration, which is currently good through 2025.

EPA released the risk assessments in August, finding that despite restrictions on dicamba use required in 2021, EPA received nearly 3,500 incident reports about off-target damage during the growing season. “These incidents occurred even though EPA implemented new control measures in the 2020 registration decision and were reported by various stakeholders including states, academic researchers, media, impacted individuals, and companies,” EPA’s assessment said.

The damage was reported to non-DT soybeans and numerous other crops as well as a wide variety of non-target plants in non-crop areas, including residences, parks, and wildlife refuges. 

In its ecological analysis, EPA found a “risk concern for terrestrial plants for all currently labeled uses of dicamba” and a “potential acute risk concern for birds” for all registered uses of dicamba.

The Agriculture Department, however, said the agency’s use of the maximum labeled application rate for each crop use pattern “can sometimes lead to overly conservative exposure and risk estimates.”

In most cases, average application rates as reported by the National Agricultural Statistics Service and the Agricultural Resources Management Survey “were lower than the modeled maximum labeled application rates,” USDA said. “The only average single application rates that are close to the labeled maxima are those for dicamba-tolerant (DT) cotton and soybean. However, the average number of applications per year for the DT crops is [less than] 2, much lower than the maximum allowed of 4.”

CropLife America, the trade association for pesticide manufacturers, questioned the validity of a report EPA used to support its assertion that dicamba has likely caused “wide-area” damage, which EPA defined in its assessment as “10’s to 100’s of acres per incident.” 

The group also questioned EPA’s assumption that there were many more unreported incidents. EPA said that “despite the large number of incidents reported to EPA,” information available from USDA “indicates that both the number of dicamba incidents and their geographic extent are substantially greater than indicated by registrants’ 6(a)(2) reporting and incidents reported by others to the agency.”

But CropLife said EPA was wrongly extrapolating from a 2018 ARMS survey. “These ARMS survey responses are self-reported and unverified,” CropLife said. “Growers may not be trained to identify dicamba symptomology and able to distinguish it from other markers of plant stress. A level of expertise is necessary to distinguish dicamba-related cupping from other symptomology from other causes.”

Many commenters simply said they wanted to be able to continue using dicamba products. “Dicamba is [a] herbicide that works!” Texas cotton grower Nolan Smith said. “We farm around 12,000 acres of cotton. We use pre herbicides plus dicamba as a post.” With resistant weeds growing in strength and numbers, “we cannot afford to lose dicamba as a mode of action.”

But some farmers and seed dealers said they want EPA to either not re-register dicamba or move up its cutoff date from June 30.

“Attached is a list of farmers which represent 29,933 acres of damaged soybeans from dicamba,” said John Brockmueller of Dakota Seed and Service in Wakonda, South Dakota. “We are asking that you move the final date to spray dicamba to June 1, as this will eliminate or greatly reduce the risk from volatilization.”

“This date needs to be moved because it is forcing farmers to plant dicamba resistant crops, but still leaves trees, gardens, orchards, and the health risk because we are breathing these vapors,” Brockmueller said.

“I think you need to remove dicamba completely,” Iowa seed merchant Henry Merschman of Merschman Seeds said. “I have personally seen thousands of acres damaged by dicamba. Crops, trees, gardens, it is very bad.”

Fellow Iowa seed company CEO Harry Stine had a terse comment: “Our extensive soybean plant breeding program has suffered significant damage from dicamba for years. This has been a huge loss for American agriculture. The cut-off date for all applications of dicamba should be June 1st.” The current federal cutoff is June 30, but some states have instituted earlier cutoffs. 

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“Use of any form of dicamba during the growing season needs to end,” Iowa grower Aaron Easton said. Through direct drift and volatilization, he said his soybeans “have been significantly impacted the last six years by neighbors using dicamba on both their corn and soybeans,” “I have had several instances of obvious yield loss, backed up by insurance adjusters, along with troubles with late season weeds because my soybeans are hurt so bad they won't canopy.” He said mitigation requirements haven’t helped.

A grower, seed salesman and Jasper County, Indiana, Farm Bureau member said in-season use needs to be prohibited. 

“It is my belief that we need to further restrict the use of dicamba and dicamba-based derivatives to a burn-down only (effectively pre-planting or at a minimum before any crops have emerged),” said the comment, signed “Concerned farmers in Jasper County, Indiana.”

The comment said farmers in the county “experienced widespread off target movement of applications of dicamba-based products in our area, both in corn and in soybeans, resulting in crop injury to non-dicamba-resistant soybeans, ornamentals, and high value specialty crops.” About 1,000 acres were affected, the comment said.

The Center for Food Safety, a legal advocacy group long critical of agricultural biotechnology, said EPA failed to update its predictive capabilities to deal with the effects of dicamba volatilization. 

“EPA’s two sets of test guidelines for lab and field volatility both prescribe application of the pesticide to soil, because they were designed to test the volatility of soil fumigants and perhaps other soil-applied pesticides, and neither makes any reference to vapor drift injury to plants,” CFS said, citing a study by University of Tennessee weed scientists that showed “dicamba emissions were over 300% greater when the herbicide was applied to green plants vs. other surfaces.”

CFS also said EPA has failed “to scale up estimates of the distance dicamba drift travels off-field, in the form of either spray or vapor, from field-trial to commercial production scale. XtendiMax volatility was originally assessed based primarily on flux data gleaned from two tiny field trials of 3.4 and 9.6 acres.”

Volatilization is a huge problem, Iowa farmer Joe Bahe commented. “Dicamba is akin to the Tasmanian Devil – give it little heat [and] it goes nuts. Apply in heat, it goes nuts. Add salt (AMS) to it, it goes nuts. Combine the wind, the heat and a bunch of applicators spraying at the same time, this devil will leave its mark for MILES.” 

“I'm fine with dicamba, as long as you can keep it to respect a fence line,” he said. “The problem is you can't and you won't.”

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