Fungus Gnats and Mites
Pests rather than moulds, but a common fruiting-room problem. They feed on mycelium and can carry contamination between blocks.
What it is
Fungus gnats and mites are pests rather than moulds, but they are a common problem in fruiting rooms. They feed on mycelium and can carry contamination from block to block.
How to spot it
Fungus gnats are small dark flies seen around damp substrate, and their larvae tunnel through mycelium. Mites are tiny and hard to see, but a stalled or patchy grow with fine dust or webbing can be a clue.
Prevention
Keep the grow space clean, screen air intakes, remove spent blocks promptly, and avoid letting old, contaminated material sit around. Good hygiene and quick removal of finished blocks break the cycle.
What to do
Isolate and remove affected blocks, deep clean the room, and improve screening and airflow. Sticky traps help you monitor and reduce adult gnats. Prevention through cleanliness is far more effective than treating an outbreak.