Fig. 1. An American chestnut stem with a chestnut blight canker (Castanea
dentata with a Cryphonectria parasitica canker). The fungus enters
through wounds such as the broken branch stub on the left, and grows in and
under the bark, killing the cambium. Fungal stromata break through the lenticels
and pycnidia producing conidia and perithecia producing ascospores are formed.
Photo by R. A. Jaynes.