U.S. ​EPA proposes to register new uses of pesticide chlormequat chloride

The U.S. Environmental Protection Agency (EPA) has released for public comment its proposed decision to register the first food uses of the pesticide chlormequat chloride to provide farmers with an additional tool to help increase crop yield. Before registering these uses, EPA will need to establish tolerances in or on barley, oat, triticale, and wheat.

Chlormequat chloride is currently registered for use as a plant growth regulator (PGR) in ornamentals grown in greenhouses and nurseries. This pesticide works to control plant size by blocking the hormones that stimulate growth prior to bloom.

In small grains like wheat, barley, oats, and triticale, lodging (the bending over or breakage of small grain stems) is a major production issue. Lodging can severely limit grain yield and harvestability and have detrimental effects on grain quality. As a PGR, chlormequat chloride application decreases the height of the grain plant stem, resulting in reduced lodging and potentially increased grain yield. Compared to other PGRs with similar use patterns, chlormequat allows for more flexibility in application timing, resulting in greater ease of use for small grain producers.

Before issuing this proposed registration decision, EPA assessed whether exposures to this 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 dietary, residential, or aggregate (i.e., combined dietary and residential exposures) risks of concern. EPA’s ecological risk assessment identified no risks of concern to non-target, non-listed aquatic vertebrates that are listed under the Endangered Species Act, aquatic invertebrates, and aquatic and terrestrial plants.

The agency is proposing mitigation measures to address potential risks of concern to occupational workers as well as birds, reptiles, amphibians, mammals, and terrestrial invertebrates:

• Requiring personal protective equipment such as long-sleeve shirt, long pants, socks, shoes and waterproof or chemical-resistant gloves to address occupational risks of concern;

• Requiring 24-hour restricted entry intervals, including posting signs at all reasonably expected points of worker entry to the treated area to address occupational risks of concern; and

• Requiring a mandatory and an advisory spray drift management statement to address ecological risks of concern.

The proposal is now available for public comment in docket EPA-HQ-OPP-2021-0290 at www.regulations.gov for 30 days and will close on May 26, 2023.