This disease should not be confused with the fire blight or leaf spot diseases of pears. Leaf blight and fruit spot are caused by the fungus Fabraea maculata , which infects the leaves, fruit, and shoots of pear and quince and the leaves of apple trees. The disease can build up rapidly, even in orchards where it has not been a problem. If conditions favor the disease and it is not controlled, pear trees may become defoliated in a few weeks. Susceptible pear varieties often are defoliated by mid-summer, resulting in dwarfing of fruit and reduction of fruit buds.
Infected fruit is unmarketable since fruit are usually cracked, and misshapen.
In the nursery, early defoliation and twig infection result in stunted growth of the tree. Symptoms Leaf spot can be found on petioles, leaves, shoots and fruits. Leaf spots first appear as small purple dots on the leaves nearest the ground. They grow to circular spots becoming purplish black or brown. A small black pimple appears in the center of the spot.