Washington, DC, USA
September 6, 2023

The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) recently reviewed a walnut tree modified using genetic engineering. The University of California Davis modified the walnut to resist crown gall disease. This disease causes galls that can appear on the roots, trunk, and crown of a tree that can lead to nutrient deficiency and reduced plant growth. We reviewed the modified walnut to determine whether it posed an increased plant pest risk as compared to cultivated walnut.

APHIS found this modified walnut is unlikely to pose an increased plant pest risk compared to other cultivated walnut. As a result, it is not subject to regulation under 7 CFR part 340. From a plant pest risk perspective, this walnut may be safely grown and bred in the United States.

You can view the RSR request from the University of California Davis and APHIS’ response letter on the APHIS website. Our response is based on information from the developers and our:

• familiarity with plant varieties,
• knowledge of the traits, and
• understanding of the modifications.

Under 7 CFR part 340, developers may request an RSR when they believe a modified plant is not subject to regulation. APHIS reviews the modified plant and considers whether it might pose an increased plant pest risk compared to a nonregulated plant. If our review finds a plant is unlikely to pose an increased plant pest risk relative to the comparator plant, APHIS issues a response indicating the plant is not subject to the regulations.

RSR Request – University of California Davis Walnut
RSR Response Letter – University of California Davis Walnut

Website: http://www.aphis.usda.gov/

Published: September 6, 2023