Dicamba Registration Update

November 19, 2018 | Kitt Tovar

The Environmental Protection Agency (EPA) released a notice on October 31st stating that it would be extending the registration of dicamba for over-the top use for an additional two years. This means farmers and applicators are allowed to use dicamba in their operation throughout the 2019 and 2020 growing seasons. The EPA made this announcement after collecting comments from pesticide manufacturers, farmers, state regulators, and other stakeholders.


Dicamba is an herbicide that may be used on dicamba-tolerant corn, wheat, cotton, soybeans, and other crops. It can be used in genetically modified crops that are specifically tolerant to the herbicide. However, during 2017 there were many complaints throughout the country of dicamba injuring non-tolerant plants in agricultural settings. Crop damages may occur when dicamba lands outside the intended area through volatilization or drift. Volatility occurs when the dicamba lands on the surface and then vaporizes into a gas. Drift occurs when the dicamba physically moves through the air to a non-intended area.

Farmers in several different states have brought lawsuits against Monsanto, Dupont, Pioneer, and BASF, the creators of dicamba. These lawsuits are interesting because the plaintiffs have no contractual relationship with the companies. Instead they claim they were victims of dicamba drift because the companies placed an unsafe product on the market. Many of these cases were consolidated this past February into one multidistrict litigation (MDL) in Missouri.

New Changes

Because of the EPA’s extension, farmers will be able to continue to apply dicamba to growing plants in order to control weeds. The EPA released new label updates which place additional restrictions on dicamba including:

  • Only certified applicators may apply dicamba over the top (those working under the supervision of a certified applicator may no longer make applications) 
  • Prohibit over-the-top application of dicamba on soybeans 45 days after planting and cotton 60 days after planting
  • For cotton, limit the number of over-the-top applications from 4 to 2 (soybeans remain at 2 OTT applications)
  • Applications will be allowed only from 1 hour after sunrise to 2 hours before sunset
  • 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)
  • Clarify training period for 2019 and beyond, ensuring consistency across all three products
  • Enhanced tank clean out instructions for the entire system
  • Enhanced label to improve applicator awareness on the impact of low pH’s on the potential volatility of dicamba
  • Label clean up and consistency to improve compliance and enforceability

The Integrated Crop Management News at Iowa State University Extension and Outreach reports that there have been 57 dicamba-related complaints made to the Iowa Department of Agriculture and Land Stewardship (IDALS) in 2018. This compares with 117 in 2017. IDALS has the ability to impose further restrictions than the EPA but so far has chosen not to do so. The registration for over-the-top use of dicamba will automatically expire on December 20, 2020, unless the EPA chooses to extend it.

While farmers and applicators are still allowed to apply dicamba through the 2020 growing season, it is important to remember that improper dicamba application that results in pesticide drift can result in private lawsuits and IDALS enforcement actions.  If you have experienced pesticide drift, you should call IDALS at 515-281-8591 to initiate an investigation.