Bitter rot of Apples

Colletotrichum cingulata

Symptoms. Fruit infections can occur soon after bloom and appear as small, gray to brown flecks that may not enlarge until later in the summer. The most damaging fruit infections occur more than a month after petal fall. Small, sunken brown lesions, sometimes surrounded by a red halo, will form. The halo is especially visible on green or yellow fruit. When lesions are about 1 inch in diameter, the fungus forms small, black fruiting structures about the size of a pinhead around the infected area. In wet weather, masses of cream to salmon-pink colored spores are produced on the surface of the lesions. As the lesions enlarge, the rot progresses to the core of the fruit in a V-shaped pattern. This pattern differs from Bot rot that forms a cylindrical rot pattern extending to the core. Leaf spots, which are uncommon, start as small, red flecks that enlarge to irregular brown spots about 1⁄16 inch. Infected leaves usually drop prematurely.

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