Grey mould
Soft fruit turning brown and collapsing under a fuzzy grey coat, often overnight in wet weather. It is the single biggest cause of strawberry losses in a wet British summer, and it infects at flowering rather than when the mould appears.
Caused by: Botrytis cinerea · also called botrytis
Described view
Strawberry foliage and fruit in one frame: a berry and adjoining leaf tissue carrying the dense grey-brown fur of botrytis with the tissue beneath collapsed, and separately a leaf with dry, sharply-edged brown scorch along the margin and between the veins with no fungal growth on it at all
What brings it on
Cool damp weather and still air. The fungus infects through the open flower and stays latent in the developing fruit, which is why the mould appears suddenly on fruit that looked sound — and why anything done at picking time is already too late.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Grey mould (botrytis)
- University of Minnesota Extension — University of Minnesota: Grey mould of strawberry
Checked 2026-08-13
Usually seen: May, June, July, August, September
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Keep fruit off wet soil and air moving through the plants. Straw under strawberries, generous spacing, and removing old leaves after flowering all do more than anything applied later.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Strawberry cultivation
Checked 2026-08-13
- Pick over the crop every day or two in wet weather and remove every mouldy fruit. One infected berry left in place seeds the ones around it.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Grey mould (botrytis)
Checked 2026-08-13
- Avoid overhead watering while the crop is ripening, and water in the morning so foliage dries.
source
Horticultural consensusmoderate confidence
- University of Minnesota Extension — University of Minnesota: Grey mould of strawberry
Checked 2026-08-13
Dealing with it once it is there
- Remove and dispose of infected fruit rather than dropping it between the plants. Improve airflow by thinning growth where it can be done without losing the crop.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Grey mould (botrytis)
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.