The
pathogenic fungus
Cryphonectria parasitica (formerly
Endothia parasitica) is a member of the
Ascomycota (sac fungi) taxon, and is the main cause of
chestnut blight—a devastating disease of the
American chestnut tree that in the early 1900s caused a rapid, widespread die-off of this once plentiful tree from its historic range in the eastern United States.