Fire blight is a highly contagious fruit tree disease caused by the Erwinia amylovora bacterium. Treatment and control is possible, even after trees become infected.
Erwinia amylovora infected crabapple trees.
Photo courtesy of Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
The leaves will still be attached but the branch will be black.
The tip of the shoot will typically curve downward in a hook shape. The bacterium which usually attacks in spring or early summer can be spread by splashing water, the gardener's hands or pruning tools.
Blight usually appears on a few limbs rather than the whole tree. You will know if your plants get it because the affected branches will suddenly turn black as if they have been singed. The burnt leaves will continue to cling to the scorched-looking stems.
The affected stem tips typically curve into a hook shape.
The disease moves down the shoot and forms a canker in the hardwood. Cankers will be sunken and dark in color. An amber gum may ooze from them.
Erwinia amylovora multiplies rapidly in this gum.
Apple and pear trees are most vulnerable but other types of fruit trees and roses can get it too. Ornamental trees like mountain ash, hawthorn and cotoneaster are also susceptible.
A fire blighted pear branch.
Photo courtesy of Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org
The best control is to plant resistant types of fruit trees.
Next best is proper fruit tree care:
Avoid feeding fruit trees too much nitrogen. Also, be careful not to apply too much water. Both these practices promote excessive vegetative growth and make the trees vulnerable to infection.
If, despite your best efforts, one of your edible fruit trees becomes infected; remove the blighted stems by cutting well back into healthy wood.
Dip the loppers into a bleach and water solution between cuts and again after you have finished pruning the blighted limbs. Otherwise, you may spread the disease to the next tree you prune.
Bag the blighted limbs and set them out with your yard waste.
Never compost diseased plant material.
Solutions for early and late blight.
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