canker
a plant disease characterized (in woody plants) by the death of cambium
tissue and loss and/or malformation of bark, or (in non-woody plants) by the
formation of sharply delineated, dry, necrotic, localized lesions on the
stem; "canker" may also be used to refer to the lesion itself,
particularly in woody plants
(zonate canker caused by Nectria galligena on apple)