🐛✗ Tested and false“Cutting off and binning affected leaves or fruit stops grey mould spreading”
Removing infected material is worth doing, but it does not stop spread on its own, because the plant is releasing spores into the air the whole time it sits there and again in the act of removing it. Grey mould's spores are airborne and always present in the environment; picking an infected leaf or fruit disturbs the mould and can visibly release a cloud of spores at the moment of removal. Sanitation is a slow-down measure, not a seal.
Our read RHS treats grey mould's spores as constantly airborne and notes they disperse very easily; a US extension guide describing the same fungus records a visible cloud of spores released when infected leaves or flowers are picked, while still recommending removal as part of a wider routine.
What to do: Keep removing dead and infected material promptly as one part of the routine, but pair it with better spacing and ventilation; don't treat a clean-up as having solved the problem.
In Scotland: Under cover, where a polytunnel or greenhouse traps humidity, spores released during removal have nowhere to disperse to and can simply resettle on the next plant along, so ventilation matters as much as the clean-up itself.
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“Spraying a fungicide is the best way to deal with grey mould”
For a UK amateur gardener this isn't an option worth reaching for, because there is nothing approved to reach for. No fungicide products are currently approved for gardeners to use against grey mould, which makes ventilation, spacing and prompt removal the entire toolkit rather than one option among several.
Our read RHS states plainly that no fungicides are approved for use against grey mould by gardeners.
What to do: Skip the fungicide aisle for this one and put the effort into airflow, spacing and hygiene instead, since that is the only control available.
In Scotland: Home garden centres sometimes stock general-purpose fungicides that claim broad disease control; none of them carries UK amateur approval for grey mould specifically, so label claims for other diseases shouldn't be read as covering this one.
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- RHS: Grey mouldNo fungicides are approved for use against grey mould by gardeners.
“Grey mould only gets into plants through wounds or damaged tissue, so undamaged plants are safe”
It depends which part of the plant. On leaves and stems, a wound or some other stress is usually needed before the fungus can get a foothold. On flowers and ripening fruit, that protection doesn't apply: the fungus can infect through completely intact tissue, especially once humidity is high. A grower who only checks for nicks and bruises before worrying about grey mould is applying a rule that holds for foliage but not for the flowers and fruit where the disease usually shows up first.
Our read RHS is explicit that grey mould 'normally enters through a wound or infects plants under stress, but will infect healthy plants as well, especially under humid conditions,' and separately that on flowers and fruit it infects readily without any wound.
What to do: Treat humidity and airflow as the real defence rather than relying on tissue being intact; inspect flowers and ripening fruit even on plants with no visible damage.
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- RHS: Grey mouldGrey mould normally needs a wound or stressed tissue to establish on leaves and stems, but infects flowers and fruit without any wound under humid conditions.
“Grey mould on strawberries, lettuce and tomatoes is really the same disease, just showing up on different crops”
It is one organism, Botrytis cinerea, with an unusually wide host range rather than a family of crop-specific look-alikes. The same fungus is behind the grey fuzz on strawberries, the collapsed stems on lettuce, the ghost-spotting and stem rot on tomatoes, and the die-back on cane fruit. That matters practically: conditions that favour it on one crop favour it on the others growing alongside it, and a bad infection on one susceptible plant is a spore source for its neighbours regardless of species.
Our read RHS describes Botrytis cinerea as having a very wide host range, distinct from related Botrytis species that are limited to single hosts like snowdrops or onions, and lists soft fruit, beans, cucumber, courgettes, lettuce and tomatoes among the crops it affects. A US extension factsheet on the same fungus separately lists flowers, fruit and vegetables spanning from begonias to beans as susceptible hosts.
What to do: Manage grey mould at the bed or polytunnel level rather than per crop: spacing and ventilation improvements benefit every susceptible plant nearby, not just the one showing symptoms.
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- RHS: Grey mouldBotrytis cinerea has a very wide host range, unlike related Botrytis species restricted to single hosts, and affects soft fruit, beans, courgettes, lettuce and tomatoes among others.
- Clemson HGIC: Gray Mold (Botrytis Blight) on Flowers, Fruits, and VegetablesGray mold caused by Botrytis cinerea affects a wide range of flowers, fruits and vegetables including strawberries, grapes, beans and tomatoes.
“Watering over the leaves and flowers, rather than at the base, makes grey mould worse”
Wetting foliage and flowers gives the fungus two things it needs: standing moisture to germinate spores in, and splashes that carry spores from an infected leaf to a healthy one. This sits alongside humidity and overcrowding as one of the practical, controllable drivers of infection, distinct from general air humidity, which a gardener can't easily change but watering method they can.
Our read A US extension factsheet on the same fungus recommends avoiding overhead watering because the disease spreads easily by splashing water. RHS's own guidance names high humidity and poor ventilation as the main drivers, which is consistent with wet foliage adding to the risk rather than being a separate issue.
What to do: Water at the base of the plant, ideally in the morning so any splash that does occur has the day to dry off, rather than overhead or in the evening.
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