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EPA Proposes Registration of Two Herbicides Containing New Active Ingredient

For Release: September 9, 2020

The U.S. Environmental Protection Agency (EPA) is accepting comments on the proposed registration of two products containing Pseudomonas fluorescens strain ACK55 (P. fluorescens ACK55), a new microbial active ingredient to be used as a pre-emergent herbicide.

Specifically, EPA is proposing to register a manufacturing-use product and an end-use product containing P. fluorescens ACK55 that will suppress the growth of invasive grasses.

Since P. fluorescens ACK55 is a naturally occuring bacterium that must become established in the soil to provide optimal pre-emergent herbicidal effects, suppression of certain invasive grasses may take two to five years.

P. fluorescens ACK55 products are expected to control grasses associated with wildfires that can lead to increased air pollution, loss of property, and loss of habitat for native wildlife.

In concurrence with the proposed registration actions, EPA will be establishing a tolerance exemption for residues of P. fluorescens ACK55 in or on all food when it is used in accordance with label directions and good agricultural practices.

P. fluorescens ACK55 is not expected to be toxic, pathogenic, irritating or infective to humans. Adverse effects to non-target organisms, including honeybees, are also not expected.

The public comment period will be open for 15 days in docket EPA-HQ-OPP-2017-0336 at, starting Sept. 9, 2020.