Hawthorn: Fire blight

Biology

Fire blight is a bacterial infection of shoots which enters the plant through blossoms, vigorously growing shoot tips, young leaves, and wounds. Blossom clusters appear blighted. Shoots suddenly wilt, turn black and die back, presenting a “scorched” appearance. Purplish cankers may develop on the shoots. During wet or warm weather, the cankers may ooze brown sticky droplets. Newly infected wood is reddish, while older infections are black. The bacteria are easily spread by rain and pollinating insects. Fire blight also affects pear, pyracantha, apple, and related species. It is not a proven problem in western Washington.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Plant resistant species. For example, Crataegus phaenopyrum (Washington thorn) is reported to be resistant to fire blight.
• Immediately prune out and destroy infected tissues. Make pruning cuts at least 6″ below infected tissues and sterilize tools between cuts. Do not do regular pruning at the same time as blight removal.
• Avoid wounding plants.
• Use moderate amounts of nitrogen fertilizer to minimize susceptible shoot growth.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• None recommended