USDA deregulates genetically engineered Darling 54 American chestnut after six-year review
APHIS found the blight-tolerant tree from SUNY's forestry college poses no greater plant pest risk than an ordinary American chestnut. Opponents had filed the bulk of the comments in the final round, and the college says EPA reviews still stand between the tree and wider planting.
A labeling error made in 2016 meant the tree USDA spent years reviewing was not the one named on the petition. On Aug. 27, after six years and two versions of that petition, the Animal and Plant Health Inspection Service (APHIS) announced its decision: the genetically engineered Darling 54 American chestnut, developed by the State University of New York College of Environmental Science and Forestry (ESF), is no longer a regulated article under USDA’s biotechnology rules[1, 2].
The decision took effect Aug. 28, the day the notice ran in the Federal Register[1]. APHIS concluded that Darling 54 “is unlikely to pose a greater plant pest risk than the nonmodified comparator” and is therefore no longer subject to 7 CFR part 340[1]. Sarah Helming, APHIS’s acting administrator, signed the notice on Aug. 24[1].
The details: what APHIS decided and what it skipped
The tree carries a gene from wheat that produces an enzyme called oxalate oxidase, which APHIS describes as a defense against Cryphonectria parasitica, the fungus behind chestnut blight[3]. ESF filed its petition, numbered 19-309-01p, on Jan. 21, 2020[1].
That petition named a different line, Darling 58. According to APHIS, the two lines were made at the same time with the same transgenes in the same genetic background and express the same proteins[1]. Analyses in 2023 found that essentially all offspring from the first crosses descended from Darling 54 because of the 2016 labeling error, so ESF filed an amended petition in August 2024 correcting the name and adding data gathered since 2020[1]. APHIS then revised its draft risk assessment and draft environmental impact statement (EIS) and reopened comment in June 2025[3].
The EIS never got finished. On July 9, 2025, APHIS announced that it would no longer prepare a National Environmental Policy Act (NEPA) analysis alongside reviews of these petitions[4]. The agency pointed to the Supreme Court’s May 29, 2025, decision in Seven County and wrote that “there is no role for NEPA in the agency’s response to a petition for determination of nonregulated status”[4]. Under the new practice, APHIS first asks whether an engineered organism is a plant pest; if it is unlikely to pose greater plant pest risk than its comparator, the review ends because APHIS lacks jurisdiction, and the agency must issue a determination that the organism is outside part 340[4, 5]. APHIS said it would still publish draft reviews in the Federal Register for comment[4].
On Aug. 18, 2025, APHIS formally withdrew its 2021 notice of intent to prepare the chestnut EIS[5]. The final determination rests on ESF’s revised petition, available scientific data, a plant pest risk assessment and the public comments[1]. APHIS posted the signed determination, the risk assessment and its response to comments in docket APHIS-2020-0030[1, 2].
How did the public comments break?
APHIS’s notice lays out four comment rounds, and the balance shifted as the process went on[1]:
- 2020 petition notice: 4,337 comments received, 4,321 posted; a majority favored deregulation[1].
- 2021 EIS scoping: 3,968 received, 3,964 posted; a large majority opposed[1].
- 2022 draft EIS and risk assessment: 30,455 received, 9,289 posted; a majority favored deregulation. EPA’s three comments said it “did not identify significant environmental concerns to be addressed in the Final EIS”[1].
- 2025 revised petition and drafts: 174,116 received, 4,115 posted; a large majority opposed[1].
The gap between comments received and comments posted comes from how Regulations.gov counts bundled submissions, which can carry many comments under one ID, according to APHIS[1].
In the field: a restoration tree, with nut growers watching
Darling 54 was not built for orchards. ESF describes it as a restoration tree for forests where the American chestnut once dominated, and its researchers say it is not a standalone fix[6]. “They tolerate blight better than any other fully American chestnuts we’ve tested, so they can help restore some of the ecological relationships that were lost to this disease,” said Andrew Newhouse, who directs ESF’s American Chestnut Research and Restoration Project[6].
Newhouse described what the APHIS finding means in plain terms: “This means the trees do not spread in ways that would harm forests, farms, or the environment”[6]. He also called it “the first time a forest tree has been approved,” noting that food crops and some ornamentals had cleared similar reviews[6].
Deregulation does not put trees in nurseries yet. ESF says the trees are not available to the public and that “Additional reviews need to be completed by the Environmental Protection Agency (EPA) before American chestnuts can be distributed to individuals or used for wider restoration projects”[6]. Researchers, the college said, benefit right away[6]. ESF lists SilvaBio Public Benefit Corporation among its partners[6].
Opponents see risk well beyond the research plot. The Canadian Chestnut Council, which breeds non-engineered American chestnuts from surviving Ontario trees, told APHIS in July 2025 that release “will contaminate the remaining population of American Chestnuts”[7]. Its comments argued that the line mix-up “is not simply a naming issue,” saying the inserted gene in Darling 54 caused a 1,069-base-pair deletion in a salinity tolerance gene with unknown effects[7]. The council also cited The American Chestnut Foundation’s December 2023 report of “striking variability in Darling trees’ blight tolerance, significant losses in growth competitiveness,” stunting and higher mortality[7].
The council’s letter touches commercial nut growing directly. It said controlling pollen in “Commercial growers dealing with chestnut orchards” is very different from protecting wild trees, and that hobbyists and nurseries cannot be kept from planting Darling 54 near breeding plots or wild stands[7]. The council has about 35,000 planted American chestnuts in Canada, by its count[7].
Global Justice Ecology Project, a U.S. group, said in July 2025 that more than 170,000 individuals and 440 organizations had opposed the petition[8]. “The ecological risks of this for-profit scheme are far too great and the science is fundamentally flawed,” said Anne Peterman, the group’s executive director[8]. The group asked USDA for a full life-cycle risk assessment of engineered trees and backed an Inspector General investigation of the ESF program and its plans with SilvaBio[8].
Corn and other petitions: the same new rules
The process change matters past chestnuts. The August 2025 notice that dropped the chestnut EIS also dropped one planned in 2021 for a corn line engineered to resist dicamba, glufosinate, quizalofop and 2,4-D, with tissue-specific glyphosate resistance for producing hybrid seed[5]. Under the July 2025 practice, any petition for nonregulated status is decided on plant pest risk alone, without a NEPA document[4]. APHIS has kept the Federal Register comment step for those reviews[4].
On the Hill: no congressional action
The determination is an administrative decision under the Plant Protection Act and APHIS’s part 340 regulations, and it required no vote[1]. None of the sources cited here reports any member of Congress weighing in on the chestnut decision. Fresh Fruit Portal reported the decision on Sept. 1, summarizing APHIS’s plant pest finding[9].
The opposing positions are on the record. ESF and its partners frame the decision as a regulatory milestone for restoration science, with Newhouse adding that it is “good news” for work on beech, elm and ash[6]. The Canadian council and Global Justice Ecology Project had asked APHIS to reject the petition outright, and Global Justice Ecology Project faulted the process on Indigenous consent and conflict-of-interest grounds[7, 8]. APHIS did not adopt their requests, and its notice does not describe a further appeal step[1].
What to watch
- APHIS docket APHIS-2020-0030: the signed determination, final risk assessment and response to comments, including how APHIS answered the gene-deletion and field-performance objections[1, 7].
- EPA review: the next federal step ESF identified before any distribution; no EPA date has been announced[6].
- Opponents’ next move: both opposing groups sought outright rejection; whether either challenges the determination is an open question[7, 8].