Commercial Cultivation of Exotic Mushrooms
Mushrooms
are cultivated and consumed worldwide for both culinary and medicinal purposes.
The commercial potential of an edible species for any grower depends on a
number of factors including edibility and shelf life, local and regional
culinary customs, the existence of a distribution network, among others. Some
edible species are cultivated and consumed internationally while other edibles
have not yet achieved worldwide culinary appeal and are therefore cultivated
only in countries where a local market has developed. There are a few species
that are cultivated strictly for their medicinal properties while a few are
cultivated because they are good edibles and also have medicinal properties. The
following species are currently cultivated on a commercial scale for specific
marketing areas.
Common
name (Latin name)
Main cultivation area
Edible
Species:
White
or Brown Button mushroom (Agaricus spp.)
Worldwide
Shiitake
(Lentinula edodes)
Worldwide
Oyster
or Abalone (Pleurotus ostreatus) Worldwide
Paddy
Straw (Volvaria volvacea)
Asia
Enokitake
(Flammulina velutipes)
Japan, Taiwan, China, N. America
Maitake
(Grifola frondosa) Japan,
North America
Nameko
(Pholiota nameko) Japan
Wine-red
Stropharia (Stropharia rugoso-annulata)
Europe
Blewit
mushroom (Lepista nuda) Europe
Shiimeji
(Lyophyllum descastes)
Japan, N. America
Kuritake
(Naemataloma sublaterium))
Japan
Kukirage
or Wood-ear fungus (Auricula auricularia) Asia
White
Jelly fungus (Tremella fugiformis) China
Medicinal
Species:
Reishi
or Ling Zhi (Ganoderma lucidum)
China, Japan, Korea
Caterpillar
Fungus (Cordyceps sinense)
China
Mycological Information
Mushrooms are the reproductive bodies formed by certain fungi. Just like
the apple on a tree, mushrooms are the "fruits" of these fungi. The
actual organism that produces the mushrooms is called MYCELIUM,
a strand like mass of white cells found in the growing substrate which
may be a dead tree stump, a live tree, or organic material in the soil.
Fungi reproduction depends on the existence of specific environmental
conditions, especially the moisture or humidity level, the temperature, and the
availability of nutrients. Optimum conditions vary among species.
Under the right conditions “fruiting” occurs and the mycelium
produces mushrooms. When mature,
the mushrooms release millions of spores into the environment for further
propagation of the species.
Mushrooms are classified
into three types according to their growing characteristics.
Parasitic mushrooms attack a living host plant, usually a tree, and eventually
kill it. They may also be found growing on dead trees, but they probably started
growing while the tree was alive and contributed to its demise.
An example of a parasitic mushroom is the
Honey mushroom (Armillaria mellea).This type of mushroom can be cultivated but will
require a living host. Some parasitic mushrooms also function as saprophytes
(described below).
Mycorrhizal mushrooms form a symbiotic (mutually beneficial) relationship with the
roots of trees or bushes. In fact, the root tips of all plants are coated with a
fungus which breaks down the organic matter in the soil and makes it available
to the plant. The plant in turn produces sugars and exchanges these with the
fungus. Some of these symbiotic fungi produce mushrooms.
Examples include the Boletes, Truffles, Chanterelles, and Amanitas.
Cultivation of this type of mushroom requires the other half of the symbiotic
relationship which is the live tree. It is almost impossible to establish this
symbiotic relationship under controlled conditions on a commercial basis.
However, success has been achieved with truffles whereby a grower inoculated the
roots of small oaks with the mycelium, planted them, and then waited for more
than ten years before harvesting the truffles.
Saprophytic mushrooms live on dead organic matter such as dead trees, stumps, old
roots, grass, straw, compost, etc. Mushrooms in this group are those that are
successfully cultivated including Shiitake, Oyster, Champignons or White Button
mushrooms (Agaricus spp.), Portobello, Enokitake,
Reishi, Maitake, Paddy Straw mushroom, and many others.
All of these types of mushrooms play roles in ecosystems throughout the
world. One of the key roles that mushrooms play in natural systems is the
decomposition of dead organic matter. Decomposition is accomplished by a
succession of saprophytic fungi (the following examples are edible species but I
am sure there are many other). The primary decomposers such as Shiitake, Oyster,
and Wine Cap mushroom (Stropharia
rugoso-annulata), start the process by breaking down the lignin and
cellulose in wood, straw and other plant matter. Secondary decomposers take over after the substrate has been
partially broken down. Secondary decomposers typically grow on compost and
include the White Button mushrooms and Portobello (Agaricus spp.). Tertiary
decomposers are typically soil dwellers existing in reduced substrates.
These include some Agaricus species, the Orange Peel mushroom, Conocybe,
Agrocybe, and Pluteus.
