Growing Troubleshooting

Mycelium Bruises or Mold Contamination

Why magic mushrooms turned blue and have bruises? Why mycelium bruised? The main differences between bruising and mold contamination in mushroom growing

Why magic mushrooms and mycelium turned blue and bruised

What is mushroom bruising?

Fist of all you need to know it is not contamination! This reaction is of great interest to chemists. Because exact cause of mycelium bruising is still not well studied yet.

It is believed the main cause of mycelium and mushrooms bruises is oxidize. As you know, magic mushrooms contain psilocybin and psilocyn. These are the main alkaloids.

In the presence of oxygen psilocybin is more stable. But psilocyn readily forms bluish and dark-blue decomposition products. The bluish reaction or bluish-green is obvious in the most potent species. The less psilocyn there is in a species, the more subtle the bluish reaction.

Mushroom bruising
If you cut the mushroom bruises appear after a few seconds

Bruising is the reaction between psilocyn and oxygen. It’s not contamination!

Such mushroom reactions could be on the mycelium and on the fruit bodies. Blue color, blue-green or even black bruises is one of the signs of psilocybin mushrooms.

APE mushroom bruises
APE mushroom bruises

It is also found out that not only exposure to oxygen cause mycelium or mushrooms bruises. Another cause for the mycelium bruising is believed to be the presence of a metal ion like copper in the mycelium. This may be the reason why some non-psychoactive mushrooms get bruised as well

Why bruises appear during fruiting period?

Bruising is a result of mechanical impact, when cell walls of mycelium or mushroom tissue are damaged

🔵 If you touch the mushroom body or mycelium

Mycelium bruising
Mycelium bruises

🔵 After shaking the jar/bag with mushroom spawn

🔵 Hard misting. Water drops rolled down the mushroom body and influence the mushroom tissue or mycelium

Bruises after hard misting directly on mycelium
Mycelium bruising after hard misting (directly on mycelium). Photo by u/bluesplatema - Shroomok Community on Reddit

🔵 Hard fanning, when air currents can irritate mushrooms or mycelium

Real case: My fungi and mycelium turned a blue color about 2 hours after I misted them and lightly fanned. What’s going on here?

Bruises on psilocybin mushrooms after misting and fanning
Bruises on psilocybin mushrooms after hard misting and fanning

This case is a good example of hard fanning and misting. You can see bruises from the one side of mushroom stem, where air flow or water spraying irritated mushroom "skin"

🔵 Extreme bruising is normally found on harvested mushrooms, their stems and stumps

Bruises on mushroom stem after harvesting
Bruises on mushroom stem after harvesting

🔵 Bruising because cake and mycelium dehydrated or after water puddles on top layer. In this case mycelium dry out, loses its flexibility and becomes "brittle". Dehydration bruising is often widespread on the mycelium or around the base of pins and around the base of mushrooms

Mycelium bruising, top layer dry out and provoke bruising
Mycelium bruising, top layer dry out and provoke bruising

🔵 Mycelium bruises on agar, when you cut a piece of mycelium for agar transfer

Bruises on mycelium after agar transfer
Blue mild bruises on mycelium after agar transfer. Photo by TRYPTO - Shroomok growers Community in Discord
Mycelium bruising on agar
Mycelium bruising on agar. Photo by TRYPTO - Shroomok growers Community in Discord


🔵 Bruises on dry mushrooms

Mushroom bruising on dry magic mushrooms
Mushroom bruising on dry magic mushrooms

Is bruised mycelium and fruit bodies bad?

Bruising is not contamination. But it is often bruised damaged parts of the mycelium won't produce mushrooms. Sometimes mycelium can recover damaged parts. The parts of the mycelium which aren't damaged can still be producing healthy mushrooms.

Extreme bruising on mushroom bodies during fruiting period influences their development and potency.

Bruising during picking/harvesting mushrooms is impossible to avoid and this is absolutely normal!

Bruises on mushroom stem during harvesting
Bruises on mushroom stem during harvesting

How to avoid and what to do with bruising?

🔷 Be gentle with your mycelium and mushrooms. They are super sensitive!

🔷 Don’t touch mushrooms and mycelium during fruiting period

🔷 Don’t spray on the mycelium and mushrooms directly! If you maintain high humidity of the fruiting chamber by spraying it with water, spray on the walls of the tub only. Use ultra fine mister

🔷 Don’t turn on the fan very hard. It will be enough to open your tub for 5 minutes or use PC fan on slow mode and gently introduce fresh air

🔷 In case of mycelium bruising because of dry mycelium your mushroom cakes need rehydration and proper relative humidity in fruiting chamber (not less than 90%)

Bruising or Mold? Find the difference

Bruises and Green mold Trichoderma

It's always confused newbie growers, because green mold Trichoderma spp. (T. harzianum, T. viride, T. koningi) have white then green color

Trichoderma mold contamination in mushroom growing
Trichoderma mold contamination
Mushroom bruises and Trich mold
Mushroom bruises and Trichoderma mold


All in one: mycelium bruising (blue) and trich mold (green) on mushroom cake

Trich (green) and mycelium bruises (blue) on mushroom cake
Trich (green) and mycelium bruises (blue) on mushroom cake
Trichoderma mold
Trichoderma mold with powdery (green) and marshmallow (white) texture

🔴 All about Green Mold: Green mold contamination aka Trichoderma

Bruises and blue-green mold Penicillium

Blue-green mold Penicillium spp. also have blue-green color

Blue mold contamination (Penicillium)
Blue mold contamination (Penicillium)

❗️Remember, the main hallmark of molds (Trich, Penicillium) is a powdery and/or marshmallow texture

Bruising on mycelium that hard to identify

Bruised not contaminated mycelium can also have greenish tinge. Here was the most difficult case for identification bruises, take a look!

Mycelium bruising or contamination
Mycelium bruising or mold contamination? It's bruising!


From this photo (another side, same area) much easier to identify mycelium bruises. Here you can see mushroom mycelium threads turned blue, without powdery or marshmallow texture

Psilocybe mushroom bruising
Mild bruises of magic mushroom mycelium. Such bruising easy to confuse with mold

Q-Tip Test or Swab Test for mold identification

Q-tip test isn't scientific test, but popular lifehack among newbie mushroom growers.

Swab test can be used to determine whether your mycelium is just bruised or contaminated with mold (green mold Trichoderma spp. or blue mold Penicillium spp). This test is possible to use during fruiting period only. The test is based on the fact that mold spores are sticky and would be stuck on any surface that comes into contact.

To do this you have to take a clean white cotton swab or a fresh Q-tip and swipe it across the contaminated area. If your cotton swab rubs the blue or green powder on to it, it is highly likely that you are looking at a Trich or Penicillium contamination. If your cotton swab comes out clean without any color on it, your mycelium may be simply bruised.

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Have a happy growing and healthy shrooms!

  1. Growing Troubleshooting
  2. Bruises or contam?