By Leila Javitch
It looks likely that in the not too distant future the almost extinct American Chestnut may return to the forests of Connecticut. This has come about by advances in the science of cross breeding, and perseverance and voluntary work by members of the American Chestnut Foundation, 40% of whom live in Connecticut.
Norfolkís Great Mountain Forest is now host to a 2007 spring planting of hybrid seedlings that have been back bred and cross bred to be resistant to the fungus that wiped the trees out in the first place.
The American Chestnut was once the stately giant of our forests, thriving from Maine to Georgia. It is estimated that one out of every four trees was a chestnut. The trees, some over 100 feet tall, grew strong and straight and were resistant to rot, making the wood a highly valued timber. It was used for utility poles, railroad ties, and fencing as well as floors, paneling and load-bearing house frames.

Illustration by Leslie Watkins © 2007

The fruit, the chestnut, was an abundant source of food for wildlife as well as a popular and nutritious protein for humans. The blight struck in 1904 when a few ìexoticî chestnuts, probably imported from Japan, were brought to New York. They carried a fungus that Asian Chestnuts were resistant to, but American Chestnuts were not. In the next 50 years, except for the sprouts the chestnut produces, the tree was wiped out.
There have been many attempts to breed a new resistant chestnut, and Connecticut in fact has the longest continuous breeding program in the United States. However, early attempts, mainly random crosses to hit upon the one perfect tree, were not successful. Now, more genetic knowledge and modern methods have yielded promising results.
The process involved is a combination of back and cross breeding. Here is how it works. Chinese Chestnuts are genetically resistant to the virus, but cannot replace their American counterpart because they are much smaller and scrubbier, shaped rather like an apple tree. They have little value as timber. Moreover, they do not adapt to the various forest environments in the United States. The trick is to blend the virtues of each, and to choose a local parent tree that is indigenous to the area where the seedlings will grow so that the progeny has the best chance of survival.
To do this, a surviving American Chestnut is initially cross pollinated with a Chinese Chestnut that has proved resistant to the fungus organism. The product of this breeding, which usually takes about six years, is then repeatedly back crossed again with the parent American Chestnut. In these crossings the seedlings that result are inoculated with the virus. Only those specimens that donít show signs of damage are bred again. Finally the back bred seedling is cross bred with another of its generation. The final seedling is 15/16ths or 93.75% American Chestnut but also resistant to the deadly fungus, thanks to the initial infusion of the Chinese treeís genetic protection.
The orchard now growing in the Falls Village side of the Great Mountain Forest was planted in May 2007. 118 chestnuts–the result of four generations of breeding–were supplied by the American Chestnut Foundation. They appear to have germinated well. The nuts were placed in protective tubes when planted; the tubes are about two feet high. Some of the seedlings are already surfacing at the top of the tubes because the American Chestnut grows rapidly. Soon, deer fencing will be necessary to protect the tender leaves. The chestnut seedlings definitely need careful maintenance. At the Great Mountain Forest, Forester, Jody Bronson and Wood Sinclair, a volunteer member of the American Chestnut Foundation, watch over these seedlings. With the time needed to successfully complete back and cross breeding, producing a chestnut becomes a lifelong endeavor. Those interested in participating in this worthy effort should contact the Connecticut branch of the American Chestnut Foundation.