UT, Smokies partner to restore American chestnut tree
By Joel Davis | (joeld@thedailytimes.com)
The University of Tennessee and Great Smoky Mountains National Park continue to help in the quest to restore the American chestnut.
Both UT and GSMNP partners with the American Chestnut in different ways. UT also participates in independent research on battling the chestnut blight and other pests of the once-common trees.
Once a major part of the American landscape, uncounted numbers of chestnut trees were killed in the first half of the 20th century after the accidental introduction of the blight fungus from overseas.
The American Chestnut Foundation is now working to achieve blight resistance through hybrid trees crossed with blight-resistant Chinese chestnuts. Successive generations are then bred with American chestnuts to retain the main characteristics of American trees.
“The park has worked closely with the American Chestnut Foundation on the research and development of some of the options for the future,” said Jesse Webster, GSMNP forester.
The National Park Service has a memorandum of understanding with the ACF for research and development. Genetic material from remaining chestnut trees in the park has been used for research.
Chestnut trees are not actually extinct in the park. There are thousands of remaining stumps within GSMNP borders, which continue to produce sprouts that can grow into sizeable saplings. However, the chestnut blight fungus still lurks in the soil and air and eventually kills the trees.
Researchers at UT’s Tree Improvement Program have been evaluating how test plantings of American chestnuts in the region fared during this year’s long growing season.
Evaluating hybrids
UT scientists and Stacy Clark, Ph.D., of the U.S. Forest Service are evaluating hybrids, which are 15⁄16 American chestnut and believed to carry blight resistance from the Chinese parent. Clark, who worked with the UT Tree Improvement Program while earning her master’s degree, is based in Knoxville at the UT Institute of Agriculture.
UT scientists, led by Scott Schlarbaum, Ph.D, a professor in the Institute of Agriculture’s Department of Forestry, Wildlife and Fisheries, are evaluating the trees, which were produced by three American chestnut breeding programs.
Researchers are using a virus that infects the chestnut blight fungus itself.
Trees infected with virus-treated fungus have managed to heal over cankers caused by the blight, enabling trees to fight the disease.
The virus has been found to occur naturally in some trees, among them a small stand of 30-year-old American chestnuts growing on land used for agricultural studies by scientists with UT AgResearch.
No wholesale return
The push to achieve blight-resistant and robust chestnuts is to restore Eastern forest ecosystems and thus reintroduce an important food source to wildlife as well as grow rot-resistant timber, but Schlarbaum is not predicting a wholesale return of the tree.
Test plots of seedlings believed to be blight-resistant and which are now growing at undisclosed locations in southern national forests were evaluated for growth, survival to blight and response to disease and insect problems.
The first series of plantings was initiated in 2009, and subsequent growth has been spectacular in some of the seedlings, but scientists are finding the plantings are not without problems.
In the absence of American chestnuts, Chinese and some of the Asian chestnut trees can be good both for human and wildlife consumption.
An experiment conducted in the 1990s by scientists and undergraduates at UT found that wild turkeys recognized American and Chinese chestnuts as food, even after the chestnuts’ long absence.
The turkeys preferred smaller chestnuts to larger ones, which can approach two inches in diameter. In terms of preference, the turkeys ate chestnuts as often as white and red oak acorns.
