Cryphonectaria parasitica is a fungal pathogen known for causing chestnut blight, a disease that severely affects American chestnut trees. This fungus invades the tree's bark, leading to cankers that disrupt the tree's ability to transport nutrients and water, ultimately resulting in tree death. Originally introduced to North America from Asia in the early 1900s, Cryphonectaria parasitica has devastated chestnut populations, which were once a dominant species in eastern forests. Efforts to combat the blight include breeding resistant tree varieties and exploring biological control methods to restore the chestnut's presence in its native habitat.