Managing Gummosis in Young Plum Trees: Causes and Solutions

Managing Gummosis in Young Plum Trees: Causes and Solutions

A 7-ft plum tree (3 years in ground) oozes amber sap from trunk (6–18 inches up). Started at a spring pruning cut. Bark has cracks attributed to rapid growth. Owner used systemic insecticide (for citrus psyllid) on all orchard trees.

Causes of Gummosis

• Rapid growth: Fast trunk expansion splits thin bark, especially after fall fertilization.
• Pruning wounds: Spring cuts may bleed sap.
• Systemic insecticides: Can stress trees; also contaminate fruit.
• Bacterial canker / borers: Less likely if no holes or sawdust.

Recommendations

1. Stop fall fertilization. Fertilize only in late winter/early spring per schedule.
2. Switch to neem oil for psyllid control—organic, no fruit residues, bee-safe if not sprayed during bloom.
3. Assess trunk cracks: If bark is loose all around, tree may girdle and die. Consider removal.
4. If cracks are partial: Prune dead wood, avoid further stress, monitor.

Systemic Insecticide Caution

Systemics move into all plant parts—including fruit. Apply only post-bloom, stop well before harvest. Neem is a safer alternative for home orchards.

Rapid growth + fall fertilizer = split bark. Slow down, and the tree may heal.