Fire blight

Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard in a single growing season. The causal pathogen is Erwinia amylovora, a Gram-negative bacterium in the genus Erwinia, order Enterobacterales. It is a short rod with rounded ends and many peritrichous flagellae. Pears are the most susceptible, but apples, loquat, crabapples, quinces, hawthorn, cotoneaster, Pyracantha, raspberry and some other rosaceous plants are also vulnerable. The disease is believed to be indigenous to North America, from where it spread to most of the rest of the world. Fire blight is not believed to be present in Australia though it might possibly exist there. It has been a major reason for a long-standing embargo on the importation of New Zealand apples to Australia. Japan was likewise believed to be without the disease, but it was discovered in pears grown in northern Japan. Japanese authorities are, however, still denying its existence, and the Japanese scientist who discovered it is believed to have committed suicide after his name was leaked to affected farmers. In Europe it is listed as a quarantine disease, and has been spreading along Hawthorn (Crataegus) hedges planted alongside railways, motorways and main roads. Experiments in the early 1800s demonstrated that E. amylovora caused disease in plants, the first time that this could be shown. It is generally accepted that this destructive crop bacterium initially originated in North America. Today, E. amylovora can currently be found in all the provinces of Canada, as well as in some parts of the United States of America, including Alabama, California, Colorado, Connecticut, Georgia, Illinois, Maine, Maryland, Massachusetts, Michigan, New York, North Carolina, Ohio, Oregon, Pennsylvania, Texas, Utah, Virginia, Washington, West Virginia and Wisconsin.