Fire Blight on Fruit (5511)

Fire blight is destructive to apples and quince and is the most serious pear disease in the eastern United States. Caused by the bacterium Erwinia amylovora, the disease can attack some 75 species of plants of the rose family. Fire blight also occurs frequently on pyracantha, spirea, hawthorn, and mountain ash. In fruit trees, the disease can kill blossoms, fruit, shoots, limbs, and tree trunks. Certain varieties of apples are more susceptible than others. Susceptible varieties include Jonathan, Rome, Yellow Transparent, and Idared.

Symptoms
The disease gains entry to the tree through two main points, blossoms and new shoots, and often appears first in spring as blossom, fruit spur, and new shoot blight. Infected blossoms wilt rapidly and turn light to dark brown. Bacteria may move through the pedicel to the fruit spur and out into the leaves. Here they follow the midrib and main veins, which soon darken. The leaves wilt, turning brown on apples and quince and dark brown to black on pear. The blighted leaves remain attached for much, if not all, of the growing season. Some remain even after normal leaf fall.

For more information, please see this Penn State Tree Fruit Production Guide Web page.

Penn State Horticultue Department

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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