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EPA Dicamba Ruling Raises Spirits, Questions, and Concerns

Dicamba makers are happy, but questions linger over federal rules including application dates and times.

Mixed reactions reign following new rules issued by the Environmental Protection Agency (EPA) last night for the use of dicamba formulations in dicamba-tolerant crops in the Roundup Ready Xtend System. 

Companies manufacturing and marketing the products — including Bayer Crop Science and BASF — are pleased. University and Extension weed scientists have questions and concerns. And the Save Our Crops Coalition, a collection of farmers growing tomatoes and other crops, is displeased with the ruling.

“The EPA is in a very difficult position in regulating this technology – whatever they do is going to be criticized by some people,” wrote Bob Hartzler, Iowa State University (ISU) Extension weed specialist in a blog this morning. 

Two More Years

EPA’s decision allows farmers and applicators to apply dicamba in dicamba-tolerant crops like soybeans through the 2019 and 2020 growing seasons. That’s palatable to companies manufacturing and marketing the dicamba formulations — Bayer Crop Science’s Xtend, BASF’s Engenia, and Corteva’s FeXapan. 

“Farmers have told us that Engenia herbicide has given them the cleanest fields they have seen in years,” according to a BASF statement. “Clean fields can lead to higher yields. That means farmers are able to grow more and sell more.”

“XtendiMax is a highly effective, proven broadleaf weed control option that is delivering results for farmers, who have reported 95% weed control satisfaction over the last two seasons,” said Ryan Rubischko, Bayer’s dicamba portfolio lead, in a company news release.

Off-target dicamba inquiries decreased 75% from 2017 to 2018, says Rubischko. “That is in part due to training and education that have been key components directly correlated to that number.” 


The EPA issued restrictions on when applicators can apply the dicamba formulations. In dicamba-tolerant soybeans, applicators may not apply dicamba 45 days after planting and one hour after sunrise to two hours before sunset.

 Hartzler, though, doesn’t think such new restrictions will significantly impact off-target dicamba problems that occurred in 2017 and 2018.

 “I was hoping for something similar to what Minnesota did in 2018, a date and temperature cutoff for dicamba applications on Xtend soybean,” he wrote in a blog this morning.

In 2018, Minnesota prohibited the application of dicamba on dicamba-tolerant soybeans after June 20 and when temperatures reached 85°F.

 “The Iowa Department of Agriculture and Land Stewardship (IDALS) can develop more restrictive approaches to managing dicamba, and I hope they will take this approach,” writes Hartzler.

“The data was clear in 2017 that (off-target) incidents increase after June 20 and especially in July,” says Jeff Gunsolus, University of Minnesota Extension weed specialist.

Kevin Bradley, University of Missouri Extension weed specialist, says if the Missouri Department of Agriculture proceeds with the federal label alone, it likely will mean fewer restrictions for 2019 and 2020 than occurred in some areas of Missouri last year. “For example, farmers, particularly in the bootheel (in southeastern Missouri), would be able to spray it longer into the season than they did last year,” he wrote in an e-mail.

Hartzler sees little value in the new date restriction.

“According to USDA-NASS Crop Progress reports, the five-year average for Iowa soybean planting is 51% planted on May 20,” he writes. “Thus, applications would be allowed into July for much of Iowa’s soybean acres. In 2017, 90% of dicamba misuse complaints to IDALS were associated with applications made after June 15. I believe a date restriction would be more appropriate, a date in mid-June would be my preference.”

Double-cropped soybeans could also receive dicamba applications late into the summer in a state where just federal applications apply.

“There was a large orchard in southern Illinois that noticed its first dicamba symptoms in late July (2018),” wrote Jean Payne, president of the Illinois Fertilizer and Chemical Association in an e-mail. “So, the 45-day restriction does little to address late-summer application in a state like Illinois.”

States may adopt more stringent application restrictions for 2019 and 2020. Ty Whitten, Bayer crop protection lead, says Bayer Crop Science opposes this.

“Unfortunately, Mother Nature doesn’t work on a calendar,” he says. Whitten adds that delayed planting due to wet weather in Minnesota limited dicamba’s effectiveness for controlling weeds due to the June 20 cutoff date. 

