US EPA registers new herbicide active ingredient Glufosinate-P

The U.S. Environmental Protection Agency (EPA) is registering the new active ingredient glufosinate-P that controls weeds in conventional and glufosinate-resistant field corn, sweet corn, soybean, cotton, and canola. In addition to its final registration decision, EPA is also releasing its final biological evaluation for the active ingredient under the Endangered Species Act (ESA). This action is consistent with EPA’s obligations under the ESA and furthers the goals outlined in EPA’s April 2022 ESA Workplan.

The registration also contains mitigation measures to reduce exposure to non-target species and minimize impacts to federally endangered and threatened (listed) species and their designated critical habitats. Glufosinate-P is the first new active ingredient registration where EPA has used its new Herbicide Strategy Framework, released in August 2024, to inform the level of mitigation necessary to reduce exposure to listed species and critical habitat from runoff and erosion. The strategy is part of EPA’s broader plan to efficiently meet its ESA obligations by standardizing mitigation and protecting listed species from herbicides, including conventional herbicides used in agriculture, which allows EPA to meet its ESA obligations for glufosinate-P faster. Based on the Herbicide Strategy mitigation menu, glufosinate-P requires a low level of mitigations to reduce spray drift and other off-field risks.

Results of EPA’s Risk Assessments

Glufosinate-P and glufosinate-P ammonium (an isomer of the currently registered herbicide glufosinate and its ammonium salt, respectively) is a broad-spectrum herbicide that directly inhibits photosynthesis and causes excess ammonia build-up, which is generally toxic to plants in high concentrations.

Glufosinate-P has similar benefits and uses to the currently registered glufosinate herbicide products. These benefits include flexible application timing, which allows for postemergence weed control over the top of glufosinate-tolerant crops and for early season use in non-tolerant canola, corn, cotton, and soybean. The proposed glufosinate-P products result in less chemicals entering the environment compared to the currently registered glufosinate because they only require approximately half the application rate to be as effective.

Background on Glufosinate-P

Before issuing the final registration decision, EPA evaluated the potential hazardous effects and exposures to human health and the environment, as required by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). No human health risks of concern were identified for the uses of glufosinate-P. However, EPA’s ecological draft risk assessment identified potential risks for terrestrial and aquatic plants and chronic risk to mammals, bees, and other terrestrial invertebrates that may forage in treated fields and may be exposed to residues by consuming food exposed to off-site spray drift.

Mitigations

EPA is requiring the implementation of the following mitigation measures to address on- and off-field effects to non-target species, including listed species

• Prohibiting application during rainfall and when soils are saturated or above field capacity;

• Requiring users to visit EPA’s Mitigation Menu Website before application and determine an appropriate strategy for meeting or exceeding the required number of mitigation points as specified on the label;

• Maintaining a downwind buffer between the last spray row and the protection area of 50 feet for aerial application and 10 feet for ground application; and,

• Instructing users to access and follow any applicable endangered species bulletins for the two listed species--the Spring Creek bladderpod plant and the whorled sunflower plant--from ″Bulletins Live! Two″ web-based system for all additional directions and restrictions.

With these mitigations in place, EPA’s final biological evaluation predicts that the use of glufosinate-P will not result in a likelihood of future jeopardy of any listed species, or a likelihood of adverse modification for any designated critical habitat.

EPA has initiated ESA consultation and shared its findings with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (collectively referred to as the Services). During formal consultation, the Services use the information in EPA’s final biological evaluation to inform their biological opinions. While EPA has made predictions about the potential likelihood of future jeopardy/adverse modification as part of its biological evaluation, the Services are responsible for making the actual final jeopardy/adverse modification findings and have the sole authority to do so. If the Services determine in their final biological opinions that additional mitigations are necessary to address any jeopardy/adverse modification determination or to address any unintentional harm known as incidental take, then EPA will work with the registrant to ensure that any necessary registration or labeling changes are made.

All the supporting documents related to glufosinate-P are available in EPA-HQ-OPP-2020-0250. Please note that draft labels for BASF products are available in EPA-HQ-OPP-2020-0250 and the draft labels for MCCLS products are available in EPA-HQ-OPP-2020-0533.