Erwinia amylovora is a member of the family Enterobacteriacae, are gram-negative, rod-shaped and flagellated on all side. Is a native pathogen of wild, rosaceous hosts in eastern North America. It was the first bacterium proven to be a pathogen of plants and was shown to be the causative agent of the necrotic disease fireblight, an important disease of apples and pears in many parts of the world. Symptoms of fire blight can be observed on all above ground tissues including blossoms, fruits, shoots, branches and limbs, and in the rootstock near the graft union on the lower trunk. During severe disease outbreaks, the rapid spread of bacteria through host tissue can lead to the loss of entire trees in a single growing season. Fireblight is therefore a highly destructive disease and is of major economic concern to fruit growers world-wide. Early detection is therefore crucial for its control.