Affects rosaceous plants, primarily members of the Pomoideae . Economically important hosts are apple and pear. The commercial implications of fireblight outbreaks are aggravated by the limited effectiveness of current control measures.
Necrosis gives tissue a scorched, blackened appearance, giving rise to the name fireblight.
Symptoms are often localized to blossom bracts or young shoots but, in highly susceptible hosts, can spread systemically resulting in death of the entire tree. Infections can vary in severity depending on climatic conditions and host susceptibility. Browning and wilting can be seen in the shoot and upper leaves of the infected plant.