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EPA announces changes to dicamba registration

November 9, 2018
By KRISS NELSON - Farm News news editor ( , Farm News


The U.S. Environmental Protection Agency (EPA) has announced that it is extending the registration of dicamba for two years for "over the top" use cotton and soybean crops.

Over the top use, according to the EPA, is application of the herbicide on to growing plants for use in cotton and soybean plant varieties resistant to dicamba.

According to the EPA, this action was informed by input from and extensive collaboration between EPA, state regulators, farmers, academic researchers, pesticide manufacturers, and other stakeholders.

"EPA understands that dicamba is a valuable pest control tool for America's farmers," said EPA acting administrator Andrew Wheeler. "By extending the registration for another two years with important new label updates that place additional restrictions on the product, we are providing certainty to all stakeholders for the upcoming growing season."

The following label changes were made to ensure that these products can continue to be used effectively while addressing potential concerns to surrounding crops and plants:

Dicamba registration decisions for 2019-2020 growing season

The registration for all dicamba products will automatically expire on Dec. 20, 2020, unless EPA further extends it.

Bob Hartzler, professor of agronomy and an Iowa State University Extension and Outreach weed specialist, said he has several questions regarding the recent EPA's announcement on dicamba but provided some insight regarding the new approach to dicamba management.

In regards to the rule of prohibiting the over the top application of dicamba on soybeans 45 days after planting, he is unsure if this restriction replaces the previous restriction that limited application up to, and including, the R1 soybean stage.

"Regardless, I see very little value of this new restriction," he said. "According to USDA-NASS crop progress reports, the five year average for Iowa soybean planting is 51 percent planted on May 20. Thus, applications would be allowed into July for much of Iowa's soybean acres."

According to Hartzler, in 2017, 90 percent 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," he said.

Information provided by Hartzler stated the label on dicamba includes a growth stage restriction, and has been moved earlier in the season. The initial labels stated that dicamba could be applied up to and including the R1 growth stage, now it states that dicamba must be applied prior to beginning bloom (R1) or no more than 45 days after planting, whichever comes first.

Certification is another new restriction placed on dicamba. Hartzler said persons under the supervision of a certified applicator will no longer be allowed to apply dicamba on Xtend soybeans.

In 2017, the breakdowns of applicators responsible for misuse complaints in Iowa from dicamba on Xtend soybean was 22 percent, 40 percent, and 38 percent for certified commercial, certified private, and uncertified private applicators, respectively.

Hartzler said he doesn't know what percentage of the Xtend beans were sprayed by the various classes of applicators (i.e. did commercial applicators spray 80 percent of the dicamba on Xtend crops).

"These numbers don't suggest the classification of applicator has a big influence on the likelihood of off-target movement," he said. "The new products were changed to restricted use for 2018, so uncertified applicators could not apply dicamba on Xtend soybean in 2018."

The endangered species restriction, Hartzler is assuming will pertain to both plants and animals.

"Iowa doesn't have any plants listed as endangered, there are five species classified as threatened," he said. "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."

This means, that if animals are included in this restriction, most fields in Iowa would require the 57-foot buffer along field edges (the 110 ft downwind buffer is still in play regardless of endangered species). The label refers users to an EPA webpage dealing with endangered species. At this time the bulletins associated with dicamba products have not been posted.

"I am still not aware whether restrictions will deal only with endangered plants or any endangered organism," he said.

The previous labels of dicamba restricted applications, Hartzler added to between sunrise and sunset.

"This has been further restricted to one hour after sunrise and two hours before sunset," he said. "This restriction is intended to prevent applications during inversions. 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."

Unfortunately, Hartzler said he doesn't think these new restrictions will have a significant impact on the problems that have been occurring the past two years.

"I was hoping for something similar to what Minnesota did in 2018, a date and temperature cutoff for dicamba applications on Xtend soybeans," he said. "The Iowa Department of Agriculture and Land Stewardship can develop more restrictive approaches to managing dicamba and I hope they will take this approach."



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