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Chestnut Blight
Chestnut Blight Strikes!
First identified in 1904 in New York's Bronx Zoological Park, the chestnut blight is caused by an Asiatic fungus (Cryphonectria parasitica) and is almost always lethal to the American chestnut. Moving through the range of the chestnut at a rate of up to 30 miles a year, by the 1950s the chestnut blight had devastated over 200 million acres, killing an estimated 4 billion chestnut trees. The loss of the chestnut is often cited as the worst ecological disaster of the 20th century in the U.S. In fact, because of the unintentional import of chestnut blight, the federal government created the first plant quarantine laws.
How the Blight Kills
Chestnut blight is characterized by blight fungus, which feeds on the cambium tissue under the bark of the tree. The fungus creates cankers that break through the bark, cutting off the flow of nutrients between the leaves and the roots, which kills the tree. Typical cankers on young, smooth-barked trees first appear orange in contrast to the normal green of grey bark. Thick bark on larger trees become cracked and flaking.
Stump Roots
The roots of the chestnut are usually not affected by fungus, and may continue to feed new sprouts that arise from around the base of the tree or stump for many years. These sprouts can sometimes grow 30 feet or more before succumbing to the chestnut blight. Sometimes a fortunate sprout will avoid the blight and grow large enough to produce flowers and seed. |