It can be identified by the dead twigs it creates throughout a tree. These diseased twigs are normally scattered throughout the tree, but the disease commonly attacks the last six to 12 inches of a branch. The leaves wilt at the tips of these limbs and turn black within a couple of days. The tissue under the bark of the most recently killed leaves will be darkened and moist in appearance.
Once a tree has been infected, the diseased portions should be cut out and burned. The cuts should be made six to eight inches below any dead tissue to be sure all affected wood is removed. After each cut, pruning tools should be disinfected by dipping them in a solution of a half-cup of household bleach and five cups of water. Disinfecting the pruning tools between cuts will help to reduce the chances of spreading the disease. When you have finished removing all the affected twigs, rinse the clippers in running water and oil them to prevent rusting.
Fruit trees can be protected from fire blight by a spray program beginning before and continuing through the blooming stage. But, sprays will not control the disease in infected branches that are showing the symptoms. If you are unable to prune the infected branches from your tree due to its size or some other condition, the next best option is to make plans to thoroughly clean up around the tree this fall and follow a good spray program for fire blight next winter/spring.
Fruit trees are not the only ones susceptible to this disease; it can also attack Bradford pears, hawthorns, pyracanthas and flowering crabapples. For more details about this problem in our home orchards, call the Walker County Extension Office at 638-2548.
Norman Edwards is coordinator of Walker County Extension Service.