Sooty Mold

About this condition

A secondary fungal condition in which mold grows on the honeydew excreted by pests such as scale insects or aphids, coating leaf and stem surfaces with a black sooty film.

Common symptoms

• A black sooty powder or film coats the surface of leaves and stems
• The sooty coating can sometimes be wiped off with a finger or cloth
• Leaf color deteriorates as photosynthesis is impaired
• Closer inspection may reveal scale insects or aphids on the plant

Common causes

• Honeydew excreted by pests such as scale insects or aphids coats leaf surfaces
• Poor ventilation prevents honeydew from evaporating, allowing mold to establish
• Pests migrating from nearby plants have established on the plant
• Delayed pest management has allowed significant honeydew accumulation

Prevention (growing conditions & routine care)

Inspect plants regularly for early detection of scale insects and aphids. Maintain good air circulation and quarantine newly purchased plants to prevent introducing pests.

Related guide

When to see a vet

What can a nursery or grower do?

Specialist nurseries can identify the causative pest, advise on physical removal methods, and recommend environmental improvements such as better air circulation. Guidance on removing sooty mold and setting up conditions less prone to recurrence is also available.

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Other problems with this plant

The same problem in other plants