U.S. EPA proposes registration of new pesticide (pyraclonil) for use on rice

Date:04-18-2023

The U.S. Environmental Protection Agency (EPA) has released for public comment its proposed registration decision for granular pesticide products containing the new active ingredient pyraclonil to control weeds in water-seeded rice in California. EPA’s proposed registration decision includes measures to protect non-target organisms, including federally endangered and threatened (listed) species and their designated critical habitats. In addition to its proposed registration decision, EPA has also released its draft biological evaluation (BE) for this pesticide under the Endangered Species Act (ESA). Today’s action furthers the goals outlined in EPA’s April 2022 ESA Workplan by identifying potential effects to listed species and proposing protective measures prior to pesticide registration.

Background on Pyraclonil

Pyraclonil is formulated as a dust free granule that would be applied aerially to flooded rice paddies. Currently, it is intended for pre- and early post-emergence control of grass, sedge and broadleaf weeds in water-seeded rice in California only. Notably, pyraclonil would help control barnyard grass and watergrass, two problematic weed species for rice growers in the state.

Additionally, pyraclonil would be a useful addition to Integrated Pest Management and Weed Resistance Management programs for water-seeded rice in California. Rice producers in this area would be able to use pyraclonil in rotation with herbicides that have other modes of action, reducing the potential for herbicide resistance.

Results of EPA’s Risk Assessments and Draft Biological Evaluation

Before issuing this proposed registration decision, EPA assessed whether exposures to these products (one end-use product and one technical product) would cause unreasonable adverse effects to human health and the environment, as required by the Federal Insecticide, Rodenticide, and Fungicide Act (FIFRA). Based on EPA’s human health risk assessment, there are no human health risk concerns from the proposed uses of pyraclonil. However, EPA’s ecological risk assessment identified several risks of concern to 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.

Consistent with the ESA workplan, the Agency also evaluated the effects of the proposed registration (taking into account any mitigations proposed on the draft label by the registrant) on listed species and critical habitats. EPA’s draft BE finds that pyraclonil:

• Will have no effect on 212 listed species and 39 critical habitats;

• May affect but is not likely to adversely affect 6 listed species; and

• 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 species, is enough to trigger such a determination. As a result, there are often a high number of LAA determinations in a BE. 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 for which it made LAA determinations to predict the likelihood that pyraclonil use could lead to a future jeopardy finding for  listed species or adverse modification finding for critical habitats. These predictions examine effects of pyraclonil at the species scale (as opposed to an individual of a species). EPA predicts the originally 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) but no adverse modification to critical habitats. EPA has therefore determined that additional mitigations are necessary to address effects to these listed species.

Proposed Protections

EPA is proposing to require:

• 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.

In accordance with the ESA Workplan, EPA is also proposing a requirement that users must check the Bulletins Live Two! website to identify whether there are any areas where the pesticide cannot be used. Currently there are no area restrictions; however, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) may determine these mitigations are necessary during their review.

With these proposed mitigations in place, EPA predicts that approving the use of pyraclonil would not result in unreasonable adverse effects to non-target organisms or present a likelihood of jeopardy to these species.

Next Steps

After considering public comments on the proposed registration and the draft BE, EPA will determine whether the registration action meets the FIFRA standard and ESA obligations. If EPA determines that the registration action can be granted, EPA will finalize the BE. If a final BE continues to find that pyraclonil is likely to adversely affect listed species and/or their critical habitats, then EPA will initiate formal consultation and share its findings with the Services, as appropriate.

During formal consultation, the Services use the information in EPA’s final BE to inform their biological opinions. While EPA has made predictions about the likelihood of jeopardy and adverse modification as part of its effects determinations, the Services are responsible for making the actual 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 to ensure that any necessary registration or labeling changes are made.

EPA is accepting public comments on this proposal and its supporting documents via docket EPA-HQ-OPP-2020-0004 at www.regulations.gov for the next 30 days.