Application Hours

The new federal rules tighten the window for applying dicamba. Previously, applications were limited between sunrise and sunset under federal rules. EPA tightened this to one hour after sunrise and 2 hours before sunset.

“This restriction is intended to prevent applications during inversions,” writes Hartzler. “In Iowa, I know spraying in inversions has been a problem, but I don’t believe it is a leading cause of off-target movement and injury. This further restricts time available to apply dicamba, making it increasingly difficult to apply the product legally.”

Certification Status

Hartzler writes that under the new federal rules, persons under the supervision of a certified applicator will no longer be allowed to apply dicamba on Xtend soybeans.

“In 2017, the breakdown of applicators responsible for misuse complaints in Iowa from dicamba on Xtend soybean was 22%, 40%, and 38% for certified commercial, certified private, and uncertified private applicators, respectively,” he writes. “I don’t know what percentage of the Xtend beans were sprayed by the various classes of applicators (i.e., did commercial applicators spray 80% of the dicamba on Xtend crops), but these numbers don’t suggest the classification of applicator has a big influence on the likelihood of off-target movement. The new products were changed to Restricted Use for 2018, so uncertified applicators could not apply dicamba on Xtend soybean in 2018.”

Steve Smith, director of Red Gold (tomatoes) who chairs the SOCC, says this dodges the real point.

“It continues to focus on the applicator (only certified applicators and no just supervisory roles) and more training, instead of the real problem, which is the chemistry itself,” he writes. “Dicamba is dicamba and as of now, it moves where it is not supposed to go.”

Endangered Species 

New federal rules now state that in counties where endangered species may exist, the downwind buffer will remain at 110 feet and there will be a new 57-foot buffer around the other sides of the field. (The 110-foot downwind buffer applies to all applications, not just in counties where endangered species may exist.)

“I assume this restriction will pertain to both plants and animals,” Hartzler writes. “Iowa doesn’t have any plants listed as endangered. There are five species classified as threatened. However, there are several animals listed as endangered, and a quick perusal of the list suggests the majority of Iowa counties have at least one endangered species. Thus, if animals are included in this restriction, most fields in Iowa would require the 57-foot buffer along field edges (the 110-foot downwind buffer is still in play regardless of endangered species).”

What Companies Say

BASF officials say they will continue to help farmers and applicators follow the label and spray on target.

“More than 90,000 applicators were trained in 2018. BASF trained nearly a third of those applicators, and we will continue our training efforts to include the label updates,” according to the BASF press release. “Our website will continue to host a comprehensive set of resources to educate applicators on the most up-to-date information to make on target applications.” 

“For the 2019 season, we’ll continue to work closely with growers and applicators, along with grower associations, state regulators, universities, and others to ensure growers have continued success with XtendiMax with VaporGrip Technology,” says Bayer’s Rubischko.

Bayer officials say the company will continue to take a variety of steps to help ensure customers use XtendiMax successfully in 2019, including: 

  • Evolving and tailoring trainings based on insights gained from the 2018 season. 
  • Enhancing the RRXtend Spray App to offer growers tools and resources to help them plan for successful, on-target applications. 
  • Continuing the technical support call center, 1-844-RRXTEND, to help customers easily access information on best practices and application requirements. 


For Smith and the SOCC, EPA’s ruling is a disappointment.

“We were advocating for a preplant-only label,” writes Smith. “This wouldn’t have totally stopped all the issues, as some trees, orchards, and vineyards would have already been leafed out, but it would have gone a long way toward reducing the problems to a more manageable level.”

The SOCC isn’t alone in that assessment. Several university weed scientists, including those from ISU, recommended preemergence applications only for 2018. 

Long-term, Smith fears this ruling could fuel unprecedented scrutiny about all pesticide applications.

“Having a ‘bad actor’ out there like dicamba is going to do nothing but inflame the public sentiment about crop protectant material to an even greater degree, when the consuming public and rural residents start to realize and understand why trees and landscapes are being injured,” he writes.

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