Spore Mass Inoculation

By far the simplest way to grow mushrooms is to broadcast spores onto prepared substrates outdoors. First, spores of the desired species must be collected. Spore collection techniques vary, according to the shape, size, and type of the mushroom candidate.

For gilled mushrooms, the caps can be severed from the stems, and laid, gills down, on top of clean typing paper, glass, or similar surface. (See Figure 15.) A glass jar or bowl is placed over the mushroom to lessen the loss of water. After 12 hours, most mushrooms will have released thousands of spores, falling according to the radiating symmetry of the gills, in an attractive outline called a Spore Print. This method is ideal for mushroom hunters "on the go" who might not be able to make use of the spores immediately. After the spores have fallen, the spore print can be sealed, stored, and saved for future use. It can even be mailed without harm.

By collecting spores of many mushrooms, one creates a Species Library. A mushroom hunter may find a species only once in a lifetime. Under these circumstances, the existence of a spore print may be the only resource a cultivator has for future propagation. I prefer taking spore prints on a pane of glass, using duct tape as binding along one edge. The glass panes are folded together, and masking tape is used to seal the three remaining edges. This spore book is then regis tered with notes written affixed to its face as to the name of mushroom, the date of collection, the county and locality of the find. Spores collected in this fashion remain viable for years, although viability decreases over time. They should be stored in a dark, cool location, low in humidity and free from temperature fluctuation. Techniques for creating cultures from spores are explained further on.

Spore Mass Inoculation
Figure 15. Collecting the spores of the delicious Lepiota rachodes, a Parasol Mushroom, on two panes of glass which are then folded together, creating a Spore booklet.

For those wishing to begin a mushroom patch using fresh specimens, a more effi cient method of spore collection is recommended. This method calls for the immersion of the mushroom in water to create a spore mass slurry. Choose fairly mature mushrooms and submerge them in a 5-gallon bucket of water. A gram or twc of table salt inhibits bacteria from growing while not substantially affecting the viability of the spores. By addir.g 50 ml. of molasses, spores are stimulated ;nto frenzied germination. After four hours of soaking, remove the mushroom(s) from the bucket. Most mushrooms will have released tens of thousands of spores. Allow the broth to sit for 24-48 hours at a temperature above 50° F. (10° C.) but under 80° F. (27° C.) In most cases, spores begin to germinate in minutes to hours, aggressively in search of new mates and nutrients. This slurry can be expanded by a factor of ten in 48 hours. (I

have often dreamed, being the mad scientist, of using spore mass slurries of Morels and other species to aerially "bomb" large expanses of forest lands. This idea, as crazy as if may initially sound, warrants serious investigation.)

During this stage of frenzied spore germination, the mushroom patch habitat should be designed and constructed. Each species has unique requirements for substrate components for fruiting. However, mycelia of most species will run through a variety of lignin-cellulosic wastes Only at the stage when fruitbody production is sought does the precise formulation of the substrate become crucial.

Oyster (Pleurotus ostreatus, P. eryngii and allies), King Stropharia {StropHaria rugoso-annulata), and Shaggy Manef Coprinus comatus) mushrooms thrive in a broad range of substrate formulations. Other mushrooms such as Morels (Morchella angusticeps & esculenta) are more restrictive in their requirements. Since there are several tracks that one can pursue to create suitable habitats, refer to Chapter 21 for more information.

Transplantation is the moving of mycelium from natural patches to new habitats. Most wild mushroom patches have a vast mycelial network emanating beneath each mushroom. Not only can one harvest the mushroom, but portions of the mycelial network can be gathered and transferred to a new location. This method ensures the quick establishment of a new colony without having to germinate spores or buying commercial spawn.

When transplanting mycelium, I use a paper sack or a cardboard box. Once mycelium is disturbed, it quickly dries out unless measures are taken to prevent dehydration. After it is removed from its original habitat, the mycelium will remain viable for days or weeks, as long as it is kept moist in a cool, dark place.

