Usually only one spot occurs per fruit. With time, the spots enlarge and commonly develop a series of brown and black concentric bands or rings. The rotted fruit finally turns black. The decayed tissue remains firm to leathery, and holds its original shape until the entire fruit is rotted. In cold storage, the flesh of black rot-infected fruits remains firm, in contrast to several other apple rots.
Leaves Starting at petal-fall or somewhat later, small, purple specks appear on infected leaves.
Black pycnidia, like those that appear on rotted fruit, may develop on the upper surface in the centers of the older leaf spots. These pycnidia help to distinguish frogeye leaf spots from similar spots caused by spray injury. Twigs, Limbs, and Trunks Small, slightly sunken, reddish-brown areas develop in the bark. These areas slowly enlarge and darken to form cankers. Cankers may continue to expand a little each year, and may extend down the limb for 3 feet or more.