Fire Blight
Fire blight is a highly destructive bacterial disease of rose-family pome trees.
Fire Blight at a glance
| Also known as | Erwinia amylovora |
|---|---|
| Affected parts | Blossoms, shoots, leaves, branches |
| Most at risk | Rose-family pomes: crabapple, hawthorn, quince, pyracantha, cotoneaster, pear |
| Main cause | Bacteria entering via blossoms/wounds in warm, wet weather |
| Severity | Very serious and fast — can kill branches or whole trees |
| Reversible? | No cure; control only by cutting well below the infection |
What to look for
- Leaves: Blossoms, leaves, and shoots suddenly turn brown to black as if scorched; blighted leaves wilt but stay attached rather than dropping.
- Whole tree: Rapid dieback spreading from blossoms/tips down into branches; in bad cases whole sections die within weeks.
Overview
Fire blight is a highly destructive bacterial disease of rose-family pome trees. It enters through blossoms and wounds in warm, wet spring weather and moves fast through the shoots and branches, killing tissue that looks scorched — as if burned. There is no cure: the only control is prompt, drastic pruning well ahead of the visible infection, with rigorous tool sterilisation.
Causes
The bacterium Erwinia amylovora spreading via rain, insects, and tools; entry through open blossoms and wounds; warm (24–30 °C) humid weather during bloom; and soft, lush (over-fed) growth.
Commonly confused with
Drought/frost dieback browns growth but lacks the shepherd's crook and bacterial ooze. Fungal canker is slower and more localised. The combination of scorched look, clinging blackened leaves, shepherd's-crook tips, and amber ooze is diagnostic of fire blight.
Which species are affected
Rose-family pomes only: crabapple, hawthorn, Chinese and Japanese flowering quince, pyracantha, cotoneaster, pear, mountain ash, and relatives. (Pomegranate, despite the name, is not a pome and isn't affected.)
Treatment
There is no cure. Prune out infected wood 20–30 cm (8–12 in) below the visible damage, ideally in dry/dormant conditions, sterilising the tool between every single cut (10% bleach). Bin or burn prunings — never compost. Avoid heavy nitrogen and don't prune in wet weather. Copper or (where permitted) streptomycin sprays at bloom give some protection in high-risk seasons.
Prevention
Choose resistant cultivars; avoid lush over-fed growth; sterilise tools between cuts; remove infected wood promptly; protect blossoms in warm wet springs; keep susceptible species apart.