Glyphosate resistant pigweed will be a target for Enlist Duo which EPA has just approved for an expanded label

Glyphosate resistant pigweed will be a target for Enlist Duo, which EPA has just approved for an expanded label.

EPA to expand use of herbicide Enlist DUO

EPA expands Enlist Duo label More states added Environmental groups express outrage

While environmentalists are in an uproar over an Environmental Protection Agency (EPA) proposal that would more than double the number of states allowed to use a new version of the popular weed killer Enlist Duo, agricultural producers across much of the nation are applauding the proposal as a way to prevent yield and profit loss from growing glyphosate resistant weed varieties.

Last week EPA officials proposed increasing the number of states authorized to use the weed killer from the existing 15 states to a total of 34 states, action that appears to be contrary to a move last year to vacate the product's registration because it potentially posed a risk of being more toxic to non-targeted plants than first thought.

But EPA said that action last November was in direct response to information provided by manufacturer Dow AgroSciences who was the first to indicate the potential for risk to other plants as a result of its use.

Enlist Duo was developed using a combination of glyphosate and an updated version of an older herbicide, 2,4-D, in response to a growing problem of herbicide resistance in some genetically engineered crops. Enlist was designed specifically for use in new strains of genetically modified corn and soybeans.

After Dow AgroSciences issued those concerns to the agency last year, EPA submitted a court filing with the 9th U.S. Circuit Court of Appeals indicating the agency was reconsidering its position on registration as a result of new information from Dow.


After that court action last year, environmental groups expressed their support of EPA action.

"With this action, EPA confirmed the toxic nature of this lethal cocktail of chemicals, and has stepped back from the brink," said Earthjustice Managing Attorney Paul Achitoff last November. "Glyphosate is a probable carcinogen and is wiping out the monarch butterfly, and 2,4-D also causes serious human health effects, and the combination also threatens endangered wildlife."


Following court action last year, Dow AgroSciences issued a statement calling for a rapid resolution to the issue because of pressing needs of U.S. farmers for access to Enlist Duo to counter the rapidly increasing spread of resistant weeds. Company official voiced optimism that new evaluations would result in a prompt resolution of "all outstanding issues."

The 2,4-D ingredient used in Enlist is nothing new to farmers, and is currently used on a number of crops including wheat, pastures and on home lawns. It is one of the world's most popular herbicides and the third most popular in the United States. Groups opposed to expanded use of 2,4-D say they are concerned about its toxic effects and the potential for drift that could pose dangers to other plants and people.


While environmentalists were quick to applaud the EPA move last year, they strongly oppose EPA's latest proposal issued last month to expand its use to more states.

George Kimbrell, senior attorney with the Center for Food Safety, accused the EPA of "capitulation to the agrichemical industry." The Washington-based advocacy group was among the environmental and food safety groups that sued to rescind approval of Enlist last year. Kimbrell and others opposed to expanded use say they are outraged that the EPA would "suddenly have a change of heart."

EPA officials, however, say their decision to expand use of the product is based upon a comprehensive review of Enlist since last year and say they have determined that the product "does not show any increased toxicity to plants and is therefore not of [further] concern."

According to an EPA online statement, Enlist Duo was first registered in 2014 for use in GE corn and soybean crops in six states, and later in nine more states.

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"After completing a rigorous analysis of all the scientific studies, EPA is proposing to amend the registration of Enlist Duo to include use on GE cotton in the existing 15 states. The Agency is also proposing to extend the use of Enlist Duo for GE cotton, corn and soybean crops to an additional 19 states."

EPA says when used according to label directions, Enlist Duo is safe for everyone, including infants, the developing fetus, the elderly and more highly exposed groups such as agricultural workers.

"Use of Enlist Duo is safe for the environment, including endangered species. EPA assessed risks from the 2,4-D choline salt to endangered species and found no effect on listed species from this active ingredient in the approved use areas when the product is used according to label directions."


Weeds are becoming increasingly resistant to glyphosate-based herbicides and are posing a serious problem for farmers. Dow officials say Enlist Duo provides an additional tool to reduce the spread of glyphosate resistant weeds and they are “requiring certain measures to ensure that use of Enlist Duo successfully manages weed resistance problems.” 

Dow Chemical Company said in a statement this week that it is "pleased" with the proposal.

While the weed killer is currently approved for use on soybeans and corn, the EPA proposal would allow its use in cotton as well.

The EPA had previously approved Enlist Duo for use in Arkansas, Illinois, Indiana, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Nebraska, North Dakota, Oklahoma, Ohio, South Dakota, and Wisconsin.

But under terms of the latest proposal, the product could also be used Alabama, Arizona, Colorado, Delaware, Florida, Georgia, Kentucky, Maryland, Michigan, North Carolina, New Jersey, New Mexico, New York, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and West Virginia.

Public comments to EPA must be submitted by December 1, 2016, to EPA docket #EPA‑HQ‑OPP‑2016‑0594 at After the comment period closes, EPA will review all of the comments and reach a final decision, which is expected in early 2017.

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