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Mycogone contamination aka wet bubble disease

Mycogone perniciosa contamination or wet bubble disease in mushroom growing
Wet bubble aka Mycogone contamination guide by Shroomok

Wet bubble or Mycogone contamination: how to identify, prevent and treat it

What is wet bubble disease?

This is a fungal disease caused by parasitic pathogen Mycogone perniciosa, that usually affected pinheads and mushroom fruitbody. It has a few often used names: mycogone, wet bubble, white mushroom mold, vesicular disease, La Mole.

It is one the most common problems of commercially cultivated edible mushrooms.

Mycogone perniciosa not known to be pathogenic to people or animals!

Usually we can find many examples of mycogone contamination from Agaricus bisporus mushroom farmers. Although wet bubble affected magic mushrooms, i.g. Psilocybe Cubensis quite often.

Let's figure out mycogone contamination in magic mushrooms cultivation, mostly for Cubensis.

Symptoms of wet bubble contamination

🔴 The early stage of Mycogone perniciosa is characterized by the development of dense white fluffy mycelial growth or wart-like growths, that usually appear on pinheads and mushroom fruiting bodies.

Symptoms of wet bubble disease in mushroom growing
White fluffy mycelial growth of Mycogone on all mushroom pinheads. Orange cycle - early mycogone contamination, red circle - late wet bubble disease


🔴 On the later stage of Mycogone contamination you can admit pins and mushrooms deformation or development of distorted masses of mushroom tissues, or fluffy blobs instead of normal pinheads and mushrooms. As a result pinheads and mushrooms can't develop at all

Pinheads and mushroom deformation as a symptom of wet bubble disease in mushroom cultivation
Pinheads and mushroom deformation as a symptom of mycogone perniciosa contamination in mushroom growing. Photo by Gorka on Shroomok Discord


🔴 The shapeless mass initially is white and fluffy, but become brown with age and then decay.

Wet bubble become brown with time and then decay
Mycogone blobs become brown with age and start to rot. Photo by Gorka on Shroomok Discord

🔴 On the late stage of wet bubble an amber liquid (yellowish, orange, brown) oozes from pins, blobs and mycelium clots

Yellow, brown, orange, amber liquid oozes from mushrooms, pinheads or mycelium clots is a sign of wet bubble disease


🔴 This fluid contains spores and bacteria that spread all over the mushroom cake and accompanied by objectionable odor, distinctive rotten smell. Although, the smell is imperceptible with a small area of ​​contamination

Mycogone contam on cubensis mushroom cake
Wet bubble disease spread over the Cubensis mushroom cake in monotub. Late stage of mycogone contamination. Photo by kp shrooms on Shroomok Discord

🔴 In dry conditions, the shapeless masses remain dry in appearance and similar to Verticillium contamination or Dry Bubble disease

How to recognize whether it's mycogone contamination or mycelium piss

Wet bubble contamination seems similar to mycelium metabolites, but Mycogon has some differences.

Mycogone usually appears on pinheads and mushrooms. Wet bubble creates a blob with porous surface, like a sponge. Look, each yellow-brown drop has its place. Usually this liquid is slimy and smelly.

How to recognize whether it's mycogone contamination or mycelium metabolites
Mycogone contamination or mycelium metabolites? Porous blob like a sponge with oozes yellow-brown liquid is wet bubble disease. Photo by Gorka on Shroomok Discord


Mycelium piss, also known as mycelium metabolites, usually appear due to stress on mushroom mycelium. Metabolites are transparent. Without any odor at all. Without slime, like water, but with yellow-brown color.

Mycelium metabolites
Mycelium piss due to stress and overlay

Mycelium piss is not a contamination itself and totally save.

🟠 Recommended guide: Mycelium metabolites or mushroom piss

Main causes of mycogone contamination

Mycogone contamination on cubensis mushroom cake
Wet bubble on mushroom cake, Psilocybe Cubensis growing

Mycogone perniciosa forms two kinds of spores:

🧬 conidiospores — unicellular, thin-walled spores, with a relatively short life, very light, therefore, they can be carried by air currents

🧬 chlamydospores — consist of two cells, thick-walled, brown spores, they stay viable for several years

The main Mycogone habitat is soil, that's why the main source of contamination is mostly the bulk substrate and casing substrate.

The disease can spread by spores and pieces of mycogone mycelium, adhering to any objects that touch the fungus (air flow, dust, tools, flies and mites, grower's hands and clothes).

Incubation period for Mycogone is two weeks. What does it mean?

