Fire blight is probably one of the most destructive diseases of fruit trees in Alberta. It is caused by a bacterium that enters fruit bearing trees through blossoms or tree wounds. The bacterium forms cankers that dispense the bacteria in the form of amber/brown secretions. These secretions are spread throughout a tree by rain, humidity, by birds and by insects. The disease develops best in warm, humid temperatures. You may see it occur erratically throughout a tree and it is unpredictable. Occurrences that become serious or infect the main limbs in a mature tree can result in serious structural damage and even death.
Wilted blossoms, or blossoms that turn brown in the spring.
Fruits that are young may appear to be covered in oil, and may ooze milky, tawny or clear fluid (it may also smell bad.)
Limbs begin to die (usually tips first) and appear to be charred by fire.
In the winter months you will notice the dead leaves and shrivelled berries cling to the branches.
Fruits may turn russet and leathery
Remove root suckers from the base of your tree.
Control insect movement.
There is no chemical treatment for blight; proper pruning and removal of infected branches is the only effective method.
Prune during the dormant season: winter/spring/fall
Diseased branches should be cut 25cm-45cm below the diseased area because blight may spread past the visible areas.
Regularly inspect your tree for new infections and remove the infected limbs.
Avoid excessive pruning.
If more than 50% of the tree is infected consider removal due to structural issues, risk that the disease can spread to other trees, as well as tree health and longevity.