Black, Green and Other Mold on Mushrooms Mycelium

Can mushrooms get moldy? Even the best mushroom grower cannot guarantee a mold-free mushroom growing experience. For sure, they will encounter mycelium mold and even mold on mushrooms from time to time.

Expectedly, molds are every mushroom grower’s number one enemy mainly because of how fast they can spoil your crop.

From spores, molds grow and become noticeable within 24 hours.

The ideal growing condition for mushrooms invites different types of molds like:

1. Cobweb Mold (Hypomyces or Dactylium)
2. Green mold (Trichoderma)
3. Black mold (Stachybotrys)
4. Orange-red bread mold (Neurospora)
5. Black bread mold a.k.a pin head mold (Rhizopus)

Luckily, unlike other contaminations like bacteria and gnats, molds may be the simplest to treat. The key to treating mold on mycelium is by spotting them early on.

Mostly, all mushroom mold contaminations can be treated the same. That is if you are in the early phases of growing (before the fruiting body phase).

Now, the tricky part is identifying them and not mistaking them for other contaminations or as normal mushroom mycelium.

Do not worry as we will show you below what each mold contamination looks like and the different ways to treat them.

1. How to Spot Mold Contamination on Mushroom Mycelium

1.1 Cobweb Mold (Hypomyces or Dactylium)

Cobweb mold is a fast-growing mold with very fine white strands. For as short as 24 hours, it develops into a stringy gray mass.

Most of the time, it can be tricky to tell apart from the growing mycelium.

1.2 Green Mold on Mushrooms Substrate (Trichoderma)

Trichoderma spp., also known as green mold, frequently contaminates any type of mushroom substrates. Most probably, it is the most persistent and aggressive mushroom contaminant.

Usually, green mold begins growing on white mycelium with white or off-white color, maturing into olive color to dark green.

How to Get Rid of Green Mold on Mycelium

The fastest and strongest solution to get rid of the green mold spores is mixing laundry bleach, water, and vinegar.

Firstly measure a 1:10 ratio of laundry bleach. Then add it to water.

Mix all together and then combine the ingredients with the same ratio of vinegar.

Pour all into a little spray container and spread it all over the affected air area.

1.3 Black Mold on Mushrooms (Stachybotrys)

Black mold appears slimy black or highly dark gray, like black crayons on paper.

Also, this mold tends to have definite round splotches with a mottled appearance. Often, you see darker layers of mold over lighter layers.

Black mold is also a common problem in U.S. households. It is often attributed to water damage or leak. When it gets out of hand, homeowners could use some help from mold remediation service providers.

As a matter of fact, who would like to grow mushrooms in a mold-contaminated household? Mold spores are everywhere!

1.4 Orange-Red Bread Mold on Mushroom (Neurospora)

Orange and red bread mold appears irregularly cushion-shaped and soon becomes effuse and fluffy. Its color ranges from pale salmon, and orange, to red.

1.5 Black Bread Mold, a.k.a Black Pin Mold (Rhizopus)

Rhizopus is a common mold that grows on bread. It looks like a grayish fluffy mass and can be easily confused with Cobweb mold.

Over time, as Rhizopus begins to produce spores, the sporangium (the capsule structure appearing like a pin) becomes black.

2. How to Treat Contamination

2.1 Spray Hydrogen Peroxide ( H₂O₂)

Undeniably, hydrogen peroxide is an effective way to treat the early stages of mold. That is within 24 hours since visible mold contamination.

Oftentimes, mushroom cultivators advise spraying the surface mold with 3% hydrogen peroxide.

Fortunately, you do not need to create your solution since you can just buy over-the-counter. Hydrogen peroxide is sold in concentrations of 3 to 12 percent at most drug stores and online stores.

For this, you may use a clean spray bottle. Simply spray the whole surface area of your infected substrate or fruiting block with the solution.

In a blink of an eye, molds dissolve as they come in contact with the solution.

2.2 Isolate and Scoop Out the Contaminated Area

Before scooping any contaminated area of your crop, the first best thing to do is separate the mold-contaminated kit from healthy ones (supposing you have more than one grow kit).

However, scooping out the contaminated area of your crop seems like a desperate measure. Mold spores like Trichoderma are hard to contain once it gets ahold of your crop.

But if you’d like to take a chance with your mold-contaminated kit, you can try the following:

1. Prepare your spoon (clean it with 70% isopropyl alcohol).
2. Spray hydrogen peroxide on the surface of the crop.
3. Put a clean damp paper on the mold blotch.
4. Scoop it with your clean spoon.

If the mold on mycelium is smaller than a coin, your chance of saving your kit with the scoop-out method is higher.

2.3 Throw Your Mushroom Mycelium Block… Under a Tree

This may sound silly, but it sometimes works. Well, since you’ll throw it, you might consider giving it some dignity. lol

So instead of putting your contaminated mushroom block in a garbage can, you may put it in a proper resting place, under a tree or a pile of wood in your backyard.

Try to think of it. Mushrooms that grow in the wild need not have careful babysitting. They just thrive amidst all environmental challenges. Thus, the same thing may happen with your spoiled mushroom block.

Besides, if you give it a chance to flourish in its natural habitat, it may have a bigger chance of surviving. So just toss it under a tree and come back a week later to see if it has returned to life. 😉

Now, you have an idea of spotting these silly mold contaminants.

As a recap, the most common are green mold, black mold, orange bread mold, pinhead mold, and cobweb mold.

In addition, you can treat your contaminated block by spraying hydrogen peroxide, scooping out contaminated areas, or tossing it with dignity under a tree.

Always remember: once you spot contamination, immediately separate the healthy blocks. Also, in using any tools that will touch your substrate, sterilize them first with isopropyl alcohol or flame.*

Happy Mushroom Growing! 🙂