Mildew menace

QWhat is the powdery substance that’s appeared on several leaves of different plants?

Terry Hodges, via email

AThis is powdery mildew, a common fungal problem. You can help plants recover by applying a systemic fungicide such as FungusClear Ultra now, followed in April by a dressing of a granular fertiliser from April to September, forking it around the roots.

Feed plants with sulphate of potash to boost their resistance, from April to September, watering it in afterwards.

Store begonias in trays of old compost Begonia tubers should be lifted and stored somewhere frost-free over winter

Powdery mildew can be treated with a fungicide