Slightly before the turn of the century the Cryphonectria parasitica, reduced the American chestnut from its position as the dominant tree species in the eastern forest to little more than an early-succession-stage shrub.
Abundant Lumber No More
There has been essentially no chestnut lumber sold in the United States for several decades and the bulk of the annual 20-million-pound nut crop now comes from introduced chestnut species or imported nuts.
American Chestnut Has Not Gone Extinct.
The species has survived. The most recent USDA Forest Service survey for New York State indicates that there may be as many as 60 million of these sprout clumps in New York State, a rich gene pool for starting a restoration effort.
Chestnut blight, a plant disease caused by the fungus Cryphonectria parasitica (formerly known as Endothia parasitica). It killed virtually all the native American chestnuts (Castanea dentata) in the United States and Canada and also is destructive in other countries. Other blight-susceptible species include Spanish chestnut (C. sativa), post oak (Quercus stellata), and live oak (Q. virginiana). In Europe several oak species are affected.
Accidentally imported from the Orient, the disease was first observed in 1904 in the New York Zoological Gardens. By 1925 it had decimated the American chestnut population in an area extending over 1,000 miles (1,600 km) north, south, and west of its entry point. Symptoms include reddish brown bark patches that develop into sunken or swollen and cracked cankers that kill twigs and limbs. Leaves on such branches turn brown and wither but remain attached for months. Gradually the entire tree dies. The fungus persists for years in short-lived sprouts from old chestnut roots and in less susceptible hosts. It is spread locally by splashing rain, wind, and insects; over long distances, by birds. Chinese (C. mollissima) and Japanese (C. crenata) chestnuts are resistant. Crosses between American and Asian species have produced varieties with excellent nuts, but timber quality is closely linked with blight susceptibility. In the 1970s a native American strain of chestnut blight was identified. Experiments indicated that the native strain was less virulent than other strains and that it had a nullifying effect on lethal strains. Unfortunately, the mild strain of blight does not readily spread from tree to tree among American chestnuts.