Certainly, apple, crabapple and pear are common host plants of the bacterial incitant. But many members of the Rosaceae family of plants may be infected, and I think we often forget about these other landscape and nursery host plants. Some of these plants include cotoneaster, pyracantha, mountain ash, hawthorn and spirea .and many of these were infected in 2000. Primary symptoms on most of these plants are blackened blossoms, blackened stems, and blackened, sunken cankers. The name fire blight originated from the symptoms that appear as if the plants were scorched by fire.
Recommendations often suggest pruning infected twigs from plants when any infection is observed.
This may be a valid technique when infection levels are at reasonably low levels in the spring after infections manifest themselves. Hence, winter or dormant pruning is an advisable technique. When pruning strictly for fire blight, as opposed to general pruning of non-infected plants, it is probably wise to use a sanitizing agent between cuts and certainly between trees or shrubs. Because the bacterium may exhibit limited systemic activity, always prune at least 6-8 inches below any visible signs of infection. Antibiotics , primarily streptomycin derivatives, may be registered and available in your area.