What Happened?American chestnut was once the most important tree of the Eastern North American hardwood forest. One fourth of this forest was composed of native chestnut. According to a historical publication "many of the dry ridge tops of the central Appalachians were so thoroughly crowded with chestnut that, in early summer, when their canopies were filled with creamy-white flowers, the mountains appeared snow-capped." The nut was a central part of eastern rural economies. Communities enjoyed eating chestnuts and their livestock was fattened by the nut. And what wasn't consumed was sold. Chestnut was an important cash crop for many Appalachian families. Holiday nuts were railed to New York and Philadelphia and other big cities where street vendors sold them fresh-roasted.
The tree was a major lumber producer. Not too long ago, the American chestnut was one of the most important trees of forests from Maine south to Florida, from the Piedmont west to the Ohio valley. In the heart of its range only a few generations ago a count of trees would have turned up one chestnut for every four oaks, birches, maples and other hardwoods..
A chestnut disease was first introduced to North America through New York City in 1904. This chestnut blight, caused by a fungus and presumably brought in from eastern Asia, was first found in only a few trees in the New York Zoological Garden. The blight spread with a vengeance and in its wake left only dead and dying stems.
By 1950, Castanea dentata had disappeared except for shrubby root sprouts the species continually produces (and which also quickly become infected). Like many other pest introductions, blight had quickly spread into its new - and defenseless - host causing wholesale destruction throughout the entire range of the chestnut.
For decades, plant pathologists and breeders tried to create a blight-resistant tree by crossing our own species with the resistant Chinese chestnut and other chestnut species from Asia, but always with unsatisfactory results. Now, advances in our understanding of genetics have shown us where those early researchers went wrong.