1. a disease of the bark and cambium that causes a usually well-defined sunken or swollen necrotic lesion —note 1. there are several forms of canker based on shape, position of occurrence on the bole, and whether produced in one year or several —note 2. important canker diseases include chestnut blight (Cryphonectria parasitica), hypoxylon canker of aspen (Hypoxylon mammatum), and beech bark disease (Nectria sp.) 2. a malformation of a host stem or branch caused by a disruption of the cambium as a result of dwarf mistletoe infection 3. a scar left after canker disease or environmental injury This definition last updated 10/25/2008