The American Chestnut Research
Progress Report 2024

The American Chestnut Research and Restoration Project at SUNY ESF continues to make important progress as we work to bring the American chestnut tree back. Analysis of data collected from test plots of Darling American chestnut trees is ongoing, providing the ESF team with valuable new information. At this stage we believe that Darling is suitable for release and further study as part of the restoration effort. It fulfills its primary goal of being an American chestnut with enhanced tolerance to chestnut blight, while not exhibiting any safety or major performance risks.

As many of you know, The American Chestnut Foundation (TACF) made a unilateral decision late last year to cease working with us on Darling. We do not agree with this decision and feel it would be in the best interest of American chestnut restoration for all interested parties to work together to find solutions. ESF continues to work closely with a number of organizations including the New York Chapter of TACF, research institutions, conservation groups, nature centers, and others committed to restoration of the American chestnut tree.

In late 2023, ESF discovered a labeling error between two Darling varieties (54 and 58) that were developed at the same time. The labeling is being corrected and new procedures are in place to ensure it does not happen again. We immediately contacted regulators about the situation and are following their guidance for submitting updates. We have acknowledged this clerical error and have accepted responsibility. It is important to recognize that it does not impact our results to date, the pursuit of regulatory approval, safety of the trees, our continued research or ESF’s commitment to restoring the American chestnut.

ESF is keeping USDA, FDA and EPA regulators informed about our research as we move through the stringent review process. Regulatory approvals focus on a variety of factors, most importantly investigating whether the tree poses a health or safety risk to humans and the environment. We support and are actively cooperating with this vital process. Approval of Darling trees would allow for other trees containing the important OxO gene sequence, like the recently developed DarWin, to be investigated more efficiently in the future. Successful restoration of the American Chestnut will require multiple tools and multiple tree varieties, and our work is focused on this solution.

Overall, Darling trees are shorter than their non-transgenic relatives, but height varies based on several factors including family background, environmental factors, and size at initial planting. We are in the process of selecting the tallest Darling trees for future breeding, using scientific approaches to address scientific concerns. However, slower growth does not indicate the trees are unsuitable. A tree that grows slower, showing improved blight tolerance, is a major milestone toward American chestnut restoration.

We consider the Darling’s chestnut blight tolerance to be a critical discovery towards restoration of the American chestnut. As with all chestnuts, including Asian varieties considered resistant to blight, Darling trees can and do get blight. The key for restoration is that trees can survive and reproduce in their natural environment. On average, Darling trees have better blight tolerance than any other American chestnut currently available, and this trait can be
consistently inherited by multiple generations of offspring. Additional study is necessary to assess further potential of the Darling American chestnut compared to similar varieties, but approval of Darling trees with enhanced blight tolerance would be a critically important step.

ESF has been contacted by a number of groups, including members of state chapters of The American Chestnut Foundation, with support, enthusiasm for the progress that has been made and appreciation for our transparency. As part of our commitment to keep interested parties informed of our progress, ESF plans to take part this year in the New York and other state chapter meetings of The American Chestnut Foundation. In July, we will help host a combined meeting of the Northern Nut Growers Association and Chestnut Growers of America that will take place in Syracuse. ESF will also host a chestnut research working group called NE-2333, a gathering of leading academic researchers in September. Exchanging ideas and discussing what we have learned with others will help achieve the restoration goal we all share.

ESF has been clear from the start that we believe there will never be a single solution for American chestnut restoration. Darling and its offspring were never intended to be ultimate selections or replacements for American chestnuts, but they do represent an important step in the process. The long-term goal is to breed blight-tolerant OxO trees with diverse existing American chestnuts, including remnant wild trees as well as trees from breeding programs, to rescue genetic variation that exists within this species. Starting this process with Darling will help improve current lines, inform development of future lines, and preserve existing genetic diversity of the species. There are, and will be, other threats to this iconic tree, so many different tools must be incorporated in the broader restoration efforts.

ESF is committed to rigorous science and discovery. One focus area of research is on preservation and restoration of our critical tree ecosystem that includes the chestnut and other trees native to North America that are threatened by disease and environmental factors. ESF is demonstrating this priority by hiring five new faculty positions centered around a Tree and Ecosystem Restoration Program, which will build on the chestnut project and expand to other species. Our broad focus around preserving, enhancing and restoring tree ecosystems is crucial because these plants are vital to so many things that support diversity, climate and life on Earth.

The American Chestnut Research and Restoration Project is just one of 30 research institutes and centers that ESF either currently manages or collaborates to run. Significant advances are being made by many ESF research programs, as exemplified by the progress with the Darling American chestnut. We are committed to continuing this important work and expanding our efforts in positive and productive ways.

ESF is committed to keeping the American chestnut community informed about our progress. You can keep up with some of the latest news by visiting The American Chestnut Research and Restoration Project update page on our website. ESF also updates the ESF Darling Chestnut Science Summary page as new data becomes available. URLs for both are provided below.

• The American Chestnut Research and Restoration Project Updates
• ESF Darling Chestnut Science Summary