Each mushroom has specific growing parameters (light, moisture,
temperature) which must be fulfilled for successful cultivation and these
precise conditions can be quite difficult to reproduce.
For example, the growth stimuli that morels require for reproduction are
so complex that cultivating them indoors in controlled conditions is a hit or
miss procedure at best. They can be cultivated outdoors by preparing a site
suitable to their growth and introducing
the morel mycelium in form of spawn (mycelial
culture grown out on grain or sawdust). On the other hand,
Oyster, Shiitake, Shaggy Manes and others depend on a less complicated interplay
of stimuli in order to reproduce and have an almost 100% success rate if
instructions for cultivation are followed carefully.
Many of the above-mentioned mushrooms are edible and some can be easily
cultivated using the techniques described below. Primary and secondary
decomposers are the most suitable for cultivation since the mycelium of these
species is usually quite vigorous and with proper techniques there is a high
rate of success. In addition, substrates are readily available. The by-products
from agricultural processes and the lumber industry are suitable substrates for
mushroom cultivation and include hardwood logs for outdoor Shiitake cultivation,
sawdust for indoor cultivation of many species, and grain straw for Oyster
cultivation.
Cultivation Techniques
Many
mushrooms species can be cultivated at home on a small scale using
various methods. Since home
cultivation is mainly a hobby, the expectations of the grower and the results of
cultivation can vary widely. However, the
experimentation alone can lead to a satisfactory experience.
Commercial
cultivation, on the other hand, requires reproducible, quantitative results. A
steady supply of mushrooms is necessary in order to enable the commercial grower
to satisfy the demands of potential
customers such as food distributors, supermarkets and restaurants. Since
commercial cultivation usually involves a substantial investment, the
cultivation techniques must be dependable with consistent results so that a
marketing strategy can be formulated and a reasonable return on the investment
realized. Successful commercial cultivation techniques have been determined for
a number of edible and medicinal mushroom species which have a high potential
for commercial production.
These
techniques fall into three categories:
·
Indoor
cultivation on sawdust, straw, compost, or other suitable substrates
·
Outdoor cultivation on hardwood logs
·
Outdoor
cultivation in beds of straw, wood chips or other suitable materials
Indoor Cultivation
Many mushroom species are cultivated indoors
in climate-controlled buildings. Certain species require adherence to strict
parameters for successful cultivation, others are more forgiving. The buildings
necessary for indoor cultivation can therefore vary in sophistication and cost
depending on the species of mushroom that is cultivated. Substantial investment
will likely be required for cultivation of sensitive species such as Maitake or
Enoki, where temperature control and humidity are critical. Others, such as
Oysters, can prosper in insulated greenhouses with less sophisticated controls.
Indoor
tray cultivation
The Agaricus species, which includes the
common White Button mushroom, is the most widely cultivated species of
mushroom using this technique. There are two commonly-cultivated species
-- Agaricus
bisporus and Agaricus bitorquis.
There are also various strains of these species which exhibit different
characteristics such as the colour range which varies
from pure white to light brown. The
substrate for this species normally consists of animal manners and cereal straw
which have been well composted, meaning that high temperatures were achieved
during the composting process. The elevated temperature is necessary in order to
kill the many fungal competitors present in the original substrates. The compost
is then placed in long trays in a climate-controlled building and inoculated
with spawn of the desired strain. The trays are kept in the dark
while the mycelium from the spawn runs through the compost. At the
appropriate stage the substrate is “cased”, which means covered to a depth
of about 3 to 5 cm with casing soil that is in general a mix of peat moss and
limestone. The casing protects the colonized substrate from drying out and
provides a stimulus for the mushrooms to form. After approximately two weeks of
casing, the mushrooms start forming and are picked continuously until the
nutrients in the compost are used up. These mushrooms have been traditionally
picked at a fairly young stage, hence the name “button”.
A recent development in North America has been
to allow these mushrooms to fully develop to maturity. At this stage they may
reach 3 to 6 inches across the cap. They are sold as Portobello or Portabella
mushrooms, and have become very popular.
Tray cultivation has been used with varying
degrees of success for the production of Oyster and Shiitake mushrooms using
pasteurized straw and sawdust respectively. Paddy Straw mushrooms are also
produced on trays in temperate zones, whereas they are normally cultivated in
outdoor beds in tropical climates.
Indoor
bag or bottle cultivation
Bag cultivation is used worldwide to grow Shiitake, Oyster, Shiimeji, and Maitake.
Substrates suitable for this method range from hardwood sawdust, aged softwood
sawdust, wood chips, cereal grain straw, corn cobs, various types of hay, and
sugar cane bagasse to name a few. The above materials are supplemented for
nitrogen with such ingredients as bran from rice, wheat, spelt and other grains,
cornmeal, cottonseed meal and many more at a ratio of approximately 1 to 4.
