Cankers develop on main trunk near ground level. These cankers enlarge and girdle the plant. Leaves above the canker turn pale green, then brown, and remain attached for awhile.
Infected bark is brown, and wood beneath is brown or greyish black.
Use of resistant varieties appears to be the most effective method of control. Stem galls, Phomopsis sp. Heavily infected plants may die. No effective controls have been identified. Powdery mildew, Microsphaera penicillata.