A century ago, 20% of the trees in the Appalachian forests were American chestnuts.
The nuts were rich in protein and oils, so early settlers left mature chestnuts to produce nut crops for both people and pigs. When harvested, the
chestnut wood was easy to split and highly-resistant to rot. Even today, there
are skeletons of 70-year old chestnuts on the ground in Shenandoah National Park, still
resisting decay.
But the tree could not resist Cryphonectria parasitica (previously known as Endothia parasitica), a fungus common in China. In 50 years, after being accidentally introduced to America, the fungus spread throughout the Appalachians and essentially eliminated the American chestnut.
Today in Virginia, where do you think a non-native plant might arrive first? Odds are that an accidental import would appear first in a nursery, as an unwanted "bonus" imported along with the intended species. If not there, then perhaps a new import would come into Virginia at the Dulles airport or the docks at Norfolk.
Perhaps the recovery of the chestnut will begin in Abingdon. There - in Meadowview, Virginia, to be specific - the American Chestnut Foundation has the Wagner and Price research farms stocked with thousands of chestnut trees.
Sick chestnut trees. Trees infected with the fungus. In most cases, trees that will be burned, not replanted in the forests to start the restoration of the American chestnut in the wild.
In the natural environment, native American chestnuts get infected by the fungus after several years. Presumably fungal spores get through the protective bark after the branches of the saplings reach a certain size and create fissures in the bark, or naturally-caused wounds (ever listen to tree branches rub against each other during a storm in the woods?) open up an avenue for infection. The fungus grows under the bark, blocking the flow of water and nutrients from the roots and killing the sapling. Usually the trees die before they mature enough to produce nuts.
If the American Chestnut Foundation assumptions are correct, two or three genes determine if a tree is resistant to the blight. Efforts to introduce the blight-resistant genes by breeding with Chinese chestnuts has created crossbreeds that withstand the fungus... but look like Chinese rather than American chestnuts. The Chinese species resembles short apple trees, while the American species grew tall and straight, up to 100 feet tall like a tuplip poplar today in the woods. A tree that is over 90% American chestnut (15/16ths genetically) is expected to look like an American tree, but resist the blight like a Chinese chestnut.
If a bioterrorist were to impact our native species in a similar way today, killing 20% of the forest, think the cries for retaliation would be shrill? Perhaps no one would notice. The sad chestnut story is being repeated by the butternut canker. That disease is now killing the butternuts in Virginia. Confederate soldiers dressed in wool uniforms that were dyed a light "butternut brown," but that once-common species will soon be rare.