The American Chestnut Research & Restoration Project at ESF
Progress Report Spring 2026

Dear American chestnut supporters,

We are happy to report that our team remains strong and dynamic, making important strides in academic, regulatory, and scientific realms. We have built new collaborations and strengthened existing ones, notably with the newly renamed American Chestnut Restoration, Inc. (formerly the New York Chapter of The American Chestnut Foundation). We have hosted large meetings that included chestnut field tours, celebrated multiple students completing graduate degrees, published important peer-reviewed scientific articles on Darling 54, and even witnessed the discovery of a rare chestnut bee in our research plots. Updates are described in more detail below. We appreciate your continued interest!

Sincerely,

Andy Newhouse and the ESF Chestnut Team

"When can I get a tree?"

This is the most frequent question we receive, and one we are working hard to answer! However, the response is now largely in the hands of regulatory agencies. We saw progress in 2025 from one agency, USDA’s Animal and Plant Health Inspection Service (APHIS), indicating a likely approval decision in 2026. APHIS specifically acknowledged the name correction (Darling 58 to Darling 54) on our regulatory submissions, and confirmed a lack of environmental risks based on their review. (We thought we might be able to include news of a regulatory decision in this Progress Report – not yet, but hopefully soon!) However, public distribution will also depend on an entirely separate review by the Environmental Protection Agency (EPA), whose process is complex because this is the first wild tree they have reviewed. There is no precedent at EPA for approval of a long-lived wild organism like the American chestnut, so we are working with the agency on creative approaches. Despite these challenges, we are making progress toward initial distribution, which will likely start with expanded research plantings across the American chestnut range. This will be a collective effort, including citizen scientists like many of our supporters, potentially starting within a year.  

Academic Successes

We are proud to announce that five chestnut graduate students finished their degrees in 2025 and 2026. Erik Carlson finished a PhD focusing on DarWin chestnuts (see below) and other novel approaches to restoration using transgenic trees. Master’s degrees were completed by Taylor Wegner (growth of Darling trees and intercropping chestnuts with grapevines), Maya Niesz Kutsch (pollination distance and fire tolerance of chestnut tree bark), Sophia Suriano (soil microbes in chestnut restoration sites and persistence of beech leaf disease nematodes), and Maria Loughran (fire ecology of chestnuts and soil hydrology). Two new graduate students started in 2025, both focusing on methods to test and protect chestnuts as well as other threatened native trees. We will be sharing more about them and their work soon. Apart from graduate degrees, several undergraduate students worked in our labs for research credit, and three research articles on Darling chestnuts were accepted for publication in peer-reviewed scientific journals, with several more articles in progress for likely publication in 2026.

Partnerships and Support

As mentioned above, one of our key partners is now an independent entity and has changed its name from the NY Chapter of TACF to American Chestnut Restoration, Inc. (ACR). ACR held their first meeting under this new name in the fall of 2025 (photo), where they shared exciting updates on their growth and success as an independent entity. They already have members from more than 15 states! ACR’s continued support is much appreciated.

Other partnerships are also thriving, ranging from local schools and nature centers to SilvaBio, a Public Benefit Corporation who will be helping us with tree distribution. We have received new funding from the New York Department of Environmental Conservation (DEC) for research on beech leaf disease (BLD). This has allowed us to successfully apply some of what we’ve learned from chestnut research to another threatened native hardwood tree. We are on track to develop transgenic beech tissues soon, which is good timing as concurrent research is uncovering mechanisms of beech leaf disease.

Thanks to a generous anonymous donor, we were able to purchase a digital droplet PCR machine, a highly sensitive tool that detects miniscule amounts of DNA in a sample. This will enhance the precision of our analyses and allow us to explore research questions that were previously out of reach. Finally, we are incredibly grateful to a private philanthropic foundation for a three-year, $1.5 million grant focused on chestnut restoration and expansion toward other threatened trees. (See press release  for details.)

