Restoring the American Chestnut

A test planting is under way at Smith Mountain Lake State Park to see if newly developed potentially blight resistant plants can adapt to the environment.

Story by Jim Gerhart

Friends of Smith Mountain Lake State Park

The magnificent American chestnut tree once dominated 200 million acres of the eastern United States. It was known as the “cradle to grave tree,” as it could grow for 300 years and was used to build both cradles and graves. Chestnuts were a primary food source for wildlife, livestock and people. Roasted chestnuts were sold by street vendors.

Then in the late 1800s a fungal pathogen that causes chestnut blight, arrived from Asia. By 1914, the blight had reached Northern Virginia. By 1925, it was blazing through the Blue Ridge into North Carolina, killing virtually every overstory chestnut tree in its wake and spreading south and west at a rate of 24 miles per year. In a short 40 years, the tiny fungus killed between three and four billion trees. By 1950, nearly all mature chestnuts across the Eastern United States were gone.

For many years, various ways to bring back the American chestnut were explored. In 1983 a dedicated group of scientists founded The American Chestnut Foundation (TACF). In 2009 TACF announced the first planting and testing of seeds which were potentially blight resistant. Additional breeding and development is under way and now Smith Mountain Lake State Park has been selected as a planting site.

The Dominant Species of the Forest

The American chestnut Castanea dentate, was once one of the most important trees in eastern United States. 25% of the trees in the Appalachian forests of Virginia were American chestnut. The American chestnut grew slowly as an understory tree, waiting for a storm or other event to create a natural clearing for sunlight. Once the sapling was in direct sunlight it could grow very large and fast, exceeding the height of nearby oaks and maples. It became the dominant tree in many areas. In the early summer their canopies were filled with creamy-white flowers; the mountains appeared snow-capped. Because the flowering occurred well after frost, the nut production was very predictable and abundant. The wood was used for virtually everything – telegraph poles, railroad ties, shingles, paneling, fine furniture, musical instruments, even pulp and plywood.

The chestnut has a prickly burr which houses 3 chestnuts

The Chestnut Blight Strikes!

The first warning signs came in 1904 when rust-colored cankers developed on chestnuts at the Bronx Zoo in New York. The spores were soon identified as Cryphonectria parasitica a chestnut blight. The blight probably hitched a ride on nursery imports of Japanese chestnuts beginning in 1876. Asian trees stopped growing at about 40 feet, while American chestnuts grew to 80-100 feet, so orchardists were importing Asian species and trying to create commercial farms using the easier-to –harvest Chinese and Japanese chestnuts.

Spreading through rain, birds and air, fungal spores which were common in China and Japan infected trees through bark wounds and breaks. Cankers developed (see photo), quickly encircling a branch or trunk and cutting off the supply of water and nutrients from the soil. The Asian version of the chestnut tree could resist the fungus, but the American chestnut’s response was too slow to stop the invasion.

The American chestnut is not an endangered species, or threatened with extinction. There are millions of small, young chestnut sprouts. Above the site where the tree has been girdled by the fungus, an American chestnut will die. Below the infection site, the chestnut tree’s roots usually survive, so the roots can resprout. A young chestnut tree matures until a crack in the bark allows a new infection, and the cycle repeats itself - which is why we still see small chestnuts growing in Virginia forests.

Today the chestnut is a minor component of the understory, no longer a dominant species that affects the surrounding forest.

Restoring the Mighty Giants

For many years scientists have been searching for ways to bring back the American chestnut, which has such a storied history and important part of everyday life for millions of people almost a century ago. Three different options are currently being pursued:

· Finding the few naturally-resistant trees still surviving in the woods, with American chestnut genes, then growing new stock from their nuts and grafts to ensure the resistance is transmitted to future generations.

· Using the latest laboratory techniques to insert blight-resistant genes, developing a genetically-modified organism.

· Breeding a blight-resistant hybrid tree, mixing genes of the Chinese chestnut species with the American chestnut.

