Dicamba Extension Granted

The U.S. EPA has extended the registration for dicamba herbicides for over-the-top use in Roundup Ready Xtend crops for two more years.

The agency also handed down more detailed requirements for applicators wishing to use XtendiMax, FeXapan and Engenia herbicides in dicamba-tolerant cotton and soybeans. And, it will require registrants to conduct more studies on volatility and off-target movement during the 2019 growing season.

EPA stated in a press release that the action considered input and collaboration between EPA state regulators, farmers, academic researchers, pesticide manufacturers and other stakeholders.

“EPA understands that dicamba is a valuable pest-control tool for America’s farmers,” acting administrator Andrew Wheeler explains. “By extending the registration for another two years with important new label updates that place additional restrictions on the product, we are providing certainty to all stakeholders for the upcoming growing season.”

Weed scientists such as Purdue University’s Bill Johnson immediately voiced concerns that the changes won’t fully address movement of the herbicide because of volatility. However, he did note that statements on the label do specifically mention keeping proper spray tank pH levels, which relates to volatility.

“It is at least an acknowledgment that volatility can occur, which is a different than the message that has been promoted in the marketplace,” Johnson says.

In the past, states have used section 24(c) of the Federal Insecticide, Fungicide, and Rodenticide Act to pass more restrictive state rules to beef up or refine federal pesticide labels. However, questions remain as to whether states can and will take additional steps.

The new EPA dicamba registration decisions for 2019–2020 include:

> Only certified applicators may apply dicamba over the top of soybeans and cotton. Those working under the supervision of a certified applicator may no longer make applications.

> Prohibits over-the-top soybean applications 45 days after planting or the R1 growth stage, whichever comes first, and prohibits cotton applications later than 60 days after planting or mid-bloom, whichever comes first.

> For cotton, the number of over-the-top applications will be limited to two applications. This is half of what was allowed last year. Soybeans remain limited to two over-the-top applications.

> Applications will now be allowed only from one hour after sunrise to two hours before sunset.

> In counties where endangered species may exist, the downwind buffer will remain at 110 feet, and there will be a new 57-foot buffer around the other sides of the field. The 110-foot downwind buffer applies to all applications, not just in counties where endangered species may exist.

> Every applicator will be required to take dicamba-specific training, and the training will be standardized across the dicamba products.

> Tank cleanout instructions will be enhanced.

> The label will be strengthened to improve applicator awareness on why lower-pH spray solution through tank-mix partners increases the chances for volatility.

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