The herbicide Enlist Duo, which contains the choline salt of 2,4-D and glyphosate, was first registered in 2014 for use in genetically engineered (GE) corn and soybean crops in certain states. After granting the registration, the agency discovered that the registrant had made claims of synergy between the ingredients in the herbicide’s formula that had not been shared with EPA at the time of registration. We requested and received a court-ordered remand in January 2016, and then requested and received additional synergy data from the registrant

EPA’s review of those additional data on synergy confirms EPA’s initial findings of no synergy in the Enlist Duo formulation. The finding of the lack of synergy between the ingredients in Enlist Duo resolves the uncertainty that led to the 2016 remand. These data demonstrate that the combination of 2,4-D choline and glyphosate in Enlist Duo does not show any increased toxicity to plants and is therefore not of concern.

At this time, EPA is also seeking public comment on a proposed amendment to the registration to include GE cotton and to extend the use for GE corn, soybean and cotton to an additional 19 states.

Enlist Duo is currently registered for use on GE corn and soybean crops in Arkansas, Illinois, Indiana, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Nebraska, North Dakota, Oklahoma, Ohio, South Dakota and Wisconsin. This proposed decision would allow use on cotton in those states and extend use on GE corn, soybean and cotton crops to include 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.

EPA’s proposal to amend the registration for Enlist Duo to include GE cotton crops and to extend its use on all three crops to 19 additional states is described in the "Proposed Registration Decision of Enlist Duo Herbicide." Public comments on must be submitted by Dec. 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 we expect to issue in early 2017. (Note that the key document for review is the proposed registration decision. The docket also includes the notice of filing of the application for use of 2,4-D on cotton and the petition requesting residue limits to support the new use, which the agency is required to post in the docket under pesticide regulations. Enter comments using the "Memo to Post without an FR Notice" link.)

EPA did a comprehensive review for the 2014 registration and recently again in response to this application to modify the registration to include GE cotton. EPA’s protective and conservative human health and ecological risk assessments re-confirmed our 2014 safety findings. The pesticide still meets the safety standard for the public, agricultural workers and non-target plants and animal species, including species listed as threatened or endangered under the Endangered Species Act. The pesticide is a low-volatility pesticide formulation and includes the following restrictions: No application from aircraft; no application when the wind speed is over 15 mph; buffer zones to protect sensitive areas; and application only with approved nozzles at specified pressures.

Read more about the Enlist Duo Registration here.