Cryphonectaria parasitica

Cryphonectaria parasitica is a fungus that causes chestnut blight, a disease that devastates American chestnut trees. Originally from Asia, this pathogen was introduced to North America in the early 1900s, leading to significant declines in the chestnut population. The fungus infects trees through wounds and spreads quickly, forming orange-brown cankers that girdle and kill branches and eventually the entire tree. This has had a profound ecological impact, as the American chestnut was once a dominant tree species in eastern forests. Efforts are ongoing to develop resistant chestnut varieties and restore the species.