About Mycosphaerella fraxinicola (Schwein.) House
Scientific name: Mycosphaerella fraxinicola (Schwein.) House. The leaf spots caused by this organism begin as irregularly shaped, pale green lesions. As the disease progresses, the spotted tissue rots and turns black. Individual spots range in size from 5 to 15 mm (0.2 to 0.6 inches) across.