Tree Production in 2025 

ESF had another productive harvest this year, netting more than 2500 confirmed transgenic seeds despite challenging weather conditions during flower development in the spring. The seedlings that will result from this harvest represent important gains in genetic diversity, to better encompass some of the unique traits and adaptations found across the range of American chestnuts. Successful American chestnut restoration will depend on this diversity and adaptability to provide resilience to other threats beyond blight. In fact, one of the biggest strengths of a biotech approach with oxalate oxidase (OxO) is that it can be crossed into a wide variety of backgrounds while maintaining its function of increasing blight tolerance, in contrast to traditional hybrid breeding, where blight tolerance traits may be lost or diluted in each generation.

We confirmed that homozygous Darling trees (those that inherited the OxO transgene from two transgenic parents) showed good growth and even flowered indoors.  This allowed the first use of homozygous pollen in 2025, which in turn yielded nearly 100% transgenic offspring as expected. One of our scientific articles accepted for publication this year, “Speed Breeding Transgenic American Chestnut Trees Toward Restoration ,” describes these homozygous results along with indoor chestnut pollen production.

Planning for Restoration

Regulatory progress and continued growth of Darling 54 trees mean that we can soon expand research to more realistic American chestnut restoration scenarios in more parts of its historic range. As noted in our 2024 Progress Report, one of our recent publications confirms that Darling 54 trees grow a little slower on average than their non-transgenic relatives, but this difference disappears on some site types (like wooded areas that may be prioritized for chestnut restoration). Related research has also revealed that these growth differences are not consistently or solely due to the energy expended by transgene expression, so there are likely several factors involved. Stay tuned for updates as we continue to investigate.

One of our largest research plantings, called the Demonstration Restoration Forest (depicted above), was conceived by Dr. William Powell in 2019. This plot includes Darling chestnuts along with other trees that grow in similar habitats (oaks, hickories, other hardwood tree species, and white pines). It is located on land previously cleared for a timber sale, making it a realistic restoration model for landowners interested in incorporating American chestnuts into a biodiverse forest. The chestnuts and other tree species in this planting are growing well with excellent survival rates, and the site has been a popular model that collaborators and land managers are likely to replicate pending regulatory approval.

DarWin

The next major iteration of OxO trees after Darling 54 is a line we call DarWin. These trees feature inducible expression of OxO, meaning the generally low level of OxO expression increases in response to wounding and blight infections. (The name combines Darling with Wound inducible, with a nod to Charles Darwin). This change in expression could address the growth rate differences we see in Darling 54 trees and help maximize efficiency within the tree. Only a few DarWin trees were old enough in 2025 to allow growth rate comparisons, but those individuals look very promising (photo). Their growth rates appear similar to non-transgenic control trees, while their blight tolerance is comparable to Darling 54. Many more will soon be ready for growth rate comparisons, and we are planning more detailed experiments in 2026 to assess their blight tolerance and inducible OxO expression. DarWin will require its own regulatory review prior to distribution, but the process should be much quicker after Darling 54 is approved. 

Addressing other threatened species

In addition to the beech tissue culture work mentioned above, we are making important progress with other threatened native trees, including American elm, ash, and Ozark chinquapin. We have transgenic elm trees growing in permitted field plots, which are almost ready for screening for disease and drought stress tolerance. Research is underway on ash trees by a new faculty member in our department, Dr. Jun Lee. This could enhance resistance to Emerald Ash Borer in multiple ash species, and Dr. Lee’s expertise is helping us refine techniques for other trees as well. We are also working to develop early screening methods for multiple species which would let us gather data on disease resistance in tissue culture, before trees are even large enough to grow in a greenhouse.

Finally, we are very close to producing an Ozark chinquapin with the OxO gene from Darling 54! In 2024, we produced the first transgenic Backcross 1 nuts (75% Ozark and 25% American) from our breeding program. In 2025, we planted these seedlings in the field to study their development over time and compare them to full Ozark chinquapin controls, and also grew some of these nuts in a growth chamber for rapid pollen production. In just four months, they produced their first male flowers! By then (July 2025), pollination season was nearing its end, but we were still able to pollinate a few flowers and successfully obtained the first transgenic Backcross 2 nuts (87.5% Ozark and 12.5% American). The seedlings are growing indoors, and we look forward to seeing them produce pollen (hopefully as quickly as their dad). This represents an important step not only toward protecting this understudied “cousin” of American chestnuts, but also toward demonstrating how biotechnological tools can help conserve and protect native trees.