Fire Blight

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.

Symptoms:

• 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

Prevention:

• 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.