Fabraea leaf spot
Diplocarpon mespili (Soraur) Sutton
Lesions on leaves and petioles start as small, circular purple to black pinpoint spots (A, B). They enlarge quickly to a diameter of about 10 mm, develop a dark brown to black interior, and may coalesce to form larger areas of infection. On fruit, lesions have a similar appearance to those on leaves but tend to be larger and cause the fruit to crack (C). Heavily infected leaves and fruit drop prematurely.
Common to all fruit-growing regions in eastern North America; most problematic in warm and humid production regions.
Mycosphaerella leaf spot is similar, but the interior tissue of lesions caused by Mycosphaerella is much lighter than those caused by Diplocarpon.
Removal or destruction of leaf litter can reduce early season disease pressure. Regular applications of fungicides from white bud through late summer may be necessary to prevent disease in orchards that were severely diseased in previous years. Primary infections usually occur during the 6 weeks after petal fall. Bosc and Seckel pears are more susceptible than Bartlett.
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