American Chestnut Restoration
A Closeup of The American Chestnut Cooperators Foundation
An example of the size and majesty of the pre-blight American Chestnut
American Chestnut in History
Prior to the introduction of the Chestnut Blight around 1900, the American Chestnut, Castanea dentata, was easily the most valuable tree in the eastern forests and was the dominant tree species. American Chestnuts made up about 25% of the forest tree population and often existed in pure stands. The nuts, bark, and lumber were an important part of the Appalachian economy. The late blooming, drought resistant native Chestnut provided a reliable source of mast for wildlife. American Chestnut bark was rich in tannin and was the source of choice for extracting it. The lumber was durable, straight-grained, and comparable to Redwood in its rot resistant qualities. The American Chestnut was also quick to regenerate from stumps making it the premier lumber tree of the Eastern United States. American Chestnut wood was used in everything from utility poles and split rail fences to high quality furniture. The lumber from buildings and long dead trees is still highly sought and commands a premium price.
Surviving American Chestnut in Natural Range
Around 1900, the blight arrived in the New England area on Asian Chestnuts and quickly began decimating the native Chestnut population. By the early 1940's, virtually all of the 4 billion American Chestnuts in their natural range were dead or dying. Since that time, the species holds on, surviving as stump sprouts and small understory trees. The blight kills the trees to the ground leaving the roots unaffected. Shoots grow from the roots and may live for some years before the blight kills them again.
American Chestnut Natural Range
Chestnut Breeding to Develop a Timber Chestnut
After it was apparent that the American Chestnut would be completely decimated, the USDA and others began efforts to breed a blight resistant Chestnut to replace it. Most of these efforts focused on the use of Asian Chestnuts with resistance and Asian-American hybrids. These efforts have been largely unsuccessful in developing a timber-type Chestnut that will survive and compete in Appalachian forests. Today, with a better understanding of genetics, breeding, and propagation methods, the development of mostly American forest-type hybrid Chestnuts is progressing notably with trees to be released to the public within a few years.
American Chestnut Restoration:
Great progress in restoring the American Chestnut is being made by the American Chestnut Cooperators Foundation. Their breeding program has been able to increase American Chestnut native resistance by selective breeding of "Survivor Trees". With increased resistance, biological controls, and major breakthroughs, the pure American Chestnut may soon be back in our forests.
American Chestnut Cooperators Foundation
The American Chestnut Cooperators' Foundation (ACCF) is a nonprofit scientific and educational foundation dedicated to restoring the American Chestnut to its former place in our Eastern hardwood forests. Priorities include the development of blight-resistant all-American chestnuts and economical biological control measures against chestnut blight in the forest environment.
"All-American intercrosses" defines the breeding strategy of the ACCF, at Virginia Tech and Concord College, WV. Elkins & Griffin think there may be several different characteristics that favor blight resistance. By making intercrosses among resistant American chestnuts from many locations, they expect to improve upon the low levels of blight resistance to make an American chestnut that can compete in the forest.
Griffin developed a scale for assessing levels of blight resistance, which made it possible to make selections scientifically. He inoculated five-year-old chestnuts with a standard lethal strain of the blight fungus and measured growth of the cankers. Chestnuts with no resistance to blight make rapid-growing, sunken cankers that are deep and kill tissue right to the wood. Resistant chestnuts make slow-growing, swollen cankers that are superficial: live tissue can be recovered under these cankers. The level of blight resistance is judged by periodic measurement of cankers.
Grafts from large survivors of the blight epidemic were evaluated following inoculations, and controlled crosses among resistant Americans were made beginning in 1980. The first all-American intercrosses are planted in Virginia Tech's Martin American Chestnut Planting in Giles County, VA, and in Beckley, WV. They were inoculated in 1990 and evaluated in 1991 & '92. Nine of them showed resistance equal to their parents, and four of these had resistance comparable to hybrids in the same test.
It appears that inheritance of resistance requires genes of two trees with good combining ability from each source location. Thus, more generations of controlled crosses will be required to make American chestnuts produce blight resistance that is regularly inherited by seednuts. It takes at least 7 years for an American chestnut to produce nuts, and new trees must be at least 5 years old before their resistance can be tested by inoculation; the test requires 2 years for evaluation. Some of this time may be saved by utilizing grafts, and further progress may result from Elkins' studies underway, to locate chemical markers for resistance. In the meanwhile, ACCF plantings of all-American intercrosses are producing, from open pollinations, large nut crops.
The potential for significant blight resistance to be randomly expressed in these nuts encouraged formation of the ACCF, to carry on the all-American breeding program and enlist the help of cooperating growers to raise these nuts and report their progress to a central data base.
To join our work, please write: ACCF, 2667 Forest Service Road 708, Newport, VA 24128
Send ACCF e-mail to Lucille at Lucille@accf-online.org
***For more information follow the links below***
American Chestnut Cooperators Foundation Online
American Chestnut Cooperators Foundation
A Tennessean's Version of an American Chestnut Page