Bacterial Canker on Peach and Apple Trees: Identification and Management

Key Diagnostic Clue

Sap oozing from split, peeling bark with a fermented, alcohol-like smell strongly indicates bacterial canker (often Pseudomonas syringae or Erwinia amylovora). This infection enters through wounds—commonly from lawn equipment, winter injury, or pruning cuts.

Assessment Steps

1. Smell the sap: Alcohol odor = bacterial infection.
2. Probe with a knife: Determine depth. Superficial infections may be scraped out.
3. Check for mechanical damage: Look for mower/string trimmer scars at the base.

Treatment Options

• Superficial infections: Scrape away loose bark and diseased tissue to healthy wood. Apply a streptomycin-based product (e.g., Fire Blight Spray by Fertilome) per label.
• Deep infections: No cure exists. The tree may linger for years or die suddenly in summer heat.
• Prevention: Mulch wide rings around trees to eliminate equipment damage. Prune only in dry weather; sanitize tools between cuts.

Realistic Expectations

Infected trees often survive for years but remain reservoirs for bacteria. Monitor closely; remove if structural failure risk increases or if nearby healthy trees show symptoms.

Contact your local extension office for region-specific streptomycin regulations and timing.