Contamination Guide
When you're growing mushrooms, contamination is something that can happen, even if you're super careful. It’s like getting an infection in a cut—no matter how clean you keep things, germs can still sneak in. The trick is to reduce the chances of contamination and deal with it quickly when it shows up.
What is Contamination?
Contamination is anything that gets into your mushroom-growing setup that you don’t want, like mold or bacteria. These unwanted guests can cause big problems because they can spread really fast. If you spot contamination, you need to separate the bad stuff from the good stuff and get rid of it ASAP.
How to Spot Contamination
It’s usually easy to spot contamination because it changes the color of your mushrooms or their growing medium (the stuff they grow in). If you see patches of green, blue, gray, or black, that's a bad sign. But watch out! Sometimes blue spots are just bruises on the mycelium (the mushroom "roots") and not mold. To check, gently wipe the spot with a cotton bud. If it’s mold, the color will come off on the Q-tip. If it’s just a bruise, nothing will come off.
Another sign of contamination is slimy patches on your growing medium or mycelium. This usually means there's too much moisture and bacteria are starting to grow.
Common Types of Contamination
Trichoderma (Green Mold)
What it looks like: Trichoderma is the most common contaminant in mushroom growing. It’s usually blue-green and grows really fast. It can be hard to spot early because it looks like mushroom mycelium, but it’s fluffier. Once it turns green and starts spreading spores, it’s time to get rid of it fast before it contaminates everything else.
What to do: Move anything contaminated far away from your other mushrooms and clean the area thoroughly before starting again.
Bacterial Contamination ("Wet Spot" or "Sour Rot")
What it looks like: If you see dull gray slime and your mushrooms smell sour, that’s bacteria. It makes everything look wet and gross.
How to prevent it: Before growing, soak your grains for 24 hours. This helps to kill the bacteria during sterilization (heating to kill germs). If you skip this step, some bacteria might survive.
Cobweb Mold
What it looks like: Cobweb mold looks like... well, cobwebs! It's light gray and can be mistaken for mushroom mycelium, which is bright white. Cobweb mold is wispy, while mycelium is more like ropes.
What to do: If you catch it early, spray the mold with hydrogen peroxide—it kills the mold but won’t harm the mushrooms. Also, lower humidity and improve air circulation to prevent it from spreading.
Orange Bread Mold
What it looks like: Orange bread mold is super bright and orange. It starts off looking like a fine, orange fuzz but quickly turns into a thick, powdery patch.
What to do: Seal anything with orange bread mold in a plastic bag and throw it out immediately. Clean the area well to stop it from spreading.
Black Bread Mold (Pin Head Mold)
What it looks like: This mold looks similar to cobweb mold but has tiny black dots. It’s often found on old bread but can also show up in your mushroom setup.
What to do: If you see black bread mold, toss the contaminated block right away. It can be dangerous, especially if someone breathes in the spores or eats mushrooms that grew near it.
If you have more questions or need assistance, feel free to get in touch!