Read an Excerpt
CHAPTER 1
Getting to Know Mushrooms
People often ask me, "Why mushrooms?" They usually ask the question even more insistently when they find that I typically don't eat most of the mushrooms I grow or find in the wild. Until you get to know mushrooms, you may not realize the complexity of the mushroom world. Their world is one of endless fascination and intrigue. Mushrooms have innumerable uses and innumerable stories to tell.
Everyone knows that mushrooms can be used as food, but did you know that you can use mushrooms to make paper, paint, fabric, dyes, and hats? Did you know that there are mushrooms that glow in the dark? Are you aware that mushrooms are miniature chemical factories, and the toxins that fungi produce are used to make citric acid, birth control pills, and penicillin? Did you know that there are "zombie mushrooms" that can take over the brains of insects, force them to climb upward to the highest point possible in a tree, colonize their bodies, and grow a mushroom — all to release their spores? The more I learn about mushrooms, the more enthralled I become.
The Culture of Mushrooms
Mushrooms play many different roles in human life. One of those roles is as a cultivated crop, and that's the primary focus of this book. But as mushroom growers you should also know something about the other roles of mushrooms, because you'll certainly encounter them as you explore the intricate and diverse world of the mushroom.
Mushrooms for Food
When most people think of mushrooms, they're probably thinking of brown Portabellas or White Buttons, the common grocery store mushrooms that many of us enjoy on our salads or hamburgers.
White Buttons and Portabellas are species of the genus Agaricus. These are rarely grown on a small scale because their cultivation is dominated by the major mushroom farms, highly mechanized operations that mass produce mushrooms for low prices that small farms cannot hope to match. Agaricus species mushrooms are grown on a manure-based substrate that must be composted before it can be inoculated. This process can take from weeks to a month or more. After the composting process, the fungi are introduced to the growing area.
Agaricus species mushrooms are referred to as secondary decomposers because of the two-stage decomposition process that must occur before the mushrooms fruit and are harvested. The time-consuming preparation of large amounts of compost, combined with the low market price, make White Button and Portabella mushrooms low-priority species for most small growers.
Most of the mushrooms grown by hobbyists and small-scale cultivators are primary decomposers. Primary decomposers perform the first round of decomposition of a substrate, which is often a wood-based medium. They are the first (primary) organisms that begin to break down the cellular structure of the wood on which they are being grown. Unlike secondary decomposers, such as Agaricus species mushrooms, primary decomposers don't require an extended composting process to prepare the substrate.
Most of the "gourmet" mushrooms that cultivators are interested in, such as Shiitake and Oyster, are primary decomposers that break down their substrates in order to grow. Organisms like these are known as saprophytes. Saprophytes decompose organic material, such as the cellulose and lignin in wood or other plant material, to gain the energy they need for their biological processes. Some of the most common substrates for gourmet mushrooms are sawdust, woodchips, and straw.
Many of the most popular types of edible mushrooms, such as Morels and Chanterelles, cannot be grown by humans, so people hunt them. These types of mushrooms are called mycorrhizal fungi (myco = fungi, rhiza = roots). Neither primary nor secondary decomposers, mycorrhizal fungi get their energy through symbiosis with trees and certain plants. The fungus increases the surface area of the roots of its host tree by several orders of magnitude, scavenging the soil for water and nutrients that were previously inaccessible to the tree. In return, the tree provides the fungus with carbon in the form of sugars generated through photosynthesis in the leaves. More than 90 percent of all land plants form a mycorrhizal symbiotic relationship with fungi.
We have not yet been able to replicate this complex biological interaction in the laboratory for most species, so none of these common wild mycorrhizal mushrooms can be grown under controlled conditions. Some of the most popular edible mycorrhizal species are outlined in the table shown here.
Common Edible Mycorrhizal Mushrooms
King Bolete Boletus edulis
Mushrooms for Fun
Collecting mushrooms for the dinner table is only one of many reasons to hunt mushrooms in the wild. Many people hunt them for the same reasons that others go birding or enjoy a hike in the woods. The ability to identify mushrooms in the wild is a rare talent and a way for people to connect with an important but rather mysterious part of nature.
