Symptoms
- check_circleAmber, brown, or clear gummy ooze from bark or stems
- check_circleSunken, discoloured patches (cankers) beneath the gumming
- check_circleGum exuding from pruning wounds or cracks
- check_circleDieback above the gumming point in severe cases
Causes
- arrow_rightFungal pathogens such as Phytophthora or Cytospora entering through wounds
- arrow_rightBacterial canker infections
- arrow_rightBorer pests tunnelling under bark
- arrow_rightPhysical damage from pruning, frost, or sunscald
- arrow_rightWaterlogged soil causing root and crown rot
How to Diagnose
Scrape back the bark near the gum — brown or orange staining beneath confirms fungal involvement. Check for borer frass (sawdust-like material) if gum is around holes.
Treatment
Cut out cankered tissue to clean wood and sterilise tools. Apply a copper-based fungicide. Improve drainage around the base. Treat for borers if present. Avoid injuring bark during cultivation.
Prevention
Avoid wounding bark unnecessarily. Apply tree wound paint to large pruning cuts. Maintain good drainage. Plant in well-draining soil and avoid overwatering.
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