Fire Blight (bacterium - Erwinia amylovora): This bacterium causes twig dieback and is common on apples and pears as well as some 75 other plant species. Blossom blight is common on apples. Infected blossoms wilt and turn black rapidly. The foliage does not immediately abscise due to the rapid rate of death. Twig blight is common and can result in dieback ranging up to 12 to 36 inches of twig length. The bacteria overwinters in cankers. Bacteria oozes from the cankers in early spring and are carried by wind and insects to healthy foliage. Resistant varieties should be used when available. Fungicides containing copper will cause russetting on apples. Trees which have had fire blight should be pruned to remove overwintering cankers. Nitrogen levels should be kept low. No organic nitrogen sources should be used as they encourage continual growth which is susceptible to the bacterium. Make cuts from 4 to 6 inches below the visible cankers. All pruning equipment should be sterilized with a one part household bleach to nine parts water solution. For more information, refer to the pear section. See also Fire Blight of Apple and Pear (NCSU).

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