The following is adapted slightly from a U.S. Environmental Protection Agency (EPA) press release dated July 23, 2025. There are currently no registered dicamba products for over-the-top (OTT) applications to soybeans and/or cotton. In recent years, Illinois had additional state restrictions on the use of these products. Should these products be registered once again, Illinois specific application restrictions must still be followed provided they are once again put in place. For example, EPA proposes a temperature restriction of 95 degrees F, while in recent years Illinois cut off applications at 85 degrees. It is too early to know how this will all play out. While the human health risk assessment findings discussed below are good news, the potential risk to plants is of great concern and must be carefully considered. While dicamba is an important weed management tool for Illinois corn and soybean producers, will these proposed label restrictions be enough to protect nearby, susceptible non-target plants from any potential movement off-target (think gardens and trees)? Will users carefully read and follow all label directions including the new mitigation measures? While this all sounds somewhat complicated, EPA believes that the new labels will be easier to follow with added flexibility for producers.
If you are someone who would be using these products, be sure to provide comments to EPA before August 22, 2025. At this writing, there are fewer than 40 comments on this specific document which is open for comment. However, the docket on dicamba contains 1.24K comments, which you can read through. You can even narrow the focus by searching for specific key words like “Illinois” and “trees”. – Michelle Wiesbrook
EPA’s Proposed registration
The EPA has released for public comment its proposed registration for three end-use dicamba products for broadleaf weed control in dicamba-tolerant cotton and dicamba-tolerant soybean. EPA has conducted a robust human health risk assessment for these proposed products and has not identified any human health or dietary risks of concern. Additionally, the agency is proposing to put several measures in place to protect against the ecological risks found in EPA’s assessment. These new products would give farmers an additional tool to help manage crops and increase yields in order to provide a healthy and affordable food supply for our country.
Dicamba is an herbicide that has historically been used for control of emerged broadleaf weeds in a variety of food and feed crops and in non-agricultural settings. These proposed dicamba products would allow postemergence applications to dicamba-tolerant cotton and soybean, commonly referred to as "over-the-top" (OTT) use. OTT dicamba applications aim to remove emerged broadleaf weed species, particularly those resistant to other herbicides that compete with cotton and soybean plants and potentially reduce crop yield. OTT dicamba products have high benefits in both cotton and soybean for controlling these herbicide-resistant weeds and managing resistance to herbicides in the future.
EPA’s Risk Assessments
In addition to its proposed registration decision, EPA has also released its human health risk assessment, benefits and impacts assessment, ecological risk assessment and draft biological evaluation. EPA has not identified any dietary, aggregate, non-occupational or occupational risks of concern for potential human health exposure from the proposed uses of dicamba on dicamba-tolerant cotton and dicamba-tolerant soybean. Additionally, EPA has not identified any risks of concern for aquatic invertebrates, fish or aquatic plants. EPA concluded low risk for honeybees and other non-listed bees from the proposed uses of dicamba.
As expected of an herbicide, dicamba does pose risk to certain plants. In response to those findings, EPA has developed new, additional proposed mitigations to minimize impact to certain species. With these proposed mitigation measures in place, EPA’s draft biological evaluation predicts that the use of dicamba will not result in a likelihood of future jeopardy for the survival of any listed species, or a likelihood of adverse modification for any designated critical habitat. The proposed registrations also would not pose an unreasonable risk to human health or the environment with these mitigations.
Specifically, EPA is proposing the following mitigation measures on the three products being proposed:
- A single use maximum application rate of 0.5 lb. acid equivalent (a.e.) dicamba per acre.
- No more than two applications allowed with a maximum annual application of 1 lb. a.e. dicamba per acre from all combined dicamba-containing products.
- Prohibition of aerial applications.
- Maintaining a 240-ft downwind buffer.
- The spray solution must include an approved drift reduction agent and pH buffering volatility reduction agent added to the tank in higher percentages as temperatures increase.
- Temperature-dependent application restrictions to manage volatility. Users have flexibility to implement temperature-dependent restrictions by reducing the percent of field treated, including by using precision agriculture techniques, or prohibiting certain tank mixes at higher temperatures. (Note: When the temperature meets or exceeding 85 degrees F, a 40% reduction in area treated must take place or no tank mix partners can be used. However, this option to reduce treated area by 40% would allow growers to return the third day after the initial OTT dicamba application to treat the remaining untreated part of the field. Details are provided in Table 8. in the document, “Memorandum Supporting Proposed Decision to Approve Registration for the Uses of Dicamba on Dicamba-Tolerant Cotton and Dicamba-Tolerant Soybean” located within the docket. Reading the discussion section below Table 8 is highly encouraged as it discusses how the labels will change compared to previous registrations and the reasoning behind it. There is also discussion there on alternative label requirements that EPA is considering.)
- No applications at temperatures above 95 degrees Fahrenheit. (Note: This is for forecasted temperatures. The proposal states, “Maximum temperature must be forecasted by NOAA/National Weather Service not to exceed what’s noted for both the day of application and the day after application.”)
- Three points of mitigation required based on the runoff/erosion mitigation menu.
- Users must access and follow any applicable endangered species bulletin from “Bulletins Live! Two” web-based system. Six points of runoff/erosion mitigation will be required in some pesticide use limitation areas where pesticide exposures are likely to impact the continued existence of a listed species, which may include a reduction in survival or recovery of the species.
- Applicators are required to wear baseline attire (i.e., long-sleeve shirt, long pants and shoes plus socks) along with personal protective equipment including chemical-resistant gloves when handling these products. A NIOSH-approved dust/mist filtering respirator with any R, P, or HE filter is also required for all handlers of the BAPMA-salt-formulated product. There is a restricted entry interval of 24 hours. Use is restricted to a limited number of approved states by certified applicators only. Applicators are required to complete additional dicamba-specific annual training and maintain records of all applications.
EPA understands that the proposed suite of mitigations is not standard and could present operational challenges for farmers. Therefore, EPA is particularly interested in receiving feedback about the temperature-dependent volatility mitigations, percent of field treated restrictions and any science-backed solutions to manage volatility. Detailed information about these mitigation measures is available in the proposed decision in and around Table 8 and in the Proposed Label Requirements section.
Next Steps
After considering public comments on the proposed registration and the draft effects determinations, EPA will decide whether the registration action meets the standard for registration under the Federal Insecticide, Fungicide, and Rodenticide Act. If EPA determines that the registration action can be granted, EPA will finalize the biological evaluation. If a final biological evaluation finds that dicamba may affect any listed species or critical habitats, then EPA will initiate Endangered Species Act consultation and share its findings with the U.S. Fish and Wildlife Service or the National Marine Fisheries Service (collectively referred to as the Services), as appropriate.
During formal consultation, the Services use the information in EPA’s final biological evaluation to inform their biological opinions. They are responsible for making the final jeopardy/adverse modification findings and have the sole authority to do so. If the Services determine in their final biological opinions that additional mitigations are necessary to address any jeopardy or adverse modification determination or to address any incidental take, EPA will work with the registrants to ensure that any necessary registration or labeling changes are made.
To read more about the proposed registration of dicamba and to comment, see docket ID EPA-HQ-OPP-2024-0154 at www.regulations.gov. The public comment period will be open for 30 days, closing on 8/22/2025.
Source: EPA Press release, “EPA announces proposed decision to approve registration for new uses of Dicamba, outlines new measures to protect human health, environment”
ABOUT THE AUTHOR: Michelle Wiesbrook provides subject matter expertise and training in pesticide safety with an emphasis on horticultural weed science. She serves as the Illinois Pesticide Review newsletter editor, collecting and organizing material.