Caution: The use of pesticide chemicals requires approval and pesticide registration by the state of South Dakota. This federal approval refers to the use of the active ingredient dicamba (3,6-dichloro-2-methoxybenzoic acid) in over-the-top applications and does not permit the use of this chemical, any unregistered, or any unlabeled products for over-the-top applications of dicamba in South Dakota. Monitor use approval in South Dakota from the South Dakota Department of Agriculture and Natural Resources and always follow approved label instructions and restrictions.
The Environmental Protection Agency has issued a limited-time registration (two growing seasons: 2026 and 2027) of over-the-top (OTT) use of dicamba on tolerant cotton and soybean. Although this will likely result in this important chemical weed-control tool being reregistered for use in South Dakota soybeans, there are several important caveats to keep in mind.
Not Currently Registered in South Dakota
While the over-the-top application of dicamba has been reviewed and approved by the EPA, there are no products currently registered for that use in South Dakota. A decision will likely be made soon, so be sure to monitor press releases from the Department of Agriculture and Natural Resources. Out of an abundance of caution, be careful about making decisions based on this federal approval, and as always, follow all label instructions.
Changes to Use Restrictions
The EPA review found a need for increased levels of protection to prevent the off-site movement, and off-target effects, of dicamba. These restrictions include:
- Lower rate: maximum of 1.0 lb/acre/year allowed in two 0.5lb/acre applications.
- Volatility reducer: 40 oz/acre of an approved Volatility Reduction Agent required for EACH over-the-top application.
- Runoff mitigation: 3-6 points of runoff/erosion mitigation points acquired through conservation practices required for use (required points dependent on location of application).
Pesticide Use Limitation Areas (PULAs) will apply to applications in South Dakota:
- Temperature dependent applications: applications occurring on a day with forecasted temperatures between 85°F and 95°F on the day of or day after application, a user may only treat up to 50% of their untreated dicamba-tolerant (DT) soybean acres in a county. The remaining DT soybean acres may not be treated until two days after the initial application to reduce risks during conditions when volatility and drift are elevated. No applications may occur if the temperature is forecasted to be at or above 95°F on the day or the day after a planned application, eliminating applications during the highest risk conditions.
- Cut-off date: OTT applications with dicamba cannot be made after June 30 in South Dakota.
Retained Restrictions
The EPA retained several measures to reduce the risk of using dicamba. These conditions were incorporated into their evaluation and must be implemented.
- Restricted-use designation: only licensed applicators may purchase or use dicamba OTT.
- Mandatory annual training: additional training must be completed each year to use dicamba OTT.
- Personal protective equipment: applicators must wear prescribed PPE.
- 24-hour REI: no entry to treated areas allowed for 24 hours.
- Drift reduction agent (DRA): each tank mix for OTT dicamba applications must contain an approved DRA in addition to the volatility reducer.
- 240 ft downwind spray buffer: applicators must implement a 240 ft downwind buffer to protect adjacent areas; label-approved mitigations can reduce this.
- Strict application timing restrictions: OTT dicamba may not be applied during inversions, within 48 hours of forecasted rainfall, if soil is saturated with water, within one hour after sunrise, or within two hours of sunset.
- Proximity restrictions: cannot use if dicamba-sensitive crops or plants are in downwind areas.
- Wind speed requirements: applications can only be made during wind speeds of 3-10 mph.
- Droplet size requirements: applicators must use coarse (341-403 µm) or coarser (404+ µm) spray droplets.
- Low spray height: applications can be no higher than 2 ft above the ground OR crop canopy.
- Tank mix prohibition: tank mixes cannot contain ammonium-sulfate containing products.
- Mandatory record keeping: additional records will be required to be completed by the end of each day of application and kept for inspection.
Temporary Approval
This federal approval for use covers only the 2026 and 2027 growing seasons. Important measures of chemical use data (including weed control success and use compliance) will be reviewed following this time-limited approval to support a long-term ruling.
As this situation progresses, you can count on SDSU Extension to keep you informed. To reiterate caution, there are still several things that need to happen before dicamba OTT can be used legally in South Dakota. A rushed decision may result in negative outcomes, so be cautious with your decision making concerning this announcement.
