Registration of Enlist Duo and Enlist One
Enlist Duo and Enlist One are herbicides used to control weeds in conventional and genetically-modified corn, cotton, and soybean crops. Enlist Duo, which contains 2,4-D choline salt (2,4-D) and glyphosate dimethylammonium salt (glyphosate), was first registered in 2014. Enlist One, which only contains 2,4-D, was first registered in 2017. These products are registered for over-the-top weed control in 34 states.
In January 2022, EPA renewed time-limited registrations for both products with additional measures to protect plants and animals, including those that are federally threatened or endangered (listed).
- What are Enlist Duo and Enlist One used for?
- Do these products present risks to human health?
- Do these products present risks to the environment?
- What measures are included on the product labels to protect non-target plants and animals from off-field movement of Enlist herbicides?
- How is EPA protecting listed species and their designated critical habitats?
- What measures are included on the Enlist labels to protect pollinators?
- How is EPA addressing the issue of herbicide-resistant weeds?
- How do EPA and the U.S. Department of Agriculture (USDA) work together to regulate Enlist-related products?
- Enlist Duo and Enlist One are approved for use in which states?
- Is the active ingredient in these products, 2,4-D, the same as “Agent Orange?”
Enlist Duo and Enlist One are herbicides used for post emergence control of broadleaf weeds in cotton, soybean, and corn crops, including those that have developed resistance to multiple herbicides.
The active ingredient, 2,4-D, which is in both Enlist One and Enlist Duo, provides control of broadleaf weeds including glyphosate-resistant weeds like Palmer amaranth. The active ingredient, glyphosate, which is only in Enlist Duo, provides control of grass weeds and other broadleaf weeds.
EPA conducted comprehensive human health risk assessments in the past to evaluate the potential risk these pesticides (glyphosate and 2,4-D) pose to humans. The Agency determined that, when used as directed on the label, Enlist Duo and Enlist One pose low risk to human health.
To evaluate the proposed uses of the Enlist products, EPA completed a comprehensive ecological risk assessment that assessed the risks of 2,4-D choline salt (2,4-D), an active ingredient in both Enlist products, and glyphosate dimethylammonium salt (glyphosate), an active ingredient in Enlist Duo. EPA also evaluated the potential effects of these products on federally threatened or endangered (listed) species, and their designated critical habitats, and initiated ESA consultation with the U.S. Fish and Wildlife Service (FWS).
EPA's ecological assessment found direct risks to non-listed and listed plants from pesticide runoff (i.e., pesticide carried off the application site following rainfall or irrigation) and risks to animals that rely on these affected plants for diet or habitat, including non-listed and listed animals and some designated critical habitats. EPA’s ecological assessment also found direct effects to bees and listed species (birds, amphibians, and reptiles) that use corn, cotton and soybean fields for diet and/or habitat.
Based on these findings, EPA implemented a variety of protective measures on the Enlist product labels.
4. What measures are included on the product labels to protect non-target plants and animals from off-field movement of Enlist herbicides?
EPA established many protective measures to reduce off-field movement on the original Enlist product registrations, including:
- The requirement that Enlist herbicides may not be applied from aircraft or when winds are over 15 mph;
- The requirement that users can only use an approved tank mix;
- The requirement that applicators may only use approved nozzles at specified pressures; and
- The requirement that applicators must maintain a 30-foot infield buffer for areas downwind of application.
Additionally, EPA’s 2022 registration action established new protective measures to reduce pesticide runoff, including:
- Prohibiting Enlist product application when rainfall is expected to occur within 48 hours and when soil can no longer absorb water;
- Prohibiting irrigation that would result in runoff within 48 hours of application of the Enlist herbicide products; and
- Requiring users to select from a list of runoff reduction measures to reduce 2,4-D and glyphosate concentrations in runoff, while also providing users with flexibility.
To ensure protection of listed species and their designated critical habitat, Enlist labels contain a variety of control measures to reduce pesticide runoff (see question four). Enlist labels also prohibit the use of Enlist One and Enlist Duo in counties where EPA identified risks to on-field listed species that use corn, cotton or soybean fields for diet and/or habitat. To see which counties are impacted by this measure, see page 16 of the Enlist labels.
With these control measures in place, EPA determined that the use of these products will not lead to jeopardy of listed species or to the destruction or adverse modification of designated critical habitats. EPA also anticipates that the protective measures will reduce the potential for take.
In addition to terms and mitigations to ensure protection of listed species and critical habitat, EPA has required additional mitigation, and education for the protection of pollinators.
Specifically, EPA has implemented a timing restriction for Enlist cotton and Enlist soybean crops to prevent applications of these products while the crops are flowering. EPA has also determined that Corteva must develop, implement, maintain, and annually update a pollinator protection stewardship plan. The purpose of this plan is to address potential impacts from this product’s use to insect pollinators, including bees and butterflies. This plan must include education materials that describe the importance of pollinator protection in agriculture and best management practices to reduce potential pesticide exposure to pollinators including, but not exclusive, to monarch butterflies.
Education materials must also describe label provisions intended to minimize the potential for product exposure to pollinators, including updated environmental hazard and non-target organism advisory statements, and new application timing restrictions. Additionally, the pollinator protection stewardship plan must include conservation activities that result in meaningful restoration of habitat used by monarch butterflies and other insect pollinators to address potential impacts from this product’s use, taking into account species’ range and habitat requirements.
To maintain Enlist herbicides as a useful tool in the face of the increasing development of herbicide resistance in problematic weeds, additional scouting requirements have been added to the herbicide resistance requirements labeling. The scouting requirements are aimed at prolonging the lifetime of 2,4-D choline over-the-top use by targeting applications to field conditions and identifying escapes in an attempt to find resistant populations before they become widespread. The revised label includes the following:
“To aid in the prevention of developing weeds resistant to this product, the following steps must be followed:
- Scout fields before application to ensure herbicides and rates will be appropriate for the weed species and weed sizes present.
- Scout fields after application to detect weed escapes or shifts in weed species.”
Additionally, EPA has made changes to the annual reporting and testing requirements associated with the herbicide resistance management plan, to help facilitate active monitoring of the continued development of herbicide resistance that may change the associated benefits of Enlist One and Enlist Duo. These changes are explained in more detail in Section 10.5 of the Enlist decision document.
8. How do EPA and the U.S. Department of Agriculture (USDA) work together to regulate Enlist-related products?
EPA registers Enlist herbicides and sets safe levels for Enlist herbicide residues that may remain in or on food from those uses. USDA regulates seed that is genetically-modified to be tolerant of Enlist herbicides.
The federal label allows use of Enlist Duo and Enlist One in the following states: Alabama, Arkansas, Arizona, Colorado, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia and Wisconsin.
However, EPA will be prohibiting the use of Enlist Duo and Enlist One in counties where EPA identified risks to on-field listed species that use corn, cotton or soybean fields for diet and/or habitat. To view the counties where Enlist Duo and Enlist One cannot be used, see page 16 of the Enlist labels.
No. “Agent Orange” was a mixture of two different herbicides, 2,4,5-T and 2,4-D, as well as kerosene and diesel fuel. Agent Orange contained high levels of dioxin, a contaminant found in 2,4,5-T that causes cancer and other health concerns in people. EPA canceled all uses of 2,4,5-T in 1985 because of these risks.