In Colorado it affects mainly peaches and apricots, and to a lesser degree sweet cherries. Severe foliar shot holing may weaken a tree, while the most apparent damage is infection of the fruit. The fungus apparently overwinters in dormant infected leaf buds, blossom buds and small twig cankers. Spore production begins in early spring. The first symptoms of infection are observed on young leaves as small red spots that enlarge and become purple with a white center.
Numerous holes give a very tattered appearance to infected leaves.
Economic loss from Coryneum blight results when peach or apricot fruit are affected. The spots or lesions on the epidermis blemish or disfigure the fruit. Spots may appear on the fruit anywhere from 10 to 12 weeks prior to harvest through the post-harvest period. These are similar to damage caused by San Jose Scale, and great care is required to avoid confusion. In severe cases, lesions coalesce and cause skin cracking.