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Ohio State University Extension


Dicamba registration vacated

On February 6th, 2024 the 2020 registrations for the three dicamba products labeled for over-the-top applications in soybean (Xtendimax, Bayer; Engenia, BASF; and Tavium, Syngenta) were vacated by a federal court in Arizona. The court found the EPA in violation of the Federal Insecticide, Fungicide, Rodenticide Act (FIFRA), the Endangered Species Act (ESA), and the Administrative Procedures Act (APA). The primary concern was a failure to adhere to the notice and comment mandate required by FIFRA for new use pesticide registrations. Read more about the court’s analysis in the Ohio Ag Law Blog.

There has been much speculation about the next steps and the likelihood of an EPA appeal. It is uncertain whether or not any challenges to the court’s decision will be successful, and if EPA will issue an order allowing existing stocks of seed and chemical to be legal for use in 2024 for those who have already made purchases. At present, dicamba is not an option for over-the-top applications in soybean in the U.S. It is likely that more information will be released in the coming weeks, and we will continue to put out information as it becomes available.

Since the last challenge to the dicamba registration in 2020, many Ohio growers that utilize herbicide-resistant soybean systems have transitioned to the Enlist technology. For those that utilize the XtendFlex soybean technology (dicamba, glyphosate, and glufosinate resistant), there is still the ability to use glufosinate for postemergence weed management. PPO inhibitors (fomesafen, lactofen, etc.) remain a POST option in any soybean system. Timely applications based on weed size and adequate environmental conditions are increasingly important in situations where glufosinate and PPO inhibitors are relied upon as POST options. Where Xtend soybeans (resistant to dicamba and glyphosate) are used in fields with populations of waterhemp and other glyphosate resistant or otherwise difficult to control weeds, the use of effective soil-applied preemergence residual products will be especially critical. Preemergence residuals reduce the population density of these weeds present at the time of the POST application, which can improve control.

To read the full court decision in Center for Biological Diversity v. EPA, visit this link. For questions related to this topic or other weed management concerns, reach out to Alyssa Essman at or (614) 247-5810.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.