Symptoms: Named for the scorched appearance of infected leaves, fire blight is a destructive bacterial disease (Erwinia amylovora) found on apples, pears and other members of the rose family. The disease enters the tree at the tips of the branches and then travels down the stems, causing dieback. It attacks soft new growth first, so you would notice dieback at the top of the plant.
Most infected leaves and branch tips wilt rapidly turn brown or black; the leaves die but do not drop off. Trees will also develop reddish water soaked lesions on the bark. On warm days, these lesions ooze an orange-brown liquid. Fire blight kills blossoms, shoots, limbs and sometimes, entire trees.
The fire blight bacteria overwinters in infected bark and is spread by splashing rain, dew, wind and insects. It spreads rapidly in moist, warm weather, especially during bloom.
Control: Select resistant varieties whenever possible. Avoid heavy pruning or excess applications of nitrogen fertilizer, both of which encourage new growth. Avoid planting close to wild plants of hawthorn, apple or pear. As soon as fire blight is discovered, prune off infected branches 1 foot below the diseased sections and burn them to prevent further infection. Dip pruning shears into a 10% alcohol or bleach solution between each cut to avoid transmitting the disease from one branch to another.
Fire blight spread can be reduced by applications of products that contain streptomycin sulfate as the active ingredient. These products are available under various trade names and may be purchased at select garden supply stores. To obtain best disease control with these sprays, the first applications should be made at the start of the bloom period and every five to seven days thereafter.
Photo Credit: Texas A&M AgriLife Extension Service