Under continuously wet conditions, an entire plant may die. The distribution and severity of the two diseases is not yet known. The symptoms are identical for the Phomopsis and Kabatina twig blights, but the Cercospora twig blight is different. The Cercospora infections start on the oldest foliage on lower branches and the blight spreads upward. The branch tips usually remain healthy and green.
Early symptoms occur on the leaves of the spur branches.
The leaves brown at the tip, then become entirely brown and die. This foliage usually dies in late summer and the affected spur branchlets fall off in the fall, leaving a plant with an inner crown devoid of foliage. On the infected brown leaves, small, dark fruiting bodies form and produce the spores that cause new infections of the previous years' spur leaves. Wet weather is needed for spores to infect foliage, and the longer foliage remains wet, the more disease develops. The spores are produced from spring through fall, but most infection occurs in summer in some years and in late summer other years.