Brooklet, Ga. (October 27, 2020) — At the Cromley Farm, U.S. Environmental Protection Agency (EPA) Administrator Andrew Wheeler announced that EPA is approving new five-year registrations for two dicamba products and extending the registration of an additional dicamba product. All three registrations include new control measures to ensure these products can be used effectively while protecting the environment, including non-target plants, animals, and other crops not tolerant to dicamba.

“With today’s decision, farmers now have the certainty they need to make plans for their 2021 growing season,” said EPA Administrator Andrew Wheeler. “After reviewing substantial amounts of new information, conducting scientific assessments based on the best available science, and carefully considering input from stakeholders we have reached a resolution that is good for our farmers and our environment.”

Through today’s action, EPA approved new registrations for two “over-the-top” (OTT) dicamba products—XtendiMax with VaporGrip Technology and Engenia Herbicide—and extended the registration for an additional OTT dicamba product, Tavium Plus VaporGrip Technology. These registrations are only for use on dicamba-tolerant (DT) cotton and soybeans and will expire in 2025, providing certainty to American agriculture for the upcoming growing season and beyond.

To manage off-site movement of dicamba, EPA’s 2020 registration features important control measures, including:

•  ~ Requiring an approved pH-buffering agent (also called a Volatility Reduction Agent or VRA) be tank mixed with OTT dicamba products prior to all applications to control volatility.
•  ~ Requiring a downwind buffer of 240 feet and 310 feet in areas where listed species are located.

•  ~ Prohibiting OTT application of dicamba on soybeans after June 30 and cotton after July 30.
•  ~ Simplifying the label and use directions so that growers can more easily determine when and how to properly apply dicamba.

The 2020 registration labels also provide new flexibilities for growers and states. For example, there are opportunities for growers to reduce the downwind spray buffer for soybeans through use of certain approved hooded sprayers as an alternative control method. EPA also recognizes and supports the important authority FIFRA section 24 gives the states for issuing locally appropriate regulations for pesticide use. If a state wishes to expand the federal OTT uses of dicamba to better meet special local needs, the agency will work with them to support their goals.  

This action was informed by input from state regulators, grower groups, academic researchers, pesticide manufacturers, and others. EPA reviewed substantial amounts of new information and conducted assessments based on the best available science, including making Effect Determinations under the Endangered Species Act (ESA). With this information and input, EPA has concluded that these registration actions meet Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) registration standards. EPA believes that these new analyses address the concerns expressed in regard to EPA’s 2018 dicamba registrations in the June 2020 U.S. Court of Appeals for the Ninth Circuit. Further, EPA concluded that with the control measures now required on labels, these actions either do not affect or are not likely to adversely affect endangered or threatened species. 

To view the final registration of the dicamba products, visit docket EPA-HQ-OPP-2020-0492 at www.regulations.gov.  

By Dean Malvick, University of Minnesota

Tar spot of corn has continued to spread in Minnesota. This disease was found in Minnesota for the first time in four counties in 2019. In 2020, it has been confirmed in 11 counties in southeastern Minnesota, including one county west of I35 ( https://corn.ipmpipe.org/tarspot-2/).

The last sample of this year with suspected tar spot symptoms was received last week, but it turned out to be the black lesions that are common with mature rust infection (https://corn.ipmpipe.org/tarspot-2/). Most of the counties with tar spot had many different fields confirmed with this disease. Fortunately, all or most of the confirmed tar spot developed only to low levels or late enough such that yield loss was none or minimal.

These results confirm what we suspected, that tar spot would continue to spread in Minnesota. Dry weather in parts of southern Minnesota in July and August likely suppressed tar spot development and spread this year. These confirmed counties only represent where tar spot was found, and do not reflect how much further north or west it may have spread undetected.

Symptoms and Management

Corn tar spot is caused by the fungus Phyllachora maydis. This fungus infects leaves and husks and produces small raised black structures on leaf surfaces. The black structures are firm, smooth, and do not rub off or break open as do rust pustules.  

Tar spot can result in significant corn yield loss, depending on weather, severity, and timing of disease development. Yield loss due to tar spot has not been confirmed in Minnesota. If tar spot develops to high levels before maturity, fungicides can be used to manage it, although optimal timing of applications need to be determined. Proactive scouting can guide potential need and timing for fungicide applications. Risk of this disease is highest where the disease has occurred previously. 

Tar spot appears to respond strongly to weather conditions, in some ways similar to white mold on soybean, and likely is not a major threat when hot and dry weather prevails in late July and August. However, we still have much to learn about tar spot and the risks (high or low?) that it presents to corn production across Minnesota.