The American Chestnut: A Resurrection Story?

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UTC's Hill Craddock speaks at last fall's TedX conference, a nationally sanctioned event, near the campus.

UTC’s Hill Craddock speaks at last fall’s TedX conference, a nationally sanctioned event, near the campus.

This story was originally published in the February/March 2015 issue of Chattanooga Magazine.

At the turn of the 20th century stately American chestnut trees dominated the forests along the Appalachian range and its margins from Maine to north Georgia. In some places one in four trees was an American chestnut. In spots they were the only trees to be found.

These giants, sometimes called “the Sequoias of the east,” could be over 100 feet tall, 10 feet or more across at the trunk, and 1,000 years old. One tree in North Carolina was reported to measure 17 feet across at its base!

Chestnuts were a large part of everyday American life and diet during the early years of the last century.

Chestnuts were a large part of everyday American life and diet during the early years of the last century.

American chestnut trees were a major stabilizing presence in the forest ecosystems of the region. They played an important role in holding the soil together, allowing it to develop its subterranean nurturing complexities upon which all plant life depends. They were sources of food, shade, and shelter for bear, deer, wild turkeys, squirrels, and countless other creatures. The chestnuts were a reliable, abundant and critical part of the diet for many game animals. In the early twentieth century one hunter counted “at least” ninety-two chestnuts in a wild turkey he had shot. The bear were robust and lumbering. Squirrel and wild turkey populations were perking along just fine. As a result, families living in the area could depend on a steady supply of meat for their tables. The chestnuts themselves, easy to gather and store, also found their way to the table.

Those tables and other furniture were likely crafted from chestnut hardwood. As Professor William MacDonald of West Virginia University has pointed out, “Chestnut wood played an important role in almost everyone’s life from the time they were rocked in chestnut cradles until they were buried in chestnut coffins. More than one quarter of all the hardwood timber cut in the Appalachians was chestnut.”

Greenhouse 03 (1)That hardwood powered many local economies by providing lumber for buildings, floors, fences, poles, ship masts and railroad ties. The chestnut’s bark and wood were rich in tannins—chemicals used in processing leather. Chestnuts—cast from the trees and found on the forest floor almost four inches deep in some places—were a valuable local commodity worth $4 a bushel in Knoxville. Railroads shipped thousands of pounds of chestnuts to northern destinations.

Everything was going along fine ecologically and economically, but a prelude to disaster reared its head in 1904 in the New York Zoological Park when the supervisor found many dead and dying American chestnut trees in the park. The villain, introduced from Asian species transported to the U.S., was a fungus, a blight that attacked American chestnut trees and eventually girdled them—certain death for any tree.

Chestnut saplings dormant in mid winter await spring, inside seedlings grow.

Chestnut saplings dormant in mid winter await spring, inside seedlings grow.

The pestilence spread with great speed. By 1925 in one North Carolina county, nearly one in five trees was dying from the blight. In 1940 all but a few trees in the entire expansive region were dead or infected. Populations of game animals plummeted. As one local resident of the time observed, “…back when there were chestnuts, bear got so fat they couldn’t run fast; now the poor bear run like the fox.”

The timber was gone, along with the tannin-rich wood and bark. Today, the graceful stately presence of American chestnut trees has faded into the forest’s history, except for shoots put forth by roots still living, but the shoots rarely survive long enough to mature into trees that can reproduce and resupply the food chain.

Volunteers plant a progeny test.

Volunteers plant a progeny test.

However, all may not be lost. Massive efforts to resurrect the American chestnut are underway, here and in other parts of their former range with a long-term goal of returning blight-resistant trees to their former forest homes. The American Chestnut Foundation is breeding these trees. Asian chestnut trees, though much smaller in stature, possess genes that provide resistance to the fungus that causes chestnut blight. The restoration project is set up to breed these genes from the Asian species into the American chestnut while conserving as much as possible of the American species’ majestic and powerful physical presence.

Dr. J. Hill Craddock of the Department of Biological and Environmental Sciences at the University of Tennessee at Chattanooga and local volunteers are active participants in the The American Chestnut Foundation’s program. Dr. Craddock’s specialty is plant breeding, and he is working with other scientists with a broad range of biological specialties to develop chestnut trees that are resistant to the blight. The goal is to breed trees that are essentially American chestnut but contain blight resistant genes from Asian chestnut species.

The use of bucket trucks makes it possible to place and remove pollination bags.

The use of bucket trucks makes it possible to place and remove pollination bags.

“We want to move genes for resistance to blight from the Japanese and Chinese chestnut into the American chestnut population,” says Craddock. The hoped-for result is trees that look and grow like the grand American chestnut of old and produce chestnuts just like their ancestors did, but harbor an inherited resistance to the blight.

If the breeding programs go according to plan, resistant trees will be returned to their former ecological niche in Appalachian forests where they will have a chance to adapt, reproduce and return a dimension of biological diversity that has been absent for decades.

Carrying out the breeding process requires expertise, patience, attention to detail and many volunteers. Volunteers come from all walks of life and share a common interest in the American chestnut and its survival in the wild. Success involves people in many tasks. Pollen must be transported from tree to tree often requiring the use of tall ladders and even bucket trucks. Chestnuts for growing new trees need to be collected, so they can be planted in research orchards. The experimental orchards need mowing and weeding and watering and protection from deer and other varmints every year for the life of the orchard.

Pollination bags 05 (1)Timing is critical. Pollen works its fertilizing ways only when the parts of the female flower that receive pollen and eventually produce nuts are receptive. These chestnuts must be collected at just the right time. They are favorites of squirrels, chipmunks, among many others. Leave them in collection bags too long, and they will disappear. Dr. Craddock emphasizes that his is not a genetic engineering approach.

“We’re not trying to replace the American chestnut. Our hope is that by breeding for blight resistance, we can give the naturally-occurring populations of American chestnut the ability to survive and reproduce, on their own under forest conditions, in a way that will allow natural selection and evolution of the species to resume.”

Saplings are inoculated for blight.

Saplings are inoculated for blight.

If all goes as planned, American chestnut trees, genetically armored against the blight, will once again arise and become welcome inhabitants of the vast Appalachian region.

Dr. Craddock provides the broad picture in a TED talk at: youtube.com/watch?v=bz_NgKnVKxE

Photography courtesy of University of Tennessee at Chattanooga
and by the American Chestnut Foundation

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About Author

Richard (Dick) Morel is a science writer with a keen interest in the Chattanooga community and, where possible, brining the wonder of nature's workings into articles for Chattanooga Magazine.

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