Fire blight is an especially destructive bacterial disease on plants such as apple, crabapple, pear and quince. Contributing factors include cool, wet weather; infected nursery stock; overhead sprinkler irrigation. In late spring, symptoms may be observed on blossoms, fruit, twigs, leaves, limbs, and the trunk. The pathogen generally enters the tree through wounds, natural openings in the leaves, or through flower parts. Bacteria in infected tissues lie dormant in late summer and remains so until the following spring.
In late spring, symptoms may be observed on blossoms, fruit, twigs, leaves, limbs, and the trunk. The infection may progress down a shoot or small branch and start a stem canker in a larger branch or stem. The inner bark of these cankered areas appear water-soaked, turning green to brown. The surface withers and wrinkles. The infested bark often attracts more insect activity than normal. Dead leaves remain attached to dead branches.
Several steps must be taken to manage and prevent this disease. It’s crucial that affected areas are removed. Prune dead or dying twigs and branches in the fall, using disinfected tools. Do the same in the spring, should an outbreak occur. Be sure not to over fertilize the tree, since that may accelerate bacterial growth. We recommend a fungicide injection at the first sign of outbreak, but preferably before for attempts at prevention on an annual basis. After the injection, the infected limbs and foliage already affected will not be repairable and will still require pruning. We also highly recommend a micro-injected antibiotic be done as well, which acts as a systemic aid in the suppression of this disease.