Fire blight is a disease which is commonly found in ornamental pear, crabapple, hawthorne and mountain ash trees in Bucks and Montgomery County, especially following a wet spring. New infections usually begin in the flowers each spring. The bacteria is spread to wounds or natural openings by wind, water, insects or pruning tools. Infected blossoms look like they have been soaked in water, wilt, and then turn dark brown. As the bacteria progresses, leaves wilt, turn brown and remain on the tree. This creates a fire-scorched look, hence the name "fire blight." The branch tips on infected twigs may bend over to create a "shepherd’s crook." Fire blight can also cause dark, sunken cankers that have a narrow callus ridge along the outside. In some cases a creamy bacterial ooze may appear on cankers or fruit. This fruit may dry and remain on the tree.
There is no single management practice that completely controls fire blight. A combination of cultural practices to reduce tree susceptibility and disease spread, and chemical control to protect against infection can reduce the disease. Treat trees that expressed visible symptoms in previous growing seasons or high value trees growing adjacent to symptomatic trees. If not managed, fire blight can destroy the blossoms, fruit, and stems of the plant, and even kill the plant. Properly timed trunk injections of antibiotics can provide seasonal suppression of this disease. Growth regulator, used in conjunction with the antibiotics, can also be used to minimize shoot growth, which will minimize the shoot blight stage of a fire blight infection.
Contact Plant Health Solutions for proper diagnosis and to develop a treatment plan.