In 2019, while tearing down our bathroom for renovation, we discovered a treasure, a relic of an icon long gone from our U.S. forests. It was paneling from an American chestnut tree and it was beautiful. The panels were several feet wide, much wider than any lumber we can buy today, and the grain was long ad straight, with a honey tone. I was filled with mixed emotions – the excitement of finding something so rare and beautiful yet, sadness that these magnificent trees are no longer part of our forests.

Chestnut paneling. Photo by Marie Woodward

American chestnut (Castanea dentata) trees were once the largest and most abundant trees in the eastern half of the United States, stretching from Maine to Florida. They were estimated to be about four billion in number and considered a keystone species. A lot of wildlife depended on it for survival because it produced a steady supply of highly nutritious nuts every year.  Humans depended on these nuts, too, to feed their livestock and their families, “Chestnuts roasting on an open fire” was once a common practice, not just a line from a Christmas song. The wood from American Chestnut trees was long, straight, and rot resistant, so it was used to build houses and barns, which helped settle America (and created my hidden paneling).

Historical photo of a large American Chestnut from the Great Smokey Mountains of TN and NC.

But in 1904, a fungus, Cryphonectria parasitica, better known as chestnut blight, entered the U.S. from imported Asian chestnut trees. Though the Asian chestnut trees were highly resistant to the blight they carried, the American chestnut had no resistance at all. The result was ecological disaster. Within half a century almost all of the country’s four billion American chestnut trees died, with disastrous consequences for both wildlife and the humans who depended on them.

Chestnut blight from http://www.acf.org

Today, the American chestnut, though not completely extinct, is considered functionally extinct. That’s because while American chestnut trees still emerge from long dead underground chestnut root systems, the blight kills them before they can grow to maturity. However, thanks to science and a nationwide network of volunteers, all is not lost.

Currently there are two programs that are having some success at developing a blight-resistant American Chestnut tree. The American Chestnut Foundation is heading up a breeding program where they are cross-breeding vulnerable early-growth American chestnut trees with blight-resistant Chinese chestnut trees in order to produce an American/Chinese chestnut hybrid with blight resistance. When the hybrid trees mature, through a process called back-breeding, they cross-breed the blight-resistant American Chinese hybrid chestnut with another American Chestnut tree. The goal is to breed out the characteristics of the Chinese chestnut tree, while keeping the blight resistance. This process has been continued for many generations, with the goal of producing a tree that will be 1/16 Chinese chestnut and 15/16 American chestnut. Such a tree, it is hoped, will have all the characteristics of the American chestnut while keeping the blight resistance acquired from the Chinese chestnut. This approach, of course takes much time and effort, but scientists say they are only one generation away from replanting the American chestnuts in natural forests.

Another exciting approach to reviving the American chestnut is underway at SUNY’S College of Environmental Science and Forestry. Scientists there have been working to save the American chestnut through a process called transgenics, which uses a bacteria, called Agrobacterium tumefaciens, to transfer genes from one species of plant to another species.

The SUNY researchers discovered that a gene in wheat detoxifies an acid (called oxalic acid) that is the same acid the chestnut blight fungus uses to attack American chestnut trees. Using transgenics, they have introduced this acid-fighting gene into the American chestnut tree with very hopeful results. The new gene enables the tree to neutralize the blight’s acid without taking on any characteristics of another tree species. The result is a virtually identical American chestnut tree species that can fight off the blight. Scientists hope to cross breed it with young chestnut trees in the wild that have not yet been attacked, and older trees that have survived the blight.

Their plan is to return this mighty species back to America’s forests through three approaches. They will use the new tree to reforest land previously deforested by mining. They will plant trees at historic sites associated with the American chestnut to recover what the landscape looked like historically; and they will encourage the public to plant trees on their own lands. You can join this effort, which has an active group of supporters right here in Connecticut.

To learn more about the Connecticut chapter of the American Chestnut Foundation, visit www.ctacf.org.

By Marie Woodward