Apple cork spot, bitter pit and Jonathan spot are physiological disorders that can affect apple quality and reduce visual appeal. Fruit growers sometimes confuse these disorders with damage resulting from insects or pathological diseases, particularly those involving fungus infections or hail injury. Cork spot, bitter pit and Jonathan spot are similar in that damage to tissue occurs mostly on the surface and in cell tissue just below the surface. Although apples affected with these disorders are edible, the unattractive external appearance often arouses consumer concern and reduces salability of fruit. Occurrence of cork spot and bitter pit appears to be related to reduced calcium availability in the developing fruit. Cork spot commonly occurs on York Imperial and occasionally on Delicious and Golden Delicious. Bitter pit can occur on many cultivars, but is most common on Granny Smith, Delicious, Grimes Golden and Northern Spy in Ohio. Low soil pH, light crops and excessively vigorous shoot growth are associated with increased incidence of these disorders. Jonathan spot, however, appears to result from toxins accumulating in the lenticels of the fruit skin. Although Jonathan is the most susceptible cultivar, Wealthy and Rome Beauty are also moderately susceptible to this disorder. Symptoms, time of occurrence and control measures available at this time are described below for each specific disorder.

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