Anthracnose

I noticed I have anthracnose on my oak leaf hydrangeas. I took a picture of one of the leaves that display the most symptoms. Anthracnose fungi thrive in cool, moist environments (commonly experienced in the spring). The leaves that have emerged since earlier in the season are not displaying symptoms.

Anthracnose is a general term for a variety of fungal diseases that affect numerous plants. (Different species of fungi infect different plants.) Symptoms on leaves include brown or black spots, or numerous specks. If leaves are badly infected, they can die and fall off. Although symptoms are most common on leaves, antracnose can occur on other parts of the plant (including fruit).

To minimize anthracnose on your plants, promote air circulation by pruning your trees and shrubs. Also, clean up infected leaves and dispose of them to minimize re-infection when the conditions become favorable once again.