Leafspot on Oakleaf Hydrangeas
Oak leaf hydrangea can get a couple of different leaf spot diseases, and in wet, cold springs they can be more noticeable. As growth continues it will be less of a problem.
This plant is a tough native and we would not recommend any treatment.
In most cases, leaf spotting diseases will not threaten the health of shrubs. If it makes them feel better, spotted leaves can be removed on a dry day and put in the trash. Mature shrubs can be thinned for better air circulation. Rake and remove infected fallen leaves in the fall and plant resistant varieties when available.