Researchers close in on solving American chestnut blight

American-chestnut

The American chestnut once dominated Eastern North America, with the total number of trees estimated at 4 billion a little more than a century ago.

They were the prevailing species in many areas, particularly in the Appalachia region, where 25 percent of trees were chestnuts.

“Entire communities in Appalachia depended on the chestnut for everything,” said Marshal Case, former president of the Asheville, NC-based American Chestnut Foundation. The nonprofit has been leading the effort to re-establish the trees.

Chestnut trees were integral to everyday life in Appalachia and were known as “cradle to grave trees,” Case told National Geographic.

“Craftsmen made baby cradles and coffins from the rot-resistant hardwood. The trees were also used to build houses, telephone poles, and railroad ties,” he said. “Wildlife thrived on the trees, which each year produced bumper crops of nuts.”

The American chestnut was dealt a near-death blow with the introduction of Chinese chestnuts into the New York Botanical Gardens, now known as the Bronx Zoo. The Chinese chestnut brought with it a blight that, while it didn’t affect its carrier, was devastating to the American chestnut.

First identified in 1904, the blight, a fungus, infected and killed about 99.9 percent of the American chestnuts from Georgia to Maine and west to the Ohio Valley within 50 years.

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 in height before blight returns.

The number of large trees surviving over 24 inches in diameter within the tree’s former range is believed to be fewer than 100.

Range of American chestnut around turn of the 20th century.

Range of American chestnut around turn of the 20th century.

The American Chestnut Foundation, working with a variety of scientific institutions, has been involved in decades-long research aimed at restoring the American chestnut.

While significant gains have been made, the breeding of American-type chestnuts that are consistently resistant to attacks by blight and root rot is still a work in progress, according to Clemson University, one of the institutions involved in the research.

“Traditional methods of plant breeding have been recently joined by high-tech genetic mapping techniques that are aimed at revealing the genes that control traits such as blight and root rot resistance,” according to information from Clemson. “The chestnut’s genome is immense, containing about 800 million base pairs. Researchers at Clemson are zeroing in on the specific genes – hidden within a morass of others – that will lead to further breakthroughs.”

One of the goals is to introduce resistance from the Chinese chestnut into the American chestnut.

Arresting the blight, of which at least 50 strains are known and which can travel 50 miles a year, would be a remarkable accomplishment.

Experts believe that a solution is near, but that it will be at least 10 to 15 years before American chestnuts are again growing in stands.

(Top: 50-foot tall American chestnut in Grassy Creek, NC.)

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2 thoughts on “Researchers close in on solving American chestnut blight

  1. We were just on a camping trip in the Grayson Highlands area of the Blue Ridge Mountains here in VA. There was a giant stump with a sign attached explaining exactly what you have about the trees STILL sending up new shoots and still being attacked by that dreadful fungus. So upsetting!!

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