More than 400 sprouted seeds from an experimental hybrid of the American and Chinese chestnut trees were planted on a hilltop at the Trexler Nature Preserve on Sunday, April 15.
The plantings were a cooperative project of Lehigh County, the Wildlands Conservancy, the PA-DCNR, and the American Chestnut Foundation - Pennsylvania chapter.
The planting of the experimental orchard is an offshoot of a long-term breeding program between American and Chinese chestnut trees. The American chestnut was the keystone species in American forests until the turn of the last century, when the chestnut blight fungus arrived from Asia and swept through the eastern United States.
By 1950, the American chestnut was virtually extinct. Today scientists, volunteers and landowners are working to develop and breed blight-resistant American chestnuts and restore them to their native range.
"After generations of interbreeding and selection, the chestnuts that have been planted will show whether this intermediate generation has enough resistance to survive long-term in a reforested site," said Sarah Fitzsimmons of the American Chestnut Foundation.
The American chestnut tree was a major component of eastern forests, making up 25 percent of Pennsylvania forests. It produces high-value timber because it is fast growing, tall, and extremely rot resistant. Its nuts are valuable to wildlife and people. Its tannins were used in tanning leather
A chestnut blight was introduced through the importation of chestnut trees from Asia that were resistant to the fungus. Once introduced, the blight traveled 20 to 50 miles a year and, by the 1950s, the blight had spread across the range of the American chestnut, principally along the Appalachian Mountains.
The blight fungus enters the tree through cracks and wounds. It forms a canker and girdles the tree.
The American Chestnut Foundation was founded in 1983 with the goal of restoring the American chestnut tree to its native range within the woodland's of the eastern United States using scientific research and a backcross breeding program.
The breeding program crossed the American chestnut, which was 80 to 100 feet tall but not resistant to blight, and crossed it with the Chinese chestnut which was 40 to 60 feet tall and was resistant to blight.
After six generations of selective crossbreeding, a variation called the BC3F3 seed is available for testing. It contains 93.75 percent American chestnut characteristics and is blight resistant. Three hundred of these seeds will be planted at the Trexler Game Preserve along with 132 seats from three other variations which will be used for control purposes.
Besides the Trexler Game Preserve plantings, orchards have been planted locally at the Francis E. Walter Dam and Blooming Grove.
Before arrival of the 40 volunteers, Lehigh County workers had plowed rows and placed posts along each row. The entire orchard was surrounded by deer exclusion fencing. Each planted seed was covered by a plastic tube to protect it from birds and raccoons.
Fitzsimmons demonstrated how to plant the chestnut seeds. She removed a seed from a plastic bag that was filled with about 100 seeds in peat moss. Each seed had spouted a radical, a forerunner to the root of the plant. She explained that the radical must be planted downward so that the tree will grow straight.
Fitzsimmons explained that the chestnuts like sandy soil, so she dug an inch or two into the soil, scraped the soil to get rid of clumps of grass, placed the seed into the hole, radical facing down, and covered the hole with dirt and mulch.
The results of the experiment is likely to suggest that either the current variation needs further development or that it is has sufficient characteristics of the American chestnut tree and sufficient bright resistance to be propagated in large numbers and replanted in American forests.
"Our vision is that someday you will walk through the woods and see trees that look like the American chestnut that are resistant to the blight," said Fitzsimmons. "Trees that are seeding prolifically and reproducing so that their grand-trees are surviving and regenerating themselves in the forest."