Fire blight, caused by the bacterium Erwinia amylovora, is one of the most destructive diseases in apple and pear production. Fire blight can infect other members of the rose family including quince, juneberry, hawthorne, mountain-ash, and Pyracantha. With the exception of China and Australia, fire blight occurs worldwide in all regions where apples and pears are grown. Under conditions favoring disease, fire blight can infect, blight, and kill trees across large acreages over the course of only a few weeks. Disease outbreaks are often sporadic and the disease is difficult to manage. Estimated economic losses in the U.S. exceed $100 million annually.