3.  Maple Anthracnose
Irregular, light brown spots of dead tissue appear on the leaf from late May to August. They develop during or just following wet, humid weather. Many spots occur along the veins. They may enlarge and run together, causing the death of the entire leaf. Leaves partially killed appear as if sunscorched. This disease is distinguished from sunscorch by the presence of dark dots (spore-producing structures) barely visible on the underside of the leaf. The spore-producing structures develop while the leaves are still on the tree. Sunken reddish oval areas often develop on the infected twigs.