The disease is more of a problem in European countries than in North America and is especially of major concern in Japan. Sometimes called black spot, pear scab resembles apple scab, Venturia inaequalis, in nearly all respects, and is caused by the closely related fungus Venturia pirina. Leaf infection of pear is not as common as apple scab on apple leaves. Some pear cultivars are more susceptible to scab, but cultivars resistant to pear scab in one region of the country may not be resistant in another region. Symptoms Pear scab occurs on leaves, shoots and fruits.
Symptoms are very similar to apple scab.
A major difference, however, is the frequent appearance of pear scab on twigs, where it can overwinter and sporulate to initiate new infections in the spring. Lesions on leaves and petioles begin as round, brownish spots that eventually become velvety in appearance. Conidia, spores of the fungus, are produced within these lesions. Later in the season, small spots can be observed on the lower surface of the leaves. These are usually the result of late spring or early summer infections.