Grey mould or botrytis is a very common fungal disease caused by the fungus Botrytis cinerea, which can attack just about any plant. It produces a fuzzy grey fungal growth or mould on the leaves, buds, flowers and fruit of many plants. It is particularly common in damp or humid weather and on any plant grown under glass where conditions are very humid. It is also a common disease on very soft plant parts, particularly soft fruit, especially on gooseberries, grapes, raspberries and strawberries.
Affected buds and flowers may shrivel and die in severe attacks.
In low humidity conditions, infections may be limited to discrete spots, but in high humidity/damp conditions it can spread rapidly over the whole plant part or the whole plant.
Grey mould normally enters through a wound on leaves, stems and buds, but doesn’t need wounds on flowers and fruit. Or it infects plants under stress, but will attack healthy plants as well, especially under damp or humid conditions.
It is also usually worse on overcrowded plants, which prevents good air movement through the plant, so give plants plenty of space and under glass, ensure good ventilation.
It can attack plants at any time of year.
Other botrytis diseases
As well as Botrytis cinerea, there are several closely related Botrytis species that have specific host plants and produce specific disease symptoms.
Broad bean chocolate spot – Botrytis fabae and Botrytis cinerea
Peony wilt – Botrytis paeoniae
Snowdrop grey mould – Botrytis galanthina
Tulip fire – Botrytis tulipae