Many states have local mushroom clubs where people can meet and take mushroom walks in the woods, learning the key characteristics used for identifying mushrooms. Organized gatherings of mushroom hunters are often referred to as "forays." The North American Mycological Association (NAMA) is the umbrella organization for all of the local mushroom clubs in the United States and Canada.
NAMA even formed a committee to help amateurs cultivate mushrooms as a hobby and for profit. There is an online forum at the NAMA website for cultivators, and the committee puts on cultivation events at the yearly NAMA foray. Several local mushroom clubs also have committees and events that are specifically related to mushroom cultivation.
Even if your interests are primarily cultivation, I encourage you to hike in the woods, collect wild mushroom species, and work to identify them. This is particularly easy if you have a mushroom club near your home, with professionals available to advise you, but it's entirely possible to learn the major mushroom species in your area on your own. Most regions of the country have regional field guides available that serve as a great starting point when learning to identify mushrooms. Observing and collecting mushrooms in the wild will enhance your abilities as a well-rounded cultivator: you'll notice the mushrooms' natural environments, their growth patterns, and their ecological associations. Aside from that, it's great exercise with a built-in learning component!
Mushrooms for Health
Every year, scientists, doctors, nutritionists, and the public learn more about the medicinal benefits offered by many varieties of mushrooms. Even some of the most commonly cultivated mushrooms (e.g., Shiitake, Maitake, and Lion's Mane) have been shown to be effective in fighting many different ailments.
Reishi, also known as the "Mushroom of Immortality," can be found in the wild throughout much of the world. It has been used medicinally in China for thousands of years, and scientific research shows that Reishi could have very real health impacts in Western societies as well. One of its primary biological benefits is its enhancement of immune system response. It has also been shown to help with stress, blood pressure, blood sugar levels, and cholesterol. And it's a mushroom that can be grown effectively at home, indoors or out.
Mushrooms as Hallucinogens
No conversation about growing mushrooms is complete without a discussion of the role of active mushrooms in our society. Active mushrooms are mushrooms that contain hallucinogenic compounds such as psilocybin. Although illegal in most states, it's hard to deny that active mushrooms are a significant part of mushroom culture, and the hallucinogenic properties pique many people's interest when they consider mushroom cultivation.
When I mention mushrooms, most people joke about one of two subjects — either that mushrooms will kill you, or that they'll make you hallucinate. While there are surely mushrooms that can do both, the vast majority of mushrooms do not belong in either category. And although the vast majority of mushroom cultivation methods are the same no matter what species you choose, this book is not a guide to the cultivation of species that contain psilocybin. The focus of this book is on nonactive edible species that are grown as a source of food.
If you're looking for more information about active species, and you're in a place where their cultivation is legal, I point you to the online mushroom forums in Resources.
Mushrooms as a Business
As a result of the continuing rise of the sustainability movement, the local foods movement, and the desire for a healthy lifestyle, mushrooms are now a product with a ready market. Specialty mushrooms, once sold only in gourmet and health food stores, are now available in most major grocery stores. This means that there's potential for mushrooms to be grown as a commercial commodity in almost every region of the country. And because mushrooms have a very short shelf life, grocers and restaurants are always looking for local sources rather than having them shipped from long distances.
All the skills presented in this book should be viewed as prerequisites for anyone contemplating commercial mushroom production. Most of the commercial growers I know started on a small scale in their own homes using these same methods. Once you've mastered these methods, you should have the knowledge base to easily expand to sales at the commercial level.
Mushrooms in Research
Mycology is the field of mushroom science. Mycology means, literally, "the study of fungi," and its breadth encompasses all of the mushroom world, not to mention countless molds, rusts, and other fungi. An estimated 1.5 million species of fungi are thought to exist, of which only 10 percent are known to science. There are many left to discover, but there are very few mycologists in the United States or around the world, which means there's every possibility for a passionate researcher to make a mark in the field.
If you're an ecologist, you could consider researching why we can't grow mycorrhizal mushrooms. If you're involved in biochemistry, medicine, or industry, you probably already understand that mushrooms produce thousands of compounds that could benefit human health and civilization. Isolating or synthesizing just one of these unknown compounds could have important beneficial effects.
