Grey Mould (Botrytis) is a common disease that affects strawberries, raspberries, french beans in Scotland. Here is what it looks like, the conditions it needs, and the controls that actually work.
What does it look like?
Fuzzy grey-brown mould on decaying plant parts; shrivelled buds and flowers that die; small black seed-like structures (sclerotia) on infected material; soft brown decay on fruits such as strawberries; and branch death on cane fruits.
This pest is active year-round under cover: there is no seasonal break.
🌱 Plants at risk
Grey Mould (Botrytis) also affects these crops in our grow guide:
Life cycle
Airborne spores are always present. The disease can occur year-round and may cause latent infections that do not show symptoms immediately.
Why this matters in Scotland
A wet-climate disease that Scottish growers meet twice — outdoors on soft fruit, and under cover where the polytunnel that protects tomatoes from blight creates the humidity botrytis wants.
High humidity and poor ventilation are the drivers. Scotland supplies humidity outdoors, and our tomato guide records that Scottish tomatoes are grown under cover almost by necessity. That cover is humid, which is the same mechanism the tomato blight entry flags: enclosure trades fewer arriving spores for better conditions for anything already inside. Ventilation is therefore the single lever that works against botrytis, against powdery mildew, and against blight's rapid development if it breaches a tunnel.
Controls: what actually works
Every method below is graded by evidence, not by how often it gets repeated. Where a claim has been tested and failed, we say so plainly.
Chemical control
No fungicides are currently approved for gardeners to use against grey mould.
What actually works: No fungicide will touch grey mould, so ventilation is the real control: improve airflow, avoid overcrowding, and clear dead or dying material promptly, before it becomes the next spore source.
Reduce humidity through improved ventilation; avoid overcrowding plants
Reduce humidity by improving ventilation, and avoid overcrowding plants.
Ties directly to the spacing figures in our crop guides — spacing is not only about yield, it is a disease control.
Remove dead and dying plant material promptly; dispose of infected parts carefully to prevent spore dispersal
Frequently asked questions
What should I do first if I find grey mould (botrytis) in my garden?
Start with reduce humidity through improved ventilation; avoid overcrowding plants. After that, remove dead and dying plant material promptly; dispose of infected parts carefully to prevent spore dispersal. The full list of evidenced controls is above, each graded by how much evidence supports it.
Is there a spray that works?
No. There are no amateur fungicides available for grey mould (botrytis). The controls that work are cultural: the measures listed above.
Sources
1 source, recorded with what each was used for
- RHS1: organism and ubiquity, symptoms including sclerotia and soft brown fruit decay, humidity/ventilation/overcrowding drivers, infection without wounds, year-round occurrence and latent infection, no approved fungicides, cultural measures