Olive, velvety spots, 1/4 inch or more in diameter, appear on the leaves. The tissue around the spots may be puckered. The leaves often turn yellow and drop. In a wet year, the tree may lose all of its leaves by midsummer. The fruit and twigs develop circular, rough-surfaced, olive green spots that eventually turn corky and black. The fruit is usually deformed.
Rake up and destroy infected leaves and fruit in the fall. When planting new trees, use resistant varieties. Apply a fungicide labeled for apple scab, following label directions.