|Us trees can get sick from bacteria, viruses, fungi, and other stuff. The American chestnut tree blight was caused by a rampant fungus. The microscopic fungal spores are spread effortlessly, carried on the wind, by birds, insects, and even humans.
The fungus then enters our trees through small cracks and wounds in our bark. From there, the fungus spreads threadlike strings that penetrate our vascular system, blocking the food pathways. When cankers have formed all the way around the trunk like a belt or tourniquet, the upper part of the tree dies almost overnight. The leaves wither and turn brown as they starve from lack of water.
Because the fungus cannot grow below the ground, the American chestnut's roots continue to grow new stems when the old shoots die. Sadly, the new sprouts are doomed; they will eventually become infected and die.
The chestnut blight or fungus is also known by it's scientific name: Cryphonectria parasitica.