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EPA Extends Dicamba Products Registered for “Over-the-Top” Use
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By Lisa M. Campbell, James V. Aidala, and Timothy D. Backstrom

On October 31, 2018, the U.S. Environmental Protection Agency (EPA) announced that it is extending the registration of dicamba for two years for “over-the-top” use (application to growing plants) to control weeds in fields for cotton and soybean plants genetically engineered to resist dicamba.  EPA states that the registration for these dicamba products will expire on December 20, 2020, unless EPA decides to further extend it.  EPA states that the label changes described below were made to ensure that these products can continue to be used effectively while addressing potential concerns to surrounding crops and plants.  EPA’s dicamba registration decisions for the 2019-2020 growing season are:

  • Two-year registration (until December 20, 2020);
  • Only certified applicators may apply dicamba over-the-top (those working under the supervision of a certified applicator may no longer make applications);
  • Prohibit over-the-top application of dicamba on soybeans 45 days after planting and cotton 60 days after planting;
  • For cotton, limit the number of over-the-top applications from four to two (soybeans remain at two over-the-top applications);
  • Applications will be allowed only from one hour after sunrise to two hours before sunset;
  • The downwind buffer for all applications will remain at 110 feet, but in those counties where endangered species may exist, there will also be a new 57-foot buffer around the other sides of the field;
  • Clarify training period for 2019 and beyond, ensuring consistency across all three products;
  • Enhanced tank clean out instructions for the entire system;
  • Enhanced label to improve applicator awareness on the impact of low pH’s on the potential volatility of dicamba; and
  • Label clean up and consistency to improve compliance and enforceability.

EPA states that it has reviewed substantial amounts of new information and has determined that the continued registration of these dicamba products with the specified use restrictions meets the Federal Insecticide, Fungicide, and Rodenticide Act’s (FIFRA) registration standards.  EPA also determined that extending these registrations with the new safety measures will not affect endangered species.  More information on this extension is available on EPA’s website; more information on other dicamba issues is available on our blog.

Commentary

As expected, this decision allows the continued use of the newer dicamba formulations intended to be applied on dicamba-resistant crop varieties.  Of particular note is that EPA has not granted a permanent Section 3 registration, instead granting a time-limited, two-year registration which EPA states will expire at the end of 2020.  This will allow EPA more time to assess in more detail whether the new use restrictions will further reduce problems of misuse, label complexity, or unexpected drift which have been reported in past growing seasons. 

The most vexing issue behind plant injury reports over the past few years is whether these reports are mostly due to misuse (e.g., applicators who do not use the new formulations designed to reduce volatility, which is a label violation since the “old dicamba” product is considered more prone to cause drift injury), or, are due to characteristics of the new formulations which are not yet fully understood and which lead to unexpected volatility and other drift problems.  Some have also argued that problems are also due to the difficulty (or reluctance) in following the more prescriptive requirements for the new formulations.  The two-year renewal will continue to see EPA closely monitor injury and misuse reports, as well as continued academic and registrant research into the likely cause of any reported problems.

EPA’s decision also imposes further requirements for additional training, timing, record-keeping, and stewardship when using the new dicamba formulations that are designed to reduce or to eliminate those plant injury reports that are not clearly attributable to misuse of the older dicamba products.  EPA will rely on state officials to report and evaluate the experience of users in their respective states, especially concerning whether the additional training and stewardship requirements significantly reduce local injury reports.