Fire blight is a serious bacterial disease of apples, pears, quinces, and several plants in the rose family (Rosaceae), including hawthorn, cotoneaster, firethom (pyracantha), mountain ash, blackberry, and raspberry. Outbreaks of this disease are usually most severe in areas with a warm, humid climate, especially when these conditions occur during the bloom period of the tree or plant involved. This publication is aimed especially at growers of apples and pears, as many varieties and rootstocks of these fruit are very susceptible to the disease. This bulletin serves as a practical guide for the recognition of conditions conducive to disease development, identification of symptoms, prevention of disease development, and control of fire blight, including disease prediction. Key references are included for additional information on different aspects of fire blight.