Apple Disease - Brooks Fruit Spot

Brooks fruit spot attacks apple and crabapple trees and is rarely found in well-sprayed orchards. When cover sprays are stopped too soon, or when trees are not well-pruned and sprayed, severe losses can occur. Varieties such as Jonagold, Golden Delicious, Fuji, Mutsu (Crispin), Gala Rome Beauty, Stayman, Jonathan, and Grimes Golden are quite susceptible.

Symptoms

Spots on fruit are about ¼ inch in diameter. They are somewhat irregular in shape, slightly sunken, and usually most numerous on the calyx end. On red fruit surfaces spots are red to black; on green and yellow fruit surfaces they are dark green.

Spots may be quite inconspicuous at harvest. Unless infected fruit is placed in cold storage immediately after harvest, the spots increase in size and become more sunken, thus more visible.

Disease cycle

The disease cycle is much like that of apple scab, except it begins later in the spring. About the time of petal fall, ascospores are discharged from fallen leaves. Rain and high humidity favor spore discharge and infection of fruit. Ascospores penetrate the fruit through the lenticels and the leaves through the stomata. Fruit are most susceptible 10-30 days after petal fall. Fruit lesions appear mid- to late summer. Leaf infections remain quiescent until late summer, when small purple spots begin to appear.  

Disease management

Routine fungicide applications normally control this disease in Pennsylvania. Summer fungicide applications should not be extended beyond 14-day intervals.