A revolutionary approach to saving chestnut trees from extinction

Scientists seek federal approval to restore American chestnut trees wiped out 100 years ago

By Mike Lynch

A genetically modified chestnut tree designed to survive a deadly fungus  is moving through the federal approval process as the State University of New York College of Environmental Science and Forestry continues its efforts to restore a tree that once dominated Eastern forests.

The petition, submitted in 2024 by SUNY ESF, for the project is before the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service and is currently subject to a public comment period that ends July 21. The process is to determine if the modified tree will pose “a pest risk,” essentially determining if it will become invasive and have environmental impacts.

So far, it looks good for the application as the USDA determined in its preliminary finding that the “Darling 54 American chestnut is unlikely to pose a greater plant pest risk than its unmodified parent.” 

In addition to the USDA, the project is expected to be reviewed by the Environmental Protection Agency and U.S. Food and Drug Administration. 

If approved, the tree could potentially be used in forest restoration efforts. But even if everything went according to plan, the process of restoring the trees to the landscape would take centuries, according to the Draft Environmental Impact Statement. Chestnut dispersal is slow and the process would require the assistance of people intentionally planting the trees for the first several decades, it states. 

A forest giant lost to disease

American chestnut was once a common tree in the eastern U.S. as far north as the southern Adirondacks, but it fell victim to a fungus native to Asia in the early 1900s. The chestnut blight killed billions of trees. There are still many young trees on the landscape, but they generally only live to be about 20 years.  “They’re not contributing to the ecosystems in the same way that they once did,” said Andrew Newhouse, director of the American Chestnut Research & Restoration Project at SUNY ESF. “So they’re not rare. They’re not even endangered on most lists, but we say they’re functionally extinct because even though there are millions of them, they’re not contributing to the ecosystem.” American chestnuts were once valued for their edible tree nuts and their hardwood for lumber. Plus, they played a key role in nature, as their nuts were especially sought after by wildlife. 

How the modified tree works

This project by SUNY ESF is an attempt to create a version of the American chestnut that is more resistant to the fungus than the original tree. 

The fungus kills American chestnut trees by secreting a toxin once it has entered a tree. As it spreads and kills parts of the tree, it blocks the flow of water and nutrients, and the tree eventually dies. 

“We’ve given the tree a tool to degrade that toxin, so it’s not repelling the fungus, or it’s not preventing the fungus from infecting the tree, but rather it’s allowing the tree to break down this toxin and better survive with blight infections,” Newhouse said.

He said the tree would be the first tree to receive USDA approval for conservation purposes. 

Second try at federal approval, division among advocates

The application before the USDA is a revised version that was originally submitted in 2020 and then resubmitted last year. SUNY ESF had to redo the application because of a labeling error in the first submission. The first application labeled the trees as the Darling 58 when they should have been labeled Darling 54. 

“We provided a revised petition to the USDA to correct the name so the data we’ve collected all along is still accurate,” Newhouse said. 

But the tree and process have caused contention among American chestnut advocates. 

The American Chestnut Foundation had aided this project for about 10 years but withdrew its support in 2023. Interim President and CEO Bruce Levine said the foundation believes the Darling 54’s resistance doesn’t hold up over time and is “not yet suitable to be used for restoration.” 

But the foundation has yet to submit a comment regarding this application, and he said that opinion isn’t pertinent to the current application that is looking at the invasive nature of the plant. 

“That’s APHIS’ call, and that’s that really has nothing to do with our decision to fold support for the program,” he said. 

But the application and tree do have the support of the foundation’s former New York chapter, which split from the foundation earlier this year over the Darling 54. The chapter now has its own nonprofit called the American Chestnut Restoration, which is actively supporting the project. 

“We want people to make comments, but in reality, the USDA has looked at everything, and they don’t see anything wrong with that tree,” said Allen Nichols, president of the new nonprofit. 

What happens if chestnut trees get approved

SUNY ESF has also been partnering with Silvabio, a bioengineering and seedling company that has a license to operate USDA orchards. 

If the tree makes it through the approval process, Newhouse said SUNY would partner with others to distribute the tree.

“Our goal as a research institution is not to be a tree nursery,” he said. “We would be relying on other partners, potentially including state and private and nonprofit partners, to help with scaling up production and distribution of the trees into the future.”