How Did It Get To The US?
In 1904, the chestnut blight was mistakenly brought to the United States. Chestnut bark disease (Cryhonectria parasitica) was first reported in New York City on American Chestnut trees. The suggestion was made that diseased Japanese chestnut trees were the cause of the introduction. This was later verified as correct and Japanese as well as some Chinese trees have a strong resistance to the fungus.
How Does The Fungus Work?
The chestnut blight shows itself by forming orange-colored splits in the bark of the trunk and branches, interrupting the flow of soil nutrients going up the tree. Because these soil nutrients strengthen the roots, the tree sprouts over and over in the same spot. Although, chestnut sprouts rarely make it to be more than a few inches in diameter before the disease infects them again.
What Efforts Are Being Taken To Counteract The Disease?
The primary method of controlling the Chestnut Blight is to introduce a counter-virus called hypovirulence. Although hypovirulence spreads slowly compared to the blight, it has proven many times to cause remission of the disease. The counter-virus slows the spread to the blight so the tree may become resistant to the fungus before it dies.