Tree and Shrub Disease

Fire Blight is a common disease which can infect fruiting trees such as pear, apple, crabapple, hawthorne, and other related trees. Visually, clusters of flowers may begin to wilt and turn brown shortly after blooming followed by twig blight. Twig blight will show symptoms of leaves wilting, turning brown and remaining in place on a stem or branch (which may distort like a hook) of the tree. The name 'fire' blight comes from the appearance of scorched leaves. Fruit will also take on this 'scorched' look when infected.

The warmth of spring accompanied by high amounts of moisture favor the development and spread of this disease. As spring hits, the infected cankers will ooze a sticky, sweet sap which contains the bacteria that causes fire blight. The sap may drip onto new, uninfected branches or be carried by water droplets, insects or mechanical means to uninfected parts of the tree or to new areas containing healthy trees thus spreading the disease. As the infection spreads through the tree, new cankers are formed which contain the disease. In winter, fire blight remains inactive near cankers on the infected tree and the cycle resumes once spring returns.

Proper pruning of infected branches and twigs may help to keep the spread of the disease to a minimal; however, it is important to note that the canker harbors the disease in winter and this is the ideal time to remove and destroy infected parts of the tree.

Disease Development Favored by: Humid, warm weather Spreads easily through wounds on the tree Corrective Measures: Prune in late winter 8 inches under diseased areas of tree (if the pruning can wait till then) Clean all tools after use as to keep from spreading the disease to new branches or trees Destroy all branches and twigs after removing them from the tree Multiple applications of fungicides in early spring may reduce the spread and severity of this disease (spray once a week after the first blooms occur until all blooms have blossomed) Use low-nitrogen deep root fertilization to keep from rapid growth though aid the health of the tree to recover from stress of the disease Use resistant trees in place of susceptible trees

Fire Blight: note the hook-shaped twig

Infected leaves