Fire blight is a destructive bacterial disease of apples and pears that kills blossoms, shoots, limbs, and, sometimes, entire trees. The disease is generally common throughout the United States wherever apples are grown, although outbreaks are typically very erratic, causing severe losses in some orchards in some years and little or no significant damage in others. This erratic occurrence is attributed to differences in the availability of overwintering inoculum, the specific requirements governing infection, variations in specific local weather conditions, and the stage of development of the cultivars available. The destructive potential and sporadic nature of fire blight, along with the fact that epidemics often develop in several different phases, make this disease difficult and costly to control.
Of the apple varieties planted in the eastern region, those that are most susceptible include:
- Tydeman’s Red,
- Pink Lady.
Cultivars that are moderately resistant include:
- Golden Delicious.
All strains of Delicious are highly resistant to fire blight, except when tissues are damaged by frost, hail, or high winds.
Read this article on Fire Blight for more information.
Answer provided by Alan R. Biggs, West Virginia University.