Grey mould
A fungal rot that covers flowers, fruit and soft stems with fuzzy grey mould in cool, damp conditions.
Also known as: Botrytis blight, Gray mold
Symptoms and identification
Brown, water-soaked spots on petals, fruit and leaves, which soon become covered in fluffy grey mould that releases dust-like spores when touched. Strawberries rot on the plant, and flower buds turn brown and fail to open.
Causes
Botrytis cinerea attacks dying or damaged tissue first, then spreads to healthy parts in still, humid air. Overcrowding and wet foliage favour it.
Organic treatment
Cut away and bin all affected parts. Improve airflow and reduce watering. A spray of Bacillus subtilis-based biofungicide can protect healthy flowers.
Prevention
Remove faded flowers and damaged leaves promptly, space plants well, and water the soil rather than the plant. Mulch strawberries with straw to keep fruit off wet soil.
Chemical treatment (use with care)
Fungicides labelled for botrytis can be used following the label; rotate active ingredients, as resistance develops quickly.