Septoria leaf spot causes angular lesions with black speck-like fruiting bodies on the upper leaf surface. This disease commonly occurs in late summer or fall. Neither of these fungal diseases attack twigs or branches, and neither have any major impact on tree vigor. A spring leaf blight may occur following bract infection by the fungus Botrytis cineria . If Botrytis infected bracts come into contact with young leaves, infection of those leaves may occur, resulting in symptoms similar to anthracnose.
Powdery mildew is another disease that can mimic anthracnose.
Severe mildew infection can cause leaf blight and twig dieback. Leaf scorch due to drought, or other noninfectious root stress problems can also resemble symptoms of dogwood anthracnose, although foliar symptoms due to noninfectious causes usually form a more uniform pattern on the leaf. Confirmation of Dogwood Anthracnose Dogwood anthracnose can be difficult to diagnose. Several branches with symptomatic leaves or twigs should provide enough diseased tissue to make an accurate diagnosis. No single practice can insure complete control of dogwood anthracnose.