Brooks fruit spot is a minor disease that occurs throughout the northeastern and mid-Atlantic apple growing regions in the United States. The disease is caused by the fungus Mycosphaerella pomi, Brooks fruit spot is also known as Phoma fruit spot. The disease attacks apple and crabapple trees.

Symptoms

Brooks spot appears on immature fruit in late June and July. Spots on fruit are about 1/4 inch in diameter, irregular in shape, dark green, slightly sunken, and usually most numerous on the calyx end. On red-skinned cultivars, lesions are dark red to purple. On light-skinned cultivars lesions remain dark green. If infection occurs early, fruit may crack. Lesions may be confused with those of bitter pit or cork spot, however, unlike those of cork spot or bitter pit, lesions of Brooks spot are shallow and the flesh of the fruit is not corky beneath. Unless infected fruit is placed in cold storage immediately after harvest, the spots increase in size and become more sunken, thus more visible. Occasionally, lesions appear on leaves as small, purple spots.

Disease Cycle

The fungus overwinters in apple leaves on the orchard floor. About the time of petal fall, ascospores are discharged from fallen leaves. Rain and high humidity favor spore discharge and infection of fruit. Infections continue until midsummer, although they decrease as the season progresses.

Disease Management

Sanitation practices such as removing fallen leaves from the orchard floor will help in the control of Brooks fruit spot. Routine fungicide applications normally control this disease in Pennsylvania. Summer fungicide applications should not be extended beyond 14-day intervals. Jonathan, Stayman, Rome Beauty and Golden Delicious are susceptible. Delicious is somewhat resistant.