American Chestnut Project
Regulatory Status
Current Status
At this time, the transgenic Darling American chestnut with enhanced blight tolerance has been formally deregulated by USDA-APHIS, which concluded that the tree is unlikely to pose a greater plant pest risk than non-modified American chestnuts. This milestone follows a six-year federal review and removes a significant barrier to restoration efforts.
While USDA review is now complete, Darling trees are still undergoing regulatory review by the U.S. Environmental Protection Agency (EPA). This is a continued part of a process by which the safety of transgenic plants are verified before they are publicly distributed or widely planted. The timing of EPA review remains difficult to predict and may involve a multi-phased approval process. Their initial phase will likely impose temporary restrictions that will limit public distribution of Darling seedlings and other plant material, possibly based on geographic regions or existing permitted Darling plantings.
As the first transgenic forest tree being considered for restoration use, the regulatory pathway continues to break new ground. We are actively working with regulators to determine the best path forward for making seedlings available and will share updates as more information becomes available.
For the most recent update about ESF's American Chestnut Research and Restoration Project, please visit Progress Report .
USDA-APHIS Function and Process
USDA-APHIS reviews transgenic plants to determine safety for people and for the environment. We submitted a "Petition for nonregulated Status" to the USDA-APHIS (read the Executive Summary or the full Petition) in January 2020.
USDA-APHIS published two key documents for their review process. These documents, a Plant Pest Risk Assessment (PPRA) and an Environmental Impact Statement (EIS), helped guide its final regulatory decision on the Darling trees. These documents state that Darling American chestnuts with OxO are unlikely to pose a plant pest risk and acknowledge that environmental impacts associated with planting Darling American chestnuts are likely to be either positive or comparable to planting other chestnut varieties.
In August 2026, after thorough review of scientific data, supporting documentation, and public comments, USDA-APHIS officially deregulated the Darling blight-tolerant American chestnut.
EPA Function and Process
The EPA is reviewing our registration submission regarding environmental safety and interactions with the blight fungus. Because the gene that gives Darling trees blight tolerance is associated with a pathogen (the Cryphonectria parasitica fungus), these trees are evaluated under EPA pesticide rules. We are also seeking an exemption from the pesticide registration process, since OxO Darling does not kill the fungus and does not fit into the conventional definition of a pesticide.
FDA Function and Process
The FDA focuses on ensuring food is safe for consumption by humans and animals. Although FDA review is not required to distribute Darling trees, we have submitted nutritional analyses showing that chestnuts with OxO are no different nutritionally than nuts from other American chestnuts. The analyses also confirm the absence of wheat allergens or gluten.
Safety for People and the Environment
A series of articles summarizing various safety tests relevant to the regulatory process were published by The American Chestnut Foundation (read about Nutrition, Wildlife, Plants & Fungi). You can read more about our environmental interaction research on our Environmental Interactions with Transgenic American Chestnuts page.
