Grey mould (Botrytis) is a fungal disease that thrives in cool, damp conditions, and appears on leaves, stems and fruit as a fluffy grey growth, sometimes with black spots in it. It attacks a wide range of plants, particularly in damp and poorly ventilated conditions, both indoors and out.

Control

Cleaning away dead or dying leaves, flowers, stems and fruits will limit the spread of Botrytis, as these often act as initial hosts. Poorly ventilated conditions, such as inside badly aired cloches or greenhouses, encourage the condition, as does overcrowding, so airing the greenhouse well in winter and ensuring that plants are adequately spaced will help to arrest the problem. Any infected parts of plants should be removed and destroyed. Plants may also be sprayed with carbendazim or other systemic fungicide.