To know what control measures to take next year to prevent similar losses, it is important to recognize what is being observed. In some cases, growers will need to cut the fruit open to identify the problem. The following list briefly describes the most important fungus-caused diseases of apple fruits in Kentucky.
Apple scab Look for gray or brown corky spots, uneven or deformed fruit, and cracked skin and flesh.
Although apple fruit infections usually occur early in the season, pin point scab with rough, black, circular spots may develop in storage after harvest following late season infections. Bitter rot Usually, bitter rot infections produce slightly sunken, circular brown spots that may be surrounded by a red halo. When the spot becomes nearly an inch in diameter, spore-bearing structures appear in concentric circles on the diseased apple surface. The spore masses on the rotted fruit surface may take on a slight orange or pink color. A brown decay beneath the diseased spot extends towards the fruit core in the shape of a cone.