Fire Blight
Erwinia amylovora
Overview
A highly destructive bacterial disease of apples, pears, and related rosaceous plants. Infected shoots appear scorched by fire, with characteristic shepherd's crook bending of shoot tips.
Symptoms
Blossoms turn brown and water-soaked, then wilt. Shoot tips bend into a characteristic shepherd's crook shape. Leaves turn brown to black but remain attached. Bark develops sunken, dark cankers that may ooze bacterial slime. Rapid spread in warm, wet weather.
Environmental Conditions
Humid
Prevention
Plant resistant varieties. Avoid excessive nitrogen fertilization. Prune to improve air circulation. Apply streptomycin or copper sprays during bloom. Avoid overhead irrigation during bloom.
Management
Prune infected branches at least 12 inches below visible symptoms during dry weather. Sterilize pruning tools between cuts. Apply copper sprays. Remove severely infected trees. Biological controls (Serenade) during bloom.