Bringing Back the GAINTS

Scientific Efforts To Restore The American Chestnut Tree

- Carolyn Fay

Chief forester Hermann Merkel was worried. In the summer of 1904, he noticed areas of cracked, dry bark on the American chestnut trees in New York Zoological Park (known today as the Bronx Zoo). Tiny orange-red bumps dotted the bark like an angry rash. e injured bark was forming a canker—an area of dead tissue. e canker would eventually encircle the trunk and strangle the tree. Merkel suspected it was a fungus, but not one he’d ever seen before.

Merkel was right to worry. Cryphonectria parasitica, also known as the chestnut blight, ended up killing an estimated four billion American chestnut trees. It was a devastating loss, especially in the Appalachian Mountains. ere, people depended on the chestnut for food, livestock feed, and timber. In these Eastern forests, American chestnuts were giants, growing as tall as 100 feet (30 meters), with trunks 13 feet wide (four meters). Some were at least 600 years old.

How could a fungus kill so many trees? Cryphonectria parasitica is not native to North America. It likely came to the US as a stowaway on imported Japanese chestnut trees. Japanese and Chinese chestnut trees often survive the blight. Scientists call this “blight resistance.” Because Asian chestnuts evolved alongside of Cryphonectria parasitica, they had thousands of years to adapt to it. When the fungus invaded the bark of one of Merkel’s trees—likely through an animal’s scratch or an insect’s burrowing—the American chestnut had no defense.