Fire Blight: Symptoms, Prevention and Management for Fruit Trees

Fire blight is a bacterial disease caused by Erwinia amylovora. It can damage apples, pears, quince, crabapples and other susceptible plants in the rose family. There is no single cure for infected wood, so the best strategy combines correct identification, prevention and timely removal of infections.

How to recognize fire blight

• Blossom blight: flower clusters wilt, darken and may remain attached.
• Shoot blight: tender shoot tips wilt into a shepherd’s-crook shape; dark leaves often remain on the shoot.
• Cankers: discolored or sunken bark develops where the bacterium survives between seasons. Bacterial ooze may appear in warm, humid weather.

These signs are suggestive, not conclusive. Drought, freeze injury, root problems and other diseases can also cause dieback. Compare the pattern across the tree and ask a local Extension plant-diagnostic service when the diagnosis is uncertain.

When infection risk is highest

Blossoms are especially vulnerable when susceptible flowers are open, bacterial populations are active, and wetting occurs. Hail, wind injury or other wounds can also create entry points later in the season. A local fire-blight model can help estimate risk; see our fire blight prediction-model guide.

An integrated prevention plan

1. Start with site and variety selection. Choose cultivars and rootstocks suited to your region and consider documented fire-blight susceptibility. Resistance reduces risk but does not make a tree immune.
2. Avoid excess vigor. Apply nitrogen according to tree growth, soil or tissue information and local guidance. Excessively succulent shoots are vulnerable.
3. Protect bark and roots. Prevent mower, string-trimmer and cultivation wounds, and avoid chronic irrigation stress.
4. Inspect at bloom and during shoot growth. Mark suspicious areas and check again as symptoms develop.
5. Remove overwintering sources. During dormancy, prune confirmed cankers and dead infected wood when conditions are dry.

Pruning active infections

Pruning recommendations during the growing season vary with tree age, cultivar susceptibility, weather, infection severity and local disease pressure. Cutting a fixed distance below every visible symptom is not reliable because bacteria can extend beyond external discoloration. Follow current regional Extension guidance or work with a qualified arborist, especially when a scaffold, trunk or young tree is involved.

Keep removed material away from susceptible hosts and dispose of it as local rules allow. Tool-sanitation advice also varies by situation; follow your Extension program’s current protocol and avoid injuring healthy bark while working.

About sprays and biological controls

Preventive materials work only when the product label lists the crop and target disease and the application is timed correctly. Product availability, bacterial resistance, bloom safety and permitted uses differ by location. A prediction model signals risk; it does not authorize a pesticide application.

Before using any material, read the current label for timing, rate, protective equipment, re-entry and preharvest restrictions. Confirm recommendations with local Extension guidance. Do not substitute an insecticide, horticultural oil or general-purpose garden spray unless its label specifically supports the intended fire-blight use.

Where to go next

• Watch the fire blight identification and pruning video.
• Use the pear fire-blight symptom guide for pear-specific triage.
• Compare other pear foliage symptoms in our pear leaf-problem guide.
• Browse current bare root apple trees and pear trees, checking each product page for current characteristics.

Pesticide labels are the law. Use local Extension recommendations for diagnosis and region-specific management.