Gathering the wild mycelium of mycorrhizal mushrooms could endanger the parent colony. Be sure you cover the divot with wood debri s and press tightly back into place. In my opinion, mycorrhizal species should not be transplanted unless the parent colony is imminently threatened with loss of habitat—such as logging, construction, etc. Digging up mycelium from the root zone of a healthy forest can jeopardize the symbiotic relationship between the mushroom and its host tree. Exposed mycelium and roots become vulnerable to cisease, insect invasion, and dehydration. Furthermore transplantation of mycorrhizal species has a lower success rate than the transplantation of saprophytic mushrooms.

If done properly, transplanting the mycelium of saprophytic mushrooms is not threatening to naturally occurring mushroom colonies. Some of the best sites for finding mycelium for transplantation are sawdust piles. Mycelial networks running through sawdust piles tend to be vast and relatively clean of competing fungi. Fans of mycelium are more often found along the periphery of sawdust piles than within their depths. When sawdust piles are a foot deep or more, the microclimate is better suited for molds and thermophilic fungi. These mold fungi benefit from the high carbon dioxide and heat generated from natural composting. At depths of 2-6 inches, mushroom mycelia runs vigorously. It is from these areas that mushroom mycelium should be collected for transplantation to new locations. One, in effect, engages in a form of mycelial mining by encouraging the growth and the harvesting of mycelium from such environments. Ideal locations for finding such colonies are sawmills, nurseries, composting sites, recycling centers, rose andrhododendron gardens, and soil mixing compa res.

In the early history of mushroom cultivation, mycelium was collected from the wild and transplanted into new substrates with varying results. Soon compost spawn (for the Button Mushroom (Agaricus brunnescens ) evolved with greater success. In 1933, spawn technology was revolutionized by Sinden's discovery of grain as a spawn carrier medium. Likewise, Stoller (1962) significantly contributed to the technology of mushroom cultivation through a series of practical advances in using plastic bags, collars and filters* The Mushroom Cultivator (Stamets and Chilton, 1983) decentralized tissue culture for spawn generation, empowering far more cultivators than ever before Legions of creative individuals embarked on the path of exotic mushroom production. Today, thousands of cultivators are contributing to an ever-expanding body of knowledge, and setting the stage for the cultivation of many gourmet and medicinal fungi of the future.

The advantage of using commercial spawn is in acquiring mycelium of higher purity than can be harvested from nature. Commercial spawn can be bought in two forms: grain or wood (sawdust or plugs). For the inoculation of outdoor, unpasteurized substrates, wood-based spawn is far better than grain spawn. When grain spawn is introduced to an outdoor bed, insects, birds, and slugs quickly seek out the nutritious kernels for food. Sawdust spawn has the added advantage of having more particles or inoculation points per lb. than does grain. With more points of inoculation, colonization is accelerated. The distances between mycelial fragments is lessened, making the time to contact less than that which happen with grain spawn. Thus the window of vulnerability is closed to many of the diseases that eagerly await intrusion.

Before spawn is used, the receiving habitat is moistened to near saturation The spawn is then mixed thoroughly through the new habitat with your fingers or a rake. Once inoculated, the new bed is again watered. The bed can be covered with cardboard, shade cloth, scrap wood, or similar material to protect the mycelium from sun exposure and dehydration. After inoculation, the bed is ignored, save for an occasional inspection and watering once a week.

* In 1977, B. S toi 1er & J. Azzolini were awarded U.S. patent # 4027427 for this innovation.

and then only when deemed necessary.

Certain "mitations prevail in the expansion of mycelium and its ability for colonizing new substrates. The intensity or rate of inoculation is extremely important If the spawn is too dispersed into the substrate, the points of inoculation will be not be close enough to result in the rapid re-establishment of one, large, contiguous mycelial mat. My own experiences show that success is seen with an inoculation rate of 5-50%, with an ideal of 20%. In other words, if you gather a 5- gallon bucket of naturally occurring mycelium, 20 gallons of prepared substrate can be inoculated .Although this inoculation rate may seemhigh, rapid colonization is assured. A less intensive inoculation rate of 10% is often used by more skilled cultivators, whose methods have been refined through experience. Inoculation rates of 5% or less often result in "island" colonies of the implanted species interspersed amongst naturally occurring, wild mushrooms.

