Preserving the American Chestnut

Thousands of volunteers around the country work together to ensure the American chestnut stays alive and well.

American chestnuts spiky shell

It’s estimated that chestnut blight killed some 4 billion trees.

Photo By Shutterstock/Matin

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In 2011, Maine forester Glen Rea planted American chestnut seeds in a plot in Unity, Maine, to see if any would survive. Rea, a former chairman of the American Chestnut Foundation, and a handful of volunteers wanted to see if the trees could maintain high blight resistance and endure the harsh winter conditions of the Northeast. 

The trees passed the test. The saplings not only fought off the bitter Maine frost, but they have managed to be highly blight resistant. With the success of his young chestnuts, Rea is now moving forward with a plan to create a seed-breeding orchard in Maine, where he will grow highly blight-resistant chestnuts, and then cull all but one out of every 150 to arrive at the genetic cream of the crop for cross-breeding. 

“We’re really aggressive at this final stage,” Rea says.

It might seem like a difficult job for someone who has an affinity for the American chestnut, but Rea knows it’s necessary.   

“If you can call it ‘falling in love’ with a tree, I did it with the chestnut,” he says. 

Across the Eastern seaboard, volunteers are registering similar success in their attempts to resurrect the American chestnut. In 2012, the American Chestnut Foundation distributed some 72,000 seeds bred at a special Virginia research farm to plant throughout the tree’s historical range as far south as Georgia. The goal is to develop regional seed stock and re-establish a species that once was an iconic part of the American landscape.

The American chestnut annually produces abundant seeds that can feed an ecosystem, it has wonderful rot-resistant timber, and it once created a canopy that earned it the label “Redwood of the East.” The United States was partially built on the timber and seed of the American chestnut, says Mark Double, a West Virginia University research associate in plant pathology.

“You made your cradles with it; you made your coffins with it,” Double says.

In 1905, scientists discovered a new fungus attacking American chestnuts at a New York zoo. At first officials weren’t concerned, but then the chestnut blight spread rapidly. Unified action against the blight was delayed, with some scientists believing it local in origin and something the chestnut could fight off. They were wrong; the fungus came from abroad, and the American chestnut had no natural defense.

“It’s a species that had no resistance whatsoever, and a very sophisticated disease came in,” says Paul Franklin, communications director of the American Chestnut Foundation.

The chestnut fungus proved impossible to contain. Swaths of chestnuts were cut down to create breaks, but the blight jumped the lines, spreading on the feathers of birds and the fur of squirrels or hosting on other tree species. Treating infection was difficult, if not impossible. Soon, officials were raising the white flag.

“The best thing to be done is to chop down the good remaining chestnut trees, worth millions of dollars, use them up and permit nature to grow other kinds of trees in their places,” testified a forest official before a logging meeting in 1926.

It’s estimated the chestnut blight killed some 4 billion trees, and the American chestnut has survived only in isolated pockets, including west of the Rockies, where the blight never reached.

But over time, scientists and tree-lovers working with the American Chestnut Foundation hatched a plan. If the blight came from abroad, then perhaps resistance could be imported, as well. In the early 1980s, forestry officials elected to cross-breed the American chestnut with its Chinese cousin to see if the trees could gain blight-resistance. It’s the trees’ only chance, as American chestnuts can’t self-pollinate; the few that have survived are in danger of dying out for lack of mates.

“We’re basically seeing the end of the species,” says Franklin. “We’re trying to reverse that.”

The breeding was supposed to take 40 years, but it’s gone faster with advances in genetic screening. Foresters first bred the two trees together, and then they deliberately infected the offspring with blight. The process continued, and the hybrids that survived were then bred back to gain more American chestnut genetic stock, while maintaining the Chinese characteristic of blight-resistance. The ACF is now able to grow chestnut seed that is 15/16 American, but still blight-resistant.

Meanwhile, in Wisconsin, scientists and foresters are introducing fungus infected with a virus that retards blight growth. There’s hope this will be an effective treatment for trees already infected with blight, and create a one-two punch to restore the species, says Double.

In West Salem, Wisconsin, lies the largest surviving stand of American chestnuts east of the Rockies. These chestnuts grew from a single line of trees along an old farm fence. After the blight, tree-lovers began to make a pilgrimage to the blight-free stand. Unfortunately, they brought the blight with them, Double believes.

Once the infection was discovered, scientists drilled holes in blight-infected patches in West Salem and injected weakened blight. Trees that were treated longest have responded by best fighting off the blight, and the areas treated for the least amount of time are showing signs of a slowed rate of infection. 

Scientists were surprised a few years ago when they discovered that several treated trees labeled as dead had regenerated their crowns. American chestnuts can keep root systems alive for more than 100 years, but researchers were hasty in their diagnosis, or volunteer researchers may have misidentified the trees as dead. 

“If you are looking up, you can’t tell there’s a dead top. The whole crown looks like it’s full of new foliage,” Double says.

This effort has been largely undertaken by some 6,000 volunteers, since the American Chestnut Foundation has just a handful of staff at its North Carolina headquarters.

The American Chestnut Foundation is particularly looking for volunteers who love trees and are willing to plant what might not make it. American chestnuts infected with blight often live long enough to produce seed, and that can be valuable to the effort. For more information, call 828-281-0047. 

Read more: Reap the benefits of raising nut trees with your family in Nut Trees Provide Wintertime Staples for the Table, and discover the other tree species affected in Spread of Chestnut Blight.