Fire Blight is a bacterial plant disease that affects plants in the Rosaceae family, including trees and shrubs in orchards, nurseries and home landscape plantings. The plants affected include Amelanchier (serviceberry), Chaenomeles (flowering quince), Cotoneaster (cotoneaster), Crataegus (hawthorn), Eriobotrya (loquat), Malus (apple and crabapple), Photinia (photinia), Prunus (flowering almond, plum and cherry), Pyracantha (pyracantha), Pyrus (pear), Rosa (rose), and Spirea (spirea). Both fruit bearing and ornamental trees and shrubs in these families are susceptible to the disease. This means ornamental pear, crabapple and plum trees are susceptible as well as fruit bearing apple, pear and plum trees.

Fire Blight is caused by a bacteria (Erwinia amylovora) which attacks starting generally from the blossoms or flowers and moving up to the twigs and then the branches. Fire blight gets its name from the burnt appearance of affected blossoms and twigs. Flowers turn brown and wilt; twigs shrivel and blacken, the ends often curling. In more advanced cases of bacterial infestation, cankers, discolored oozing patches, form on branches. The translucent amber or reddish ooze contains masses of bacteria. Heavy persistent infections can be fatal. The bac­teria can over-winter in are spread from the cankers. Insects, wind-blown rain and careless pruning practices can also spread the disease.

       Early spring, when susceptible plants start to bloom, is the time to start spraying with Fertilome Fire Blight Spray to prevent the disease. The first spray application should be when the blossom are swelling and then re-spray the plant every 4 days during bloom time. Apply additional sprays after bloom time at intervals of 5 to 7 day while weather conditions are favorable. Favorable conditions include high soil moisture, rapid bud and shoot development, temperatures persisting at 60° to 75° F., and/or prolonged rain or high humidity.

 

More about Fire Blight from University of Missouri Extension