Check Dicamba Spray Restrictions
Producers in Illinois, Indiana, Iowa and South Dakota who intend to apply over-the-top (OTT) dicamba herbicides this growing season will have a shorter application window in which to do it. This spring, EPA approved some labeling amendments that further restrict the use of XtendiMax, Engenia and Tavium herbicides.
For 2023, the revised federal labels for OTT dicamba herbicides contain the following prohibitions:
-- no application on dicamba-tolerant (DT) soybeans in Iowa, Illinois and Indiana after June 12 or V4 growth stage, whichever comes first
-- no application on DT cotton in Illinois, Indiana and Iowa after June 12 or first square, whichever comes first
-- no application on DT crops after June 20 in South Dakota.
In Minnesota, the same use restrictions remain from 2022:
-- no application on DT crops after June 12 south of Interstate 94
-- no application on DT crops after June 30 north of Interstate 94
-- no application when the forecast high temperature exceeds 85°F.
Illinois also maintains an existing state restriction that prohibits OTT dicamba application if the air temperature exceeds 85°F. In states without label amendments, the cutoff dates are June 30 on DT soybeans and July 30 on DT cotton.
BASIS FOR AMENDMENTS
In letters posted on the docket announcing the dicamba label amendments, Lindsay Roe, chief of the Herbicide Branch within the EPA Office of Pesticide Programs, Registration Division, wrote that the registrants of three dicamba products registered for over-the-top use -- namely BASF, Bayer and Syngenta -- proposed a June 12 cutoff date for Illinois, Indiana and Iowa following discussions with those states. The registrants also proposed a June 20 cutoff date for South Dakota as recommended by that state.
The letters further state that registrant-provided rationale for the June 12 cutoff date was based on a reduction in off-target movement as a result of decreased temperatures, reduced plant height earlier in the season, the opportunity for applications to be spread more evenly through the season and indications of improvement in Minnesota during the 2022 season using that date.
"Restricting the application to a time when temperature is reduced both on the day of application and in the days following application is likely to reduce the potential for volatilization of dicamba," Roe wrote. "EPA views these dates as directionally correct to reduce temperatures at which applications are performed."
In 2017 and 2018, EPA amended the registrations of all OTT dicamba products following reports that growers had experienced crop damage and economic losses resulting from off-site movement. In June 2020, the 9th U.S. Circuit Court of Appeals vacated the 2018 registrations on the basis that "EPA substantially understated risks that it acknowledged and failed entirely to acknowledge other risks."
In October 2020, EPA issued new registrations for two dicamba products and extended the registration of a third. All three included new measures intended to prevent off-target movement and damage to nontarget crops and other plants. Despite these measures, dicamba-related incidents have continued. EPA is reviewing whether OTT dicamba products pose unreasonable risks to nontarget crops and other plants, or to federally listed species and their designated critical habitats.
Unless EPA takes further action, the registrations for these OTT products will automatically expire in December 2025. Currently, all uses of dicamba, including preemergent and OTT applications, are being assessed in registration review, which the agency conducts at least every 15 years.
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