Cobweb Mould
A fast, grey, wispy mould that spreads across the substrate surface. It is one of the few contaminants that is treatable if caught early.
What it is
Cobweb mould is a fast-growing grey, wispy mould that spreads across a substrate surface. It is one of the few contaminants that is sometimes treatable if you catch it early.
How to spot it
It looks like a thin, fuzzy grey cobweb that grows outward much faster than mushroom mycelium and looks softer and greyer. It can cover a surface within a day.
Prevention
Cobweb mould is linked to high humidity and low fresh air, so improve air exchange and avoid standing water on the surface. Keep the grow space clean and do not let humidity sit too high without ventilation.
What to do
Caught early, mist the spot directly with 3% hydrogen peroxide and increase fresh air exchange, which often stops it. Lower the surface humidity a little. If it has spread widely, it is safer to discard the block.