Plant Doctor Archive

Mould on African Violet

I bought a small African violet at the garden centre — purple, double flowers, huge healthy green leaves. Now it is decidedly sick with a white covering over leaves and flowers. It looks as if it is covered in a fine film of flour. Maybe it's mould? What can I do to save it?

This is likely to be the fungal infection of powdery mildew, which appears on buds, flowers and leaves as a white powdery deposit. It usually appears when overcrowding occurs, i.e., when plants are placed close to one another (as can sometimes be so at garden centres), in wet conditions, or when it is hot, humid and still.

This can be prevented by ensuring there is adequate air movement around your plant at all times. If you have more than one African violet, space them well apart to allow for better circulation. The infection can spread rapidly and spores of the fungus are airborne.

When watering your plant, make sure you do not wet the leaves (as water can become trapped in the hairs) or at least allow sufficient time for it to dry out before dark. Foliage that stays moist is prone to fungal disease.

Do not allow your plant to become wet and cold, or hot and dry. Move it into a warm room in winter.

To treat, flowers and buds should be taken off the plant, and the foliage sprayed with a fungicide for powdery mildew. Repeat spray until symptoms have disappeared.

As a point of interest, African violets like to be slightly rootbound. Repot only when roots totally fill the container. Do this in between flowering, and place back in the same pot with fresh soil. Simply cut off weak or damaged roots. Keep the soil moist at all times.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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