The cross breeding technique currently has shown much progress and promise in developing a blight resistant American chestnut tree.

Breeding an American/Chinese Hybrid

In 1983 a determined group of plant scientists joined together to form The American Chestnut Foundation (TACF), with the goal of restoring the American chestnut to the eastern forests. Much of the work takes place at their Meadowview research farm, near Abingdon, Virginia.

Seven generations of chestnuts have been raised since the 1980s. Volunteers and staff working for the Foundation climb mature trees, to gather the male pollen from specific trees and bag female flowers to isolate them from wild pollen. The volunteers go back up again to pollinate the female flowers with pollen from specific desired father trees, so the tree will grow a nut with genes from pre-determined parents. After a summer of growth, the nuts are harvested by volunteers/staff who go up the tree a third time. By interbreeding (backcrossing) offspring with various American chestnut parents, TACF has produced a final genome that is 15/16ths American and 1/16^th Chinese, including the all-important genes for blight resistance from the Chinese ancestors but showing other characteristics (such as height at maturity) from the American ancestors.

Current plans are to establish numerous stands of “new” chestnuts throughout the Appalachians, by planting trees in test plots which are carefully planned and tracked.

Male Flower Female Flower Bagged Female Flower

Smith Mountain Lake State Park

Brian Heft, Park Manager, Smith Mountain Lake State Park said he learned of the TACFs efforts to reestablish the American chestnut in our area from District Resource Specialist Reed Stanley. They looked at park sites and found one that had the soil type and other factors making it a good location for testing the new strain of American chestnut. He offered the site in the hope that the tree could be established in the park and ultimately provide an abundant supply of chestnuts for wildlife. “Some site preparation is under way, removing stumps and grading. It will be ready for planting in the spring,” he said. The Friends of Smith Mountain Lake State Park and Master Naturalists will be helping with the planting.

Matt Brinkman, Mid-Atlantic Regional Science Coordinator, The American Chestnut Foundation, who is overseeing the planting project said, “There will be about 400 seedlings available for planting. They are the most advanced strain available which is 15/16 American chestnut and 1/16 Chinese chestnut.” Brinkman said that the seedlings will be bare root and have cages to prevent browsing. The nuts producing the plants were harvested at the American Chestnut Foundation’s Meadowview research farm. The seedlings were grown at the Virginia Department of Forestry Center near Charlottesville. He said that the plants all contain different parentage with slightly different levels of resistance. Overall, the average resistance of all those lines and parents is moderate. Brinkman said that as they identify weak parents over the next 5-10 years through analyzing test plantings of their children (the generation at SML) they should be able to increase the overall average resistance. He said that he hopes this planting site, which is the first in a Virginia State Park, will give the managers and local volunteers some experience with American chestnut restoration techniques which sets the stage for larger, more successful projects in the future. Secondly, it serves as a place where individuals, students, etc. can go to see American chestnuts and learn about their historical importance.

Caged American chestnut seedling

Many scientists feel that we have started to pull the American chestnut back from the brink of extinction. Although it will likely be several decades before large quantities of American chestnuts once again populate our eastern forests, the future is beginning to look much brighter for “The Mighty Giant.”

Resources

Photographs obtained from The American Chestnut Foundation

The American Chestnut Foundation

Chestnuts in Virginia; virginiaplaces.org

American Chestnut Restoration Project; The Return of the American Chestnut, Compass, July 2008, U.S. Forest Service

Pursuing an American Dream, Virginia Wildlife, Virginia Department of Game & Inland Fisheries

Forestry in Virginia, Department of Conservation & Recreation

For more information on the Friends of Smith Mountain Lake State Park, go to www.smlspfriends.com.

American Chestnut Planting


Matt Brinkman, who is overseeing the planting project explains the different strains of American chestnuts in the bags to be planted.	Friends of Smith Mountain Lake State Park member, Janis Erickson, staking a predator guard.

Volunteers waiting for lunch.	Friends of Smith Mountain Lake State Park member, Patti Gerhart planting a seedling.