Other additives may include sugar, molasses, gypsum, limestone etc.
The ingredients are mixed together dry, then
water is added to obtain a 60 to 70% moisture content level. The wet mix is then
bagged in autoclavable bags such as high density polypropylene or polyethylene.
The bags are then sterilized by steam in an autoclave or retort for 1 to 4 hours
at 15 pounds per square inch (psi) or 1.1 kg/cm2.
Alternatively, atmospheric pressure steam sterilization can be done for
12 to 18 hours. This has the effect of destroying competitor fungi or bacteria
which may be present in the substrate. However, for certain species such as the
Oyster mushroom, pasteurization rather than sterilization of the substrate is
sufficient since this particular mycelium can tolerate or even benefit from some
bacterial action.
Following sterilization protocols, the bags
are inoculated with the “spawn” (mycelial culture grown out on grain or
sawdust) of the desired species in a very clean or sterile environment. The bags
are sealed but some form of gas exchange must be provided, either via a
breathable patch on a specially-made bag or simply by closing the bag around
a wad of cotton. The mycelium will run through the substrate in a few
weeks, binding the mix together into a solid block. The bags are then moved to a
grow room which has a high humidity level -- approximately 80 to 90%.
In order to initiate “fruiting” (mushroom
production; also referred to as “flushing”), the plastic bag
is removed for Shiitake or simply perforated for Oyster mushrooms. Within
a few days the mushrooms begin to form on the blocks, or through the holes in
the bag. The mushrooms will be ready to pick within days or weeks depending on
the species. After picking, the blocks should be left to rest for a period of
time after which they can be soaked in water to initiate a second fruiting, or
flush. Three to four flushes are possible with Shiitake. Other species may only
have one flush. Typically the nutrients in the blocks are used up within a
couple of months. Mushroom yields
vary from 30 to 50% of the original weight of the substrate. A variation of this method is
the use of autoclavable bottles instead of bags. This method is used
extensively for Enokitake, Shiimeji, and Hiratake mushrooms. Specialized
equipment for mixing, filling and inoculating bags or bottles, and for emptying
bottles, is available, mainly from Japan.
Many growers who are not prepared to set up
sterilization and laboratory facilities can purchase bags or bottles already
grown out on substrate and ready to fruit. All they have to do is provide
suitable conditions in growing
rooms or outdoor areas and carry out the final stage of the process, which is
fruiting and harvesting. There are suppliers of ready-to-fruit bags or bottles
in North America, Europe and Asia.
Set-up costs for a cultivation enterprise vary
widely depending on factors such as the geographical location (due to the
heating and/or cooling of buildings), desired species,
whether a laboratory and sterilization facility is required, availability
of ready-to-fruit substrates, and the degree of sophistication of grow-out
areas, among others. The first step in setting up a mushroom-growing enterprise
is to carry out a survey of the mushroom species that can successfully be
marketed in a given geographical region. This
is a must since the species chosen will, to a very great extent, determine the
setup that will be required.
Outdoor
Natural Log Cultivation
Commercial cultivation on hardwood logs such
as Oak, Ironwood, Hickory and others consists of inoculating logs
from the limb wood of freshly cut
trees (preferably winter cut) with mycelium of the desired mushroom species.
Softwood logs are not suitable because of the inhibiting substances in their
resin. The best time to cut the trees is just as the leaves finish turning
colour. This is the point of highest concentration of sugars and vitamins in the
wood. The next best is anytime during freeze-up. The logs should be left in long
lengths in the bush until spring, at this point they can be cut in lengths of
3-4 ft. The mycelium is introduced in the form of spawn, a blend of sawdust and
nutrients with the mycelial culture growing through it, or wooden dowel plugs
which have been impregnated with the mycelium. Suitable size logs vary from 7cm
to 20cm in diameter and from 1m to
1.3 m in length. Oak is the preferred species
for a commercial operation because it gives consistent results.
Inoculation involves drilling a series of holes into the logs (average 50 holes
per log) and introducing the spawn into the holes
The holes are then filled with either dowel plug spawn or sawdust spawn,
sawdust spawn works faster than plugs. Plugs can be placed in the holes by hand
and tapped in with a hammer, sawdust spawn requires an applicator. The holes are
then sealed with molten wax. The wax prevents the spawn from drying out and
dying. A newer method is sawdust
plug spawn with a styrofoam backing. The plugs are inserted manually into the
pre-drilled holes , no wax is necessary as the styrofoam acts as a vapour an
contamination barrier. Sophisticated
machines that insert the spawn into the pre-drilled holes