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. The injured bark was forming a canker—an area of dead tissue. The 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. , 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. There, people depended on the chestnut for food, livestock feed, and timber. In these Eastern forests,
