Notes from Windward: #68


Our First Shitake Mushroom

Kerst updates the mycology project

     I've got my first shiitake mushroom! I'll be the first to note that it's slightly ironic that I grew it unintentionally at an intentional community and hope that it's no indication of my mushroom cultivating abilities.

First Mushroom
spoon and housefly included for relative size

     The mushroom pictured actually grew off of a leftover block of sawdust spawn that has been kept in Walt's refrigerator since May. At that time we mixed most of the sawdust spawn in with oak wood chips in polypropylene bags suited with air filter patches as well as plugging oak logs with a different strain of spawn. Any additional spawn plugs were added to the 3 large beds of wood chips.

      When working with logs or such large quantities of wood chips, progress is slow to show. However, the growth of this mushroom gives me confidence that at least one of the strains of spawn we're using is viable. Rather than eating our first mushroom, I decided to use it to learn more about mushroom cultivation techniques practiced by home growers. If I'm able to produce additional batches of spawn from this mushroom, it will reduce the need to purchase spawn from outside sources. That being said, it's trickier said than done, especially when working in a non-sterile environment.

Kerst explaining to Oana that the spores
are released from the gills on the underside of the cap

     Ideally I would collect the spores from the gills on the underside of the mushroom cap and inoculate several petri dishes containing a nutrient rich agar medium. Lacking agar and petri dishes, I chose to take a "spore print," which is a technique that allows one to collect the spores to store for use at a later date.

examples of spore prints

     I placed one half of the mushroom on a piece of computer paper, gills facing down, and covered it with a glass bowl to minimize possibility of contamination overnight. Mature spores released in the following hours will deposit on the paper and leave a visible print such as the one below. The mushroom that I used was rather moist and did not produce a visible print but hopefully spores were released to attempt a culture when I have access to more growing materials.

spore printing our first mushroom

     For the remaining half of the mushroom I created a growing substrate from straw, wood chips and a growing medium (described below) that I modified from suggestions found in Paul Stamet's book The Mushroom Cultivator. After layering straw and then oak chips in two recycled 4lb plastic peanut butter containers, I added .5 c of the growing medium to absorb thoroughly but drained any excess liquid after 20 minutes to prevent non-desirable rotting (vs. mycilial growth followed by decay of substrate) that might occur in ultra moist conditions. Dicing the remaining mushroom half into about 16 equal pieces, including the stem, I distributed the mushroom evenly between the two jars and then covered with another layer of wood chips (~.5 c) followed by a layer of straw. The mouths of the jars are covered by a coffee filter to discourage bacterial and other fungal growth and loosely covered with lids.


Growth Medium

     Various recipes for agar media suggest the addition of broth from boiled poatoes and wheat or rye to stimulate mycelium growth. Because I don't have access to agar, I chose to incorporate these nutrients directly into the straw/wood substrate. I boiled 3 peeled potatoes and .5 c of rye berries until I had a fairly cloudy yellow liquid (40-60 minutes) which was strained, collected and cooled to room temp before adding to the straw and wood chips.

Notes From Windward - Index - Vol. 68