Botrytis or grey mould is a fungal disease that affects healthy plants as well as those under stress. It mainly tends to affect damaged plants and seedlings. It takes hold by entering through the wound and then spreading to other parts of the plant.
It’s is very often found on lettuce but can affect other vegetables and fruit such as courgettes, cucumber, tomatoes, grapes, strawberries, and raspberries. It can also infect ornamental plants such as pelargonium, chrysanthemum, and cyclamen.
Both seedlings and mature plants are susceptible, especially if they’re overcrowded and being grown in a humid greenhouse.
It can strike at any time of the year but is more prevalent during the summer months. Plants grown in stressed conditions, as in a greenhouse, or outside in humid conditions with poor air circulation are particularly susceptible.
The first signs of infection are parts of the plant turning brown and soft and then becoming covered in a grey-brown fluffy mould. Seedlings can suddenly collapse as the fungus spreads to their young stems. On older plants, buds and flowers may also shrivel up and die off.