Symptom
Fuzzy mould
Fuzzy growth is a fungus or water mould in fruiting mode. Grey fur on fruit is botrytis; grey-purple down under leaves is downy mildew; white fluff on compost is often harmless or damping off.
Where the fuzz is tells you most: on fruit, under leaves, or on the compost.
Likely causes
Ordered from the usual answer to the less likely one. Each links to the full problem.
-
Fungal disease Common
Grey mould (botrytis)
Grey fur on fruit and flowers that puffs spores. -
Fungal disease Possible
Downy mildew
Grey-purple down under yellow patches on leaves. -
Fungal disease Possible
Damping off
White fluff on compost with collapsing seedlings. -
Fungal disease Less likely
Sooty mould
Black, not fuzzy; wipes off.