Fire Blight 🦠
At a glance
- Cause: Bacterial disease of apples, pears, and related rose-family plants
- Tell-tale sign: Blackened wilted shoots that look scorched, often with a shepherd’s-crook bend
- Severity: Serious on susceptible fruit and ornamental trees
How to identify
Fire blight makes blossoms, shoot tips, and twigs suddenly wilt, blacken, and look scorched. Young shoots may bend into a shepherd’s crook. Cankers can ooze amber bacterial droplets in warm wet weather.
What causes it
The bacterium spreads by rain, irrigation splash, insects, pollinators, and pruning tools. Bloom-time infections are common when warm wet weather lines up with susceptible flowers.
Treatment & management
Following Integrated Pest Management:
- Prune infected shoots well below visible damage during dry weather.
- Disinfect tools between cuts when working active infections.
- Avoid overhead irrigation and excess nitrogen, especially during bloom.
- Remove severe cankers when possible.
- Choose resistant cultivars for future plantings in fire-blight-prone sites.
Prevention
Do not irrigate during bloom on susceptible trees. Avoid heavy nitrogen flushes and prune for airflow.
Affects (in this guide)
Apples, pears, crabapples, pyracantha, quince, and some other Rosaceae; relevant to Toyon and rose-family landscape plants as a lookalike concern