EPA Registers New Active Ingredient Pyraclonil

Released on August 24, 2023

The U.S. Environmental Protection Agency (EPA) has registered two pesticide products containing the new active ingredient pyraclonil to control weeds in water-seeded rice in California. EPA’s registration decision includes measures to protect non-target organisms, including federally threatened and endangered (listed) species and their designated critical habitats.

In addition to the registration decision, EPA has finalized the biological evaluation for this pesticide under the Endangered Species Act (ESA). Today’s action furthers the goals outlined in EPA’s April 2022 ESA Workplan (PDF) by identifying potential effects to listed species, implementing necessary mitigation, and initiating the consultation process with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) prior to registration.

Background on Pyraclonil

EPA has approved two products containing pyraclonil: a technical product that can be used to formulate other products and an end-use product that is formulated as a dust-free granule that can be applied aerially to flooded rice paddies. The end-use product is registered for pre- and early post-emergence control of grass, sedge, and broadleaf weeds in water-seeded rice in California only. Notably, it may help control barnyardgrass and watergrass, two problematic weed species for rice growers in the state. Generally, weeds are important to control because they compete with rice plants for valuable nutrients and sunlight, potentially reducing yield if left uncontrolled.

Pyraclonil is also expected to be a useful addition to Integrated Pest Management and Weed Resistance Management programs for water-seeded rice in California due to its efficacy and new mode of action. Rice producers in this area can use pyraclonil in rotation with other herbicides to reduce the potential spread of herbicide resistance.

EPA’s Human Health and Ecological Risk Assessments

Before issuing this registration decision, EPA assessed whether exposures to these products would cause unreasonable adverse effects to human health and the environment, as required by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Based on EPA’s human health risk assessment, there are no human health risk concerns from the registered uses of pyraclonil. However, EPA’s ecological risk assessment identified several risks of concern for the environment, including risks to aquatic plant species, listed and non-listed freshwater fish, listed and non-listed estuarine and marine invertebrates, and listed mammals.

EPA’s Final Biological Evaluation

The Agency also evaluated the effects of the proposed registration on listed species and critical habitats. EPA’s final effects determination found that pyraclonil is likely to adversely affect (LAA) 12 listed species and 10 critical habitats. An LAA determination means that EPA reasonably expects that at least one individual animal or plant, among a

variety of listed species, may be exposed to pyraclonil at a sufficient level to have an adverse effect. This is the case even if a listed species is almost recovered to a point where it may no longer need to be listed. The likely “take,” which includes unintentional harm or death, of even one individual of a listed species, is enough to trigger such a determination. As a result, there are often a high number of LAA determinations. An LAA determination, however, does not necessarily mean that a pesticide is putting a species in jeopardy.

EPA further refined its analysis for the species and critical habitats where it made LAA determinations to predict the likelihood that pyraclonil use could lead to a future jeopardy finding for certain listed species or adverse modification finding for critical habitats. These predictions examine effects of pyraclonil at the species scale (as opposed to one individual of a species). EPA’s draft biological evaluation predicted that, without additional mitigation, the proposed uses of pyraclonil would present a likelihood of jeopardy for two listed species (Sacramento River winter-run Chinook Salmon and Central Valley spring-run Chinook Salmon). EPA predicted no likelihood of adverse modification to critical habitats.

Mitigations 

Based on these findings, the applicant has added the following mitigations to their labeling:

• A water holding period in treated rice paddies after pyraclonil is applied to minimize pyraclonil off-site movement to non-target areas in which listed species live; and
• Practices to 1) prevent water seepage from treated rice paddies through berms and levees, and 2) minimize overspray of pyraclonil granules onto berms and levees.

The applicant has also revised product labeling to include a requirement that users check the Bulletins Live Two! website to identify whether there are any areas where the pesticide cannot be used. Currently, there are no geographically-specific user restrictions, however, the Services may determine these mitigations are necessary during their review.

With these mitigations in place, EPA’s final biological evaluation predicts that the use of pyraclonil will not result in unreasonable adverse effects to non-target organisms or present a likelihood of jeopardy to these species.

Next Steps

Since EPA’s final biological evaluation found that pyraclonil is likely to adversely affect some listed species and critical habitats, EPA has initiated formal consultation and shared its findings with the Services.

During formal consultation, the Services use the information in EPA’s final biological evaluation (i.e., the final effects determination, predictions of the likelihood of jeopardy/adverse modification, and EPA’s mitigations to avoid jeopardy and minimize take) to inform their biological opinions. While EPA has made predictions about the likelihood of jeopardy and adverse modification as part of its biological evaluation, the Services are responsible for making the 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 or adverse modification determination or to address any incidental take, then EPA will work with the registrant to ensure that any necessary registration or labeling changes are made.

The registration decision and final biological evaluation are available in docket EPA-HQ-OPP-2020-0004 at www.regulations.gov.