Plant Doctor Archive

White mould on Astelias

I have two astelias that seem to be rotting away at the base, growing a furry white mould at the base of each leaf. They are not keeping their normal silver colour and basically seem to be giving up their will to live. They're planted in a well-drained area, get the afternoon sun and water when I can remember to do so.

Astelias prefer a cool, moist, peaty, free-draining soil. Semi-shade is ideal — avoid the hot midday sun.

When planting, take care not to bury the crown as this will cause the rotting you describe. Alternatively, soil or rotting leaves falling amongst your astelias' leaves will have the same effect.

Astelias require regular watering, especially during dry periods. Mulch plants to help conserve soil moisture.

It is possible your astelias are suffering from phytophthora which is a root rot and can be caused by irregular watering. Unfortunately, there is little that can be done if root rot is the problem. A spray called Ridomil is effective. Mancozeb is a good protectant spray but will have no effect once the disease is present.

Remove infected plant material and burn or dispose of in the rubbish bin to prevent the disease spreading. Do not replant astelias into the same position.

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

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