What actually happened to the American Chestnut

Over a century ago the American Chestnut (Castanea dentata) dominated the eastern half of the United States. Nearly 4 billion of the trees were thriving.

They were among the largest, tallest, and fastest-growing trees in the United States. The wood was rot-resistant, straight-grained, and suitable for furniture, fencing, and building. The nuts fed billions of wildlife, people and their livestock.

The tree was a staple in American culture until the early 20th century when a fungus was introduced. The chestnut blight has been called the greatest ecological disaster to strike the world’s forests in all of history.

The decline of the American Chestnut

In 1904 an Asian bark fungus, Cryphonectria parasitica, was discovered at was then the New York Zoological Park and is now called the Bronx Zoo. The disease, commonly called Chestnut blight, was accidentally introduced into North America on imported Asiatic chestnut trees. The man who first discovered the blight, Hermann Merkel, estimated that by 1906 the blight had infected 98 percent of the chestnut trees in the borough.

Chestnut blight is an airborne fungus and spread 50 miles a year. As a wound pathogen, the fungus enters the tree through an injury in the bark. It spreads to the underlying vascular cambium and wood, killing these tissues as it advances. The flow of nutrients is eventually choked off to and from sections of the tree above the infection, killing the tree above ground. By 1950, the fungus had eliminated the American chestnut as a mature forest tree.

Salvage logging during the early years of the blight may have unwittingly destroyed trees that had high levels of resistance to this disease. New shoots often sprout from the roots when the main stem dies, so the species has not yet become extinct. However, the stump sprouts rarely reach more than 20 feet high before the blight returns.

Surviving specimens

Although the species is nearly extinct, there are pockets of American chestnuts located outside its native habitat. The largest of which is a pocket of 2,500 chestnut trees growing on 60 acres near West Salem, Wisconsin.

 These trees are the descendants of those planted by Martin Hicks, an early settler in the area, who planted fewer than a dozen trees in the late 1800s. However, in 1987 scientists discovered blight within the stand and have been working to try and save the trees.

Revitalizing the American Chestnut

Several organizations are attempting to breed blight-resistant chestnut trees. The American Chestnut Cooperators Foundation breeds surviving American chestnuts, which have shown some native resistance to blight, and the Canadian Chestnut Council is attempting to reintroduce the trees in Canada, primarily in Ontario.