If the American chestnut tree is not soon restored to American forests, it won't be for want of trying.
These trees once covered most of the eastern half of the United States, growing from Maine to Minnesota and south to Florida and Mississippi. They were valued for the high quality of their wood and for the nuts.
Around 1900 a fungus disease, Endothia parasitica, came to the United States on trees from Northern China. In less than 25 years it killed most of the American chestnut trees on the Eastern seaboard.
Today there are a few chestnut trees in the Midwest of timber size that produce nuts but they have no resistance to the disease.
The blight has not yet reached them because prevailing winds are westerly, according to specialists.
The Chinese chestnut is relatively blight-resistant but cannot nearly match the wood-producing quality of the American chestnut. Chinese chestnuts are a little larger but do not have the sweet flavor of the American.
The fungus kills by destroying the tree's cambium or growing layer. In order to do its destructive work, the fungus must get into a crack or wound in the bark of the tree.
In the growing process, cracks appear naturally in the bark of older trees and they become vulnerable.
The disease doesn't kill the roots of the trees and young trees conttinually sprout from the roots. When the bark of the young tree splits, the disease sets in, the tree dies, young trees sprout from the roots, and the cycle goes on and on.
West Virginia scientists are trying to produce plantlets by growing American chestnut tissue in test tubes. Cells from young healthy trees are placed on a food source containing vitamins, minerals and other elements needed for growth.
"The cells are multiplying well," says Dr. Franklin C. Cech, West Virginia University professor of forest genetics. "We are beginning to vary the compounds of the food supply to cause these cells to change into the various cells that make up roots, leaves and other parts of a tree."
Thousands of nuts (seed) from young trees in several states have been collected and planted during the past 50 years in the hope of developing a resistant seedling. So far none-has been found.
In Maryland, Stronghold Inc., a private group dedicated to restoration of the chestnut, has been using radiation in the hope of speeding the process of mutation so that a seed will evolve with resistance to the blight.
In 1956 the first chestnuts were irradated in the reactor of the Brookhaven National Laboratory. By 1974 more than 10,000 first-generation trees were growing in five states - Maryland, Virginia, West Virginia, Ohio and Pennsylvania.
As early as 1972 some of the first-generation trees were producing seeds. In 1973, more than 830 chestnuts were harvested.
These chestnuts are being planted in the hope that the second generation will produce a mutation with disease resistance.
Recently at the West Virginia Agricultural Experiment Station, Lignosan (a new fungicide essentially the same as the one that has been cleared by the Enviromental Protection Agency for treatment of Dutch Elm Disease) was tested on diseased American chestnut trees. It was found the tree could be protected and small infections arrested with this material.
However, this technique is not practical for wide-scale use because of the high cost.
Progress has been made in developing hybrid chestnuts of good form and blight resistance but much remains to be done to obtain a true breeding forest tree. The best trees to date are single tree selections, which are difficult to reproduce from cuttings or by grafting.
There is hope now that a method has been found to cure the disease.
In France, European chestnut trees dying from the disease started to make a comeback. Research showed that a new and weaker strain of the fungus was inhibiting growth of the Asiatic strain. Trees with blight began to get well.
Dr. Richard A. Jaynes, geneticist, Connecticut Agricultural Experiment Station, New Haven, imported the new strain and found it worked on the American chestnut also.
Now it must be determined whether the new fungus will spread itself or whether man will have to do it.