The Cultivation Process
No matter what species of mushroom you want to cultivate, the life cycles will be essentially the same, so you'll follow the same basic set of procedures.
Spore Germination
Mushrooms reproduce by forming spores. Spores germinate when they come in contact with a substrate that has the right mixture of nutrients, moisture, and temperature. When they land on a suitable substrate, they begin to germinate and produce new cells that extend outward, forming filamentous structures called hyphae. Each viable spore that encounters the right surface will send out its own hyphae, and when two compatible types of hyphae encounter each other, they join up and exchange genetic material. At this point, the rate of hyphal growth increases, and a large, interwoven mass of hyphae, called mycelium, is formed. Expanding this mass of mushroom mycelium, while keeping it uncontaminated, is the primary goal of any cultivator.
Mycelium Growth
The more mycelium you can reliably produce, the more mushrooms you'll be able to grow. Using an analogy from the plant world, think of growing mycelium as the vegetative phase of the growth cycle. During this phase, the mycelium is trying to colonize and decompose any material that it can. It's exuding enzymes (which promote decomposition) onto the surface of the substrate, and the nutrients that are made available are absorbed back into the mycelial network. This mycelial network will continue to expand until it runs out of a fresh nutrient source to colonize or until it encounters another competitive organism, such as a contaminant in the culture.
For cultivation, the mycelium is usually grown on a grain-based substrate in canning jars during the vegetative phase. Some common examples of substrates include a brown rice flour–vermiculite mixture in half-pint canning jars, or hydrated rye grain in quart canning jars. Any substrate must be sterilized using a pressure cooker before it's inoculated with mycelium. This kills off competitive organisms that may contaminate your culture and inhibit further growth.
Increasing the Mycelium
To keep increasing the size of the mycelial mass, mycelial networks can be transferred from one colonization vessel to another larger one. For example, you could inoculate a small jar of grain with an initial culture and allow that jar to become fully colonized. You could then break up that colony and transfer it to six or seven fresh jars of grain under sterile conditions. You'd allow each of these freshly transferred jars to colonize as well. Finally, the contents of each of these jars could be transferred to a spawn bag containing 5 pounds (2.3 kg) of grain. In the end, you'll have turned 2 cc of spore fluid or liquid culture into 35 pounds (16 kg) of grain spawn, capable of producing many pounds of mushrooms.
Transferring Mycelium to a Fruiting Substrate
Before mushrooms can begin to form, the spawn must be transferred to its fruiting substrate. Beginners growing small amounts of mushrooms often inoculate the fruiting substrate directly, so no transfer is necessary. This greatly reduces the chance of contamination. For growing larger amounts of many common edible mushrooms, like Shiitake and Maitake, this fruiting substrate is wood based, so you must transfer your colonized mycelium to a bag of sterilized sawdust supplemented with wheat bran. For Oyster mushrooms, straw is the most common fruiting substrate.
Fruiting
The final phase is the fruiting phase, when the mushrooms actually begin to form. Once you have successfully colonized the amount of mycelium you need, you'll want mushrooms to begin to form on your fruiting substrate. You accomplish this by creating the right environmental conditions for fruiting, which typically involves adding light, increasing the humidity, and decreasing the temperature and the levels of carbon dioxide (CO) by introducing fresh air. This set of actions will cause primordia (small, immature mushrooms) to appear on the surface of the mycelium. Once primordia begin to appear, the substrate is said to be pinning, or beginning to grow actual mushroom fruitbodies. Primordia can become fully grown mushrooms, but at this point, the process is in its most fragile state, and special care must be taken to maintain consistent environmental conditions. This is the only way to ensure that the mushrooms form properly.
Common Cultivated Species
When selecting a species of mushroom to cultivate, it's best to start with one of these commonly cultivated species of saprophytic mushrooms. Cultures of these fungi, available from online stores or culture banks, have generally been selected for their ease of cultivation and high yields.
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Excerpted from "The Essential Guide To Cultivating Mushrooms"
by .
Copyright © 2014 Stephen Russell.
Excerpted by permission of Storey Publishing.
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