Apple valsa canker is characterized by elongated cankers on trunks and scaffold limbs or dieback of twigs. The disease first appears on the branch surface as brownish oblong spots with irregular edges. The infected tissues then gradually dry out, slightly sunken, more or less darkened, and finally form localized cankers. The canker develops rapidly between spring and early summer, and then slowly during the late summer and in the winter. With the perennial development of cankers, they girdle twigs, branches, and trunks, which lead to desiccation and death of the distal part, even the entire tree.