EPA re-registration moves dicamba forward

It gives farmers the green light to apply dicamba from 2021 to 2025, but legal challenges loom.

There’s something for everyone in the October 27 decision by the Environmental Protection Agency (EPA) to re-register dicamba formulations for dicamba-tolerant soybeans and cotton.

It’s good news for farmers who use the technology and those who make it, which includes BASF (Engenia), Bayer Crop Science (XtendiMax with VaporGrip Technology), and Syngenta (Tavium Plus VaporGrip Technology). EPA’s re-registration will enable these firms to sell these formulations to farmers for the 2021 to 2025 growing seasons. 

It’s a strong registration that will help reduce challenges – such as off-target movmenet – that the technology has encountered in the past, says Alex Zenteno, Bayer dicamba product manager.


“We thank EPA for the many steps and time invested in coming to this decision to reregister a product relied upon by many soy growers,” said Bill Gordon, a Worthington, Minnesota, soybean farmer and president of the American Soybean Association, in a news release.

Bayer is also the registrant for the dicamba formulation that Corteva Agriscience had previously marketed as DuPont FeXapan herbicide with VaporGrip Technology. Now that the EPA has registered Bayer’s dicamba formulation, Corteva will be able to apply for federal registration of FeXapan, say Corteva officials. 

If you’re a critic of the technology, EPA’s decision is not good news. “Dicamba is a disaster,” wrote John Zuhlke in an email. He’s the owner of Little Shire Farms, an Aurora, South Dakota, farm that at one point raised 600 types of vegetables. Zuhlke says off-target dicamba applied since 2017 prompted Little Shire Farms to scale back growing vegetables and switch to honey production.

There may be hope for Zuhlke and others who oppose the technology. “I really do think that the Ninth Circuit (U.S. Court of Appeals for the Ninth Circuit that vacated registrations for XtendiMax, Engenia, and FeXapan on June 3, 2020) will find that the EPA rushed to a conclusion to appease corporate ag interests with little science to back the decision,” he writes. 

That’s a good possibility, says Charles Benbrook, president of Benbrook Consulting Services, who has provided consulting services for the organic industry and chemical companies.
“It is highly likely that the Ninth Circuit will be asked to revisit its earlier (June 3) order,” he says. 

What’s Changed

Several changes for dicamba are on tap due to the re-registration. They include: 


A national cutoff date of June 30 on soybeans and July 30 for cotton for all over-the-top uses of dicamba. This differs from the 2018 label prohibited  over-the-top (OTT) application of dicamba on soybeans 45 days after planting.

Slight differences exist in cutoff wording between chemistries. Bob Hartzler, Iowa State University Extension weed specialist, notes that XtendiMax application is prohibited after R1, even before the June 30 cutoff date. If the R1 stage has not been reached, XtendiMax can be applied up to June 30. With Tavium, application is allowed through V4, but not after June 30. There is no mention of growth stage with Engenia, he adds. This may enable Engenia to be applied later than Xtendimax in some cases, but not after June 30, he says. 

“The cutoff date is easy to understand,” says Zenteno. “It’s very clear when that application window ends.” 

The date cutoff does prevent dicamba from being applied into July, when the bulk of off-target complaints surfaced in Minnesota in 2017.

  
“The data was clear in 2017 that (off-target) incidents increase after June 20 and especially in July,” said Jeff Gunsolus, who served as University of Minnesota Extension weed specialist that year before retiring in 2019. 

A downside, though, is that weeds like waterhemp can still poke through after June 30 and threaten yield potential. 

“I think everyone has to understand that the cutoff date isn’t as much about the (dicamba-tolerant) beans that are in the field, as much as it is about the neighboring crops and the sensitivity of adjacent fields,” says Jamie Leifker, WinField United vice president of agronomy and product development. Thus, farmers will have to form management plans taking this into account, he adds. 

Mandated use of a pH buffering agent to be mixed prior to all dicamba products being applied. Adjuvants like these reduce acid content of tank mixes by pushing pH above 5 (acid content increases as a solution moves downward on the 0-to-14 pH scale). The higher the acid content, the more prone a herbicide is to volatize and move off target.  


Bayer’s product is VaporGrip Xtra Agent. 

BASF plans to launch its Sentris buffering technology for the 2021 growing season. It’s a liquid buffering agent that when added to a dicamba spray solution will increase and stabilize the solution pH and reduce the potential for volatility, say BASF officials. 

“This will become part of the system, and farmers will have to factor it in as part of the cost and operational structure,” says Leifker. 


Volatility is only part of the reason that dicamba can go off-target, though. Physical drift also accounts for off-target dicamba, he says. 

“If you’re not using the proper additives and nozzles and also spraying in the right conditions – which can change at the snap of a finger – while making an application, drift can occur,” says Leifker. He says that using proper technologies and spraying under recommended conditions may not reduce drift 100%, but WinField United strategies have reduced driftable fines by over 60% lower than EPA recommendation, he says.

One drift-reducing adjuvant WinField United sells to prevent off-target movement is InterLock. “It’s one of the most dependable drift-reducing agents on the market,” Leifker says. 

Increased the required downwind buffer from 110 feet to 240 feet, with an increased buffer of 310 feet in counties where endangered species exist.


“Growers will continue to have to manage the buffer distances, just like they did in the past,” says Zenteno. “It now is an increased distance.”

In the case of XtendiMax, the re-registration process also will feature an easier-to-follow label, says Zenteno. “We’ve added an application checklist overview in the beginning of the label that clearly outlines the summary of the key requirements,” she says. 


