Managing Unwanted Fungus

Humid environment, limited air flow, block of substrate ideal for growing a fungus - of course there will be undesirable molds showing up!

See that grayish area?

How about that shiny white spot?

I've been misting twice a day to help keep the surface damp and encourage growth of the shiitake. Before misting I always look for signs of mold. Once I spot it, I quickly try to stop it from growing further. After all, I don't want to wind up with some type of toxic fungus on my edible fungus.

How to get rid of it? Spot treat with vinegar. Remember back to high school chemistry and talking about acids and bases? Vinegar consists of acetic acid. Acid kills things. The same way organic gardeners and farmers may use vinegar to help control weeds (and you thought organic gardening didn't use chemicals - ha!).

A little vinegar, a little paper towel, and a little dab 'll do ya! Actually, you can see discoloration on the paper towel from when I was treating the white shiny spot - a normal block surface will not discolor the paper towel.

Here's another view. The blackish areas on the right were treated with vinegar the day before. The grayish spot was hidden by some broad mushrooms but now that they have been picked I know exactly where to treat. 

Here's the underside of the block. Remember, this area doesn't get much air flow and because it sits right above the drip tray it has constantly high humidity.

It might take a couple treatments with vinegar to kill all of this off. I don't want to re-soak the block and start another cycle if I have undesirable fungi growing there.