At a 20% inoculation rate, colonization can be complete in as short as one week and as long as eight. After a new mycelial mat has been fully established, the cultivator has the option of further expanding the colony by a factor of 5, or triggering the patch into fruiting. This usually means providing shade and frequent watering. Should prevailing weather condit'ons not be conducive to fruiting and yet are above freezing, then the patch can be further expanded. Should the cultivator not expect that further expansion would result in full colonization by the onset of winter, then no new raw material should be added, and mushrooms should be encouraged to form. At the time when mushrooms are forming, colonization of new organic debris declines or abates entirely. The energy of the mycelium is now channeled to fruitbody formation anddevelopment

Figure 16: Establishing an outdoor mushroom bed. Layer of moist mulch placed along edge of garden bed.

i o

\ '« r 0


Sprinkling spawn on top of mulch layer.

Sprinkling spawn on top of mulch layer.

Dehydrate Spawn Mushrooms

Adc'i.ig more moist mulch over the spawn layer.

Morel Mushroom Production
Figure 17. Healthy Stropharia rugoso-unnulata mycelium tenaciously gripping alder chips and sawdust Note rhizomornhs.

The mycelium of saprophytic mushrooms must move to remain healthy. When the mycelium reaches the borders of a geographically or nutritionally defined har:tat. a resting period ensues If not soon triggered into frui uing. over-incubation is likely, with the danger of Mie-back. " Only very cold temperatures wil! keep the patch viable for a prolonged period. Typically, die-back is seen as the drastic decline in vigor of the mycelium. Once the window of opportunity has passed for fruiting, the mushroom patch might be salvaged by the re-introduct'" n of more undecomposed organ" matter, or by violent disturbance. The mycelium soon becomes a site for contain^ation with secondary decomposers (weed fungi) and predators (insects) coming :nto play. It is far better to keep the mycelium running until fruitings can be triggered. Mushroom patches are, by definition, temporary communities.

King Stropharia lasts three to four years on a hardwood chip base. After the second year more material should be added. However, if the health of the patch has declined and new material is mixed in, then the mushroom patch may not recover to .ifs original state of ":gor. Mycelium that is healthy tends to be tenacious, holding the substrate particles together. This is especially true with Stropharia and Oyster mushrooms. (Hericium erinaceus and Morchella spp. are exceptions.) Over-incubation results in a weakened mycelial network which is i icapable of holding various substrate particles together. As mycelial integrity declines, other decomposers are activated. Often, when mixing in new material at this stage, weed fung' proliferate, to the decided disadvantage of the selected gourmet species. To the eye, the colony no longer looks like a continuous sheet

Oyster Mushroom Mycelium
Figure 18 From the same patch, three years later, the wood chips have decomposed into a rich soil-loam.

of mycelium, but becomes spotty in its growth pattern. Soon islands of mycelium become smaller and smaller as they retreat, eventually disappearing altogether. The only recourse is to begin anew, scraping away the now-darkened wood/soil, and replacing it with a new layer of wood chips and/or other organic debris.

Outdoor beds can be inoculated in early spring to early fall.The key to creating a mushroom bed is that the mycelium must have sufficient time to establish a substantial mycelial mat before the onset of inclement weather conditions. Spring time is generally the best time to inoculate, especially for creating large mushroom patches. As fall approaches, mushroom beds more modest in size should be established, with a correspondingly higher rate of inoculation. For most saprophytic species, at least four weeks are required to form the mycelial network with the critical mass necessary to survive the winter.

Most woodland species survive wintering temperatures. Woodland mushrooms have evolved protective mechanisms within their eel • lular network that allow them to tolerate temperature extremes. Surface frosts usually do not harm the terrestrially bound mushroom mycelium. As the mycelium decomposes organic matter, heat is released, which benefits subsurface mycelium. Mycelial colonization essentially stops when outdoor temperatures fall below freezing

Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

Get My Free Ebook


  • may
    What is spore slurry inoculation in mushroom growing?
    6 years ago
  • alexander eisenberg
    How do mushroom spores inocculate in the wild?
    6 years ago
  • Generoso
    How do i prepare dowel plugs for inoculation with spore?
    3 years ago
  • Kaden
    How to make a slurry from spore print?
    3 years ago

Post a comment