There may be a faint yellow halo around the spot.
More lesions develop low in the tree.
Leaves fall prematurely and twig death may occur due to defoliation. The fungus survives on trees in old leaf lesions that have a white, crusty appearance. The margins of these lesions enlarge in fall and a new crop of spores develops there. High temperatures restrict spore germination and growth, thus the disease is inactive during the warm, dry summers in California. Once this disease occurs on trees, it is important to treat for it yearly.