General Restrictions

These general restrictions for dicamba used in dicamba-tolerant soybeans still apply, says Hartzler. 

  • Apply only one hour after sunrise through two hours before sunset.
  • Apply when wind speed at boom height is between 3 and 10 mph. (In Iowa, Hardin County and several counties in northeast Iowa are affected by this).
  • Do not apply during temperature inversions.
  • Do not apply product if sensitive crops or certain plants are in an adjacent downwind field.
  • Do not apply if rain expected in the next 48 hours may result in runoff.
  • Maximum boom height of 24 inches; maximum ground speed of 15 mph.
  • Dicamba0specific training still required.
  • 57-foot omnidirectional buffer required in counties with endangered species.

State Restrictions


States were able to enact restrictions on the federal label with previous registrations. The Minnesota Department of Agriculture (MDA) adopted two 24(c) restrictions to the federal label starting in 2018: 

  • No dicamba applications in dicamba-tolerant soybeans after June 20. 
  • No dicamba applications in dicamba-tolerant soybeans if the daily high temperature is forecast to be over 85°F.

Under FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act, there is a specific process under its Section 24 (a) for states that wish to restrict the federal label, says Alex Dunn, assistant administrator for EPA’s Office of Chemical Safety and Pollution Prevention. Conversely, FIFRA’s Section 24 (c) provides a specific process for states to expand the federal label.

However, states wishing to enact more restrictions on the federal label may have to go a different route than Section 24 (a) this time, says Zenteno. 

“EPA has made some public statements about not allowing that,” she says. “There are other measures that the states could use as far as trying to make the label (more) restrictive. I think for now, we just need to give states the time to review the new label.” Ultimately, she adds it will fall on EPA to give guidance after states have reviewed the label, she adds.

That’s something the MDA says it will do, according to a statement from Joshua Stamper, director of MDA’s pesticide and fertilizer management division. 

“Over the next several days the Minnesota Department of Agriculture (MDA) will be evaluating EPA’s decision to reregister these products with additional restrictions. The MDA intends to make an announcement by the end of the year regarding use of these products in Minnesota so farmers have time to work with their agronomists and seed dealers and make a plan for the 2021 growing season.”

Application Timing

Some University weed scientists, such as Hartzler, have recommended dicamba be used only on a preemergence basis. This would reduce the risk of off-target dicamba hitting neighboring non-dicamba-tolerant soybeans in later growth stages, he says. 

Overall, though, XtendiMax has worked well as an over-the-top herbicide, says Zenteno. 

“Even though there have been some challenges, I think overall when growers use the product in the way that we’ve set up the label, they’ve been incredibly happy and satisfied with the results they’ve gotten related to weed control.”

She says many farmers apply XtendiMax in early soybean growth stages — such as early postemergence — when weeds are easiest to control at a 4-inch or below height. 

“Growers who are more comfortable with that early application timing still see great benefits,” she says. “It’s just going to depend on each grower and what makes them feel comfortable and ultimately how they want to use the product. The added measures that are on this label should allow for the continued success.”

Syngenta’s Tavium follows the lead for early application. It’s a premix of what Syngenta says is a low-volatility dicamba formulation and S-metolachlor (Dual Magnum, Group 15) herbicides. Tavium can be applied though the V4 growth stage of soybeans. 

Resistance management via teaming a preemergence product like S-metolachlor with dicamba was the driving factor in developing Tavium, says Vern Hawkins, president of Syngenta Crop Protection.

“Certainly, taking us out of the over-the-top area did reduce the (off-target) risk, but we wouldn’t have applied the product that late in any case.” 

Still, there was a corollary benefit of reduced off-target exposure, he says. 

BASF is also shifting focus to earlier applications with an anticipated launch of Engenia Prime (Engenia and Zidua, Group 15), pending regulatory approval. 

“This new product will emphasize the importance of early timing, when weeds are only 2 or 3 or 4 inches tall,” says Scott Kay, BASF vice president of U.S. crop protection.  

Legal Challenges

Legal challenges remain. “Rather than evaluating the significant costs of dicamba drift as the 9th Circuit told them the law required, EPA rushed re-approval as a political prop just before the election, sentencing farmers and the environment to another five years of unacceptable damage,” said George Kimbrell, legal director at Center for Food Safety, in a news release. “We will most certainly challenge these unlawful approvals.”

The Center for Food Safety was one of the four groups that filed a lawsuit that led to the June 3 Court decision that vacated the EPA’s 2018 conditional registration of XtendiMax, Engenia, and FeXapan. 

The coming presidential election may also influence matters. If former vice president Joe Biden wins, his EPA and Department of Justice may not defend the 2020 registration if it once again goes before the U.S. Court of Appeals for the Ninth Circuit, says Benbrook. If that happens, it will be up to manufacturers to defend the registration, he adds.

If the Court rules against the re-registration, it may trigger a repeat of this year in 2021, when farmers have already ordered and are applying the chemical, Benbrook says. Benbrook doesn’t see the Court suspending use for 2021. However, it may warn companies this is the last time it will allow this to happen. In 2022, this may leave farmers without the dicamba formulations to apply to their dicamba-tolerant crops, he says. 

Bayer’s Zenteno, though, says that EPA has made some strong statements in the registration that addressed concerns raised by the Court earlier this year. 

“The EPA has spent a tremendous amount of effort to do a science-based review, and has based the new registration on additional data,” she says. 

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