20/11/2025
Signs of contaminated substrate
Contamination can ruin your entire mushroom batch if you don’t catch it early.
Here are the top signs your substrate bag is no longer safe:
1. Green Mold (Trichoderma)
If you see green patches, powdery spots, or fast-spreading discoloration — that’s Trichoderma.
It competes with your mycelium and will completely take over the bag.
# Don’t hesitate. Remove and destroy the bag immediately.
If your bag smells fermented, sour, rotten, or chemical-like, it means bacteria have taken over.
# Such bags must be taken out fast to protect the rest of your farm.
3. Slimy or wet surface inside the bag
Slime = bacterial contamination.
Your mycelium cannot grow on a slimy substrate.
# Once slime appears, the bag cannot be rescued — dispose of it.
* Why you must remove contaminated bags quickly:
They spread spores and bacteria to healthy bags
They slow down colonization
They reduce yield
They attract flies and pests in your mushroom house
Save this post to check your next batch
Share with someone who’s starting mushroom farming.
