Contamination, or ‘contam’ as we like to call it, can be caused by unwanted bacteria, molds, or pests that can negatively impact your crop. But don’t worry, we’re here to help!

The Basics

Let’s start with the basic signs of contamination to look out for: discoloration, off-odors, abnormal growth, presence of molds, and presence of insects. If you notice any of these signs, it’s important to take action right away to prevent further contamination. You might need to get rid of your tubs or jars, disinfect your growing area, or adjust your growing conditions.

Now, when it comes to preventing contamination, the most important thing is proper sterile technique. This means maintaining a sterilized environment throughout the entire cultivation process. Using sterilized equipment, growing mushroom spawn on sterilized substrates, and keeping a clean and controlled environment are all crucial.

The Sources

One common source of contamination is airborne spores. Fungi release spores that can remain viable for a long time and spread through the air. To reduce unwanted spores in your workspace, you can use a laminar flow hood or a still air box. These tools are especially helpful for medium to large-scale operations.

Another source of contamination is from the substrates themselves. Mushroom substrates are a breeding ground for unwanted microbes. If they’re not properly treated through pasteurization or sterilization, your desired fungi can be outcompeted. So, make sure to pasteurize or sterilize your substrates according to the needs of the specific mushroom species you’re growing.

Human-borne contamination is also a major concern. Our bodies are full of bacteria and spores that can ruin a crop, so make sure to shower, use hand sanitizer, wear clean clothes, a face mask, and laboratory gloves. It’s also a good idea to avoid talking or opening your mouth when working near open containers.

Bruise Clues

Now, when it comes to identifying contamination, it usually takes the form of green, blue, gray, or black patches or discolorations on the surface of your substrate. But don’t worry, sometimes blue stains on mycelium are just natural bruising and not contamination. One easy way to tell is by gently wiping a Q-tip over the area, as contamination will transfer to the swab while bruising will not.

We hope these tips help you prevent contamination and keep your mushroom crop healthy and thriving!

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