Pollinating insects visiting contaminated flowers spread the disease to non-infected flowers. Infected blooms first appear water soaked and later begin to wilt, shrivel and turn brown or black (Figure 4-154). Blossom blightīlossom blight is observed in the spring when flowers are infected. Severely infected trees with fire blight appear to be "scorched" by fire Symptomsįire blight attacks many different parts of the tree, and fire blight symptoms are often referred to the part of the tree attacked - blossom, shoot, fruit, limb and trunk, and collar or rootstock blight. Fire blight has become a serious problem in high density apple plantings that contain new susceptible varieties and dwarfing rootstocks (Figure 4-153).įigure 4-153. The pathogen has caused most damage in southwestern Ontario, where, in some years, whole orchard blocks have been destroyed due to severe infections. amylovora is found in most areas of the province where apples are grown.
Raspberry can be infected by fire blight bacteria, but the raspberry strain cannot infect apple, pear or ornamental plants. The host plants include quince, crab apple, hawthorn, cotoneaster, mountain ash and firethorn. The disease is caused by a bacterium, Erwinia amylovora (Burrill), which infects hosts in the Rosaeceae family. Fire blight is a serious disease causing considerable damage and economic losses in apple and pear.
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