Black Rot / Soft Rot

About this condition

A disease caused by bacterial or fungal infection that causes rapid blackening and soft rot of stems and leaves. It progresses quickly, making early response critical.

Common symptoms

• Part of a stem or leaf suddenly turns black and becomes soft
• Affected tissue becomes water-soaked and collapses easily when touched
• Rot can spread rapidly upward or downward through the stem
• An unpleasant odor may be present at the affected site

Common causes

• Bacterial or fungal pathogens invading and multiplying during hot, humid conditions
• Infection entering through wounds such as cuts or insect feeding damage
• Onset in plants stressed by overwatering or poor air circulation
• Transmission from contaminated soil or unsterilized tools

Prevention (growing conditions & routine care)

Maintain good air circulation and avoid overwatering during hot, humid periods. Use clean tools and fresh soil when repotting or taking cuttings. Allow cut surfaces to dry and callous before planting.

Related guide

When to see a vet

What can a nursery or grower do?

Specialist nurseries and growers can assess the extent and progression of infection, help identify salvageable parts, and advise on specific environmental improvements such as ventilation, soil, and watering practices. Guidance on handling cut surfaces is also available.

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