If Mycogone appears during the first flush, then it spores were probably introduced via the bulk or casing substrate at the time of its application or during spawn run.

Later contamination (more than 2 weeks after spawn to bulk and casing, 2-3 flush) are more probably spread by air, grower's hand and clothes, insects etc.

Preventive measures of wet bubble disease

Substrate pausterization (sterilization) and sterility is a key!

Mycogone contamination
Mycogone contamination on P. Cubensis mycelium

✔️ Bulk and casing substrate pausterization in bucket. Spores of Mycogone perniciosa are killed at 120F or +49C and higher when exposed to moist heat (pasteurization) for 24 hours.

✔️ Bulk and casing substrate pausterization in the oven also works great (at least 160F or +70C for 1-2 hours).

✔️ Sterilized bulk and casing substrate (pressure cooker or autoclave at 15 psi for 1 hour). Although pausterization is preferable for bulk and casing.

✔️ Good fresh air exchange (FAE) in fruiting chamber. Stagnant air causes a wide range of contaminants.

✔️ Lowering temperature. Mycogone doesn't grow at temperatures lower than 60F or 15C. For many edible mushroom species it's a good point, however not for warm-loving magic mushroom species.

✔️ Strict hygienic conditions before and during any mycological manipulations (use sterile tools, wipe surfaces and tools with iso alcohol, wash your hands, wear gloves and face mask)

Wet bubble treatment

Mycogone is a vigorous and resilient contaminant. More effective to prevent this contamination than treat it.

Color as a symptom of mycogone contamination. Yellow, brown, orange, amber liquid oozes from mushrooms, pinheads or mycelium clots
Shapeless mass with rotted smell is a sign of late mycogone contamination

Small mushroom cakes or mushroom blocks in monotub usually have not so big surface as mushroom bed on the farms. If you have Mycogone on top layer probably the entire bulk substrate and/or casing layer is contaminated with Mycogone spores, if it is you can’t just scoop it out. It means Mycogone can appear again and again...That's why the most effective and popular advises here are: toss it immediately, bury in the backyard or burn it!

Let's look at the experience of mushroom farmers! Do they really burn mushroom blocks/beds with infected area size of a coin?

1) Non toxic, the most common method is used by mushroom farmers for Mycogone treatment (the size of a coin!)

Remove localised pieces of Wet Bubble disease carefully, using a disposable glove or plastic bag. Once in the bag or glove, carefully invert the bag or glove over it, close securely and dispose of safely.

Then the localized area is:

a) sprinkled with salt, baking soda or ground lime

Salt application. Credit: "Identification and control of Cobweb disease on mushrooms" by Helen Grogan, Teagasc and Richard Gaze, WHRI & ADAS

b) or watered with a formalin (formaldehyde) solution and then strewed with ground lime. These areas can be completely removed the next day, grasping the casing layer of a larger diameter.

❗️Don't mist/spray/water/rehydrate mushroom cake until the contaminated area is treated to avoid infection spreading all over the mushroom cake


In literature, the following recommendations for Mycogone prevention and treatment are given:

2) According to Kneebone (1961) he recommends the use of chlorinated water (150-250 ppm) for misting/watering to prevent Mycogone spores germination.

How to prepare 150-250 ppm Chlorinated Water?

Dissolve the bleach (Sodium Hypochlorite - NaOCl) in 1 liter of water according to these ratios:

  • NaOCl 5.25% (Amazon) - add 3.0-5.0 ml per 1L of water
  • NaOCl 6.0% (Amazon) - add 2.6-4.4 ml per 1L of water
  • NaOCl 7.5% (Amazon) - add 2.1-3.5 ml per 1L of water
  • NaOCl 12.5% (Amazon) - add 1.3-2.1 ml per 1L of water
  • Fill a spray bottle with the solution and spray it on casing surface.

3) Spray of Benomyl 0,1% (also marketed as Benlate) fungicide immediately after casing has been found one of the most effective (Gupta et al., 2018).

4) Application of fungicides: Carbendazim, Chlorothalonil, Prochloraz Manganese complex (Sportak 50 WP) 0,1% into casing material (Gupta et al., 2018).

5) A spray of 0,8% Formalin (formaldehyde) on casing surface, immediately after its application is also effective (Gupta et al., 2018).

If you find this guide helpful support my work and buymeacoffee

Feel free to ask your questions on Shroomok Discord or Reddit or in comments to this post ⬇️

Have a happy growing and healthy shrooms!

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