Cryptosporiopsis canker

Cryptosporiopsis spp. red

Red maple cultivars 'October Glory' and 'Autumn Flame' are most susceptible to this disease. Young cankers are elongate, slightly sunken, gray lesions, and they occur often on stems less than 10 cm in diameter. Most cankers have a single, tiny (1 mm diameter) hole in their centers, and sap may ooze from these holes, especially in early spring. The holes are made by female narrow-winged tree crickets during egg laying. Apparently, the crickets introduce the fungus into these holes, and disease occurs thereafter. Callus usually forms around margins of cankers one year after infection, and the fungus is contained therein.