UACES Facebook Arizona federal court vacates over-the-top dicamba registration
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Arizona federal court vacates over-the-top dicamba registration

Tuesday’s decision is the latest in an almost decade-long legal back-and-forth over the availability and use of dicamba.

By Drew Viguet
National Agricultural Law Center
U of A System Division of Agriculture

Feb. 7, 2024

Fast facts:

  • U.S. District Court of Arizona vacates dicamba, continuing history of back-and-forth regarding its use
  • Dicamba was previously vacated in 2020 by U.S. Ninth Circuit Court of Appeals

(663 words)

Download related photo of Rollins

FAYETTEVILLE, Ark. — A federal court in Arizona has overturned the 2020 dicamba registrations that allowed over-the-top applications of three dicamba products, XtendiMax, Engenia and Tavium, leaving a cloud of uncertainty for farmers and defendants.

Tuesday’s decision is the latest in an almost decade-long legal back-and-forth over the availability and use of dicamba.

Brigit Rollins, NALC staff attorney
ROLLINS: Arizona court decision leaves uncertainty for farmers, defendants. (U of A System Division of Agriculture file photo)

In an order from the U.S. District Court of Arizona, the court concluded that the U.S. Environmental Protection Agency failed to comply with the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA’s, public notice-and-comment requirements when approving a “new use” of dicamba. The court order is available online.

Dicamba is an herbicide that targets broad-leafed plants and is used to combat weeds that have grown resistant to glyphosate, including palmer amaranth, commonly known as pigweed. Prior to 2016, dicamba has been used as a pre-emergent, meaning that it was applied to the ground in late winter or early spring before crops were planted. Older forms of dicamba were prone to volatility causing the pesticide to move off target and damage nearby fields. By applying dicamba as a pre-emergent, risk of off-target damage was greatly reduced. However, in 2015, Monsanto Co., which is now part of Bayer, released a line of soybean and cotton seeds engineered to be resistant to dicamba. The following year, EPA approved over-the-top use of dicamba for the first time. Several companies brought dicamba products to market.

“The decision to approve over-the-top use of dicamba was very controversial,” Brigit Rollins, staff attorney for the National Agricultural Law Center, said. “Lawsuits challenging that decision were filed almost right away.”

According to Bayer’s website, its dicamba products are registered for use in all but 14 of the 48 contiguous states, including Arkansas.

The Feb. 6 court order from the U.S. District Court of Arizona is not the first time the dicamba registration has been vacated. In June 2020, the U.S. Ninth Circuit Court of Appeals vacated the then-current dicamba registration for violating FIFRA. Following that cancel order, EPA re-registered dicamba for over-the-top use through 2025. Once again, the same parties that had challenged the previous dicamba registration filed a lawsuit against EPA for re-approving over-the-top use.

Wait and see
For now, it’s a wait-and-see situation for farmers who use the products and the defendants.

In an online statement, defendant-intervenor Bayer, said “We respectfully disagree with the ruling against the EPA's registration decision, and we are assessing our next steps. We also await direction from the EPA on important actions it may take in response to the ruling.”

“Now that the court has issued its decision, we’re waiting to see what both EPA and the defendants will do next,” Rollins said. “Last time around, EPA issued its formal cancellation order pretty quickly after the decision, but the agency did allow people who had already purchased dicamba for the 2020 growing season to use up their existing stocks. We’re waiting to see if EPA will do the same on this go around.”

Rollins added that it’s likely the defendants will appeal this ruling.

“If they do, we’ll be waiting to see whether the district court’s ruling is stayed while the appellate court considers the case,” she said.

While the timeline on EPA’s response to the court’s order is uncertain, the decision by the Arizona federal court indicates a forthcoming Notice of Intent to Cancel over-the-top use of dicamba. Currently, Arizona is the only state in the Ninth Circuit where dicamba is available for over-the-top use.

Mention of product names does not imply endorsement by the University of Arkansas System Division of Agriculture.

More on the history of dicamba can be found on the NALC website in a series authored by Rollins, “The Deal with Dicamba.”

Rollins is set to discuss the future of pesticides in the western U.S. at the Western Agricultural and Environmental Law Conference. The event will be held at the University of Nevada, Reno, on June 13-14 with a livestream option available. Conference information and registration is available online.  

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About the National Agricultural Law Center
The National Agricultural Law Center serves as the nation’s leading source of agricultural and food law research and information. The NALC works with producers, state and federal policymakers, Congressional staffers, attorneys, land grant universities, and many others to provide objective, nonpartisan agricultural and food law research and information to the nation’s agricultural community.

The NALC is a unit of the University of Arkansas System Division of Agriculture and works in close partnership with the USDA Agricultural Research Service, National Agricultural Library.

About the Division of Agriculture
The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. The Division of Agriculture conducts research and extension work within the nation’s historic land grant education system through the Agricultural Experiment Station and the Cooperative Extension Service.

The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on five system campuses.

The University of Arkansas System Division of Agriculture is an equal opportunity/equal access/affirmative action institution. If you require a reasonable accommodation to participate or need materials in another format, please contact as soon as possible. Dial 711 for Arkansas Relay.

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Media contact:
Drew Viguet      
Communications & Special Projects Coordinator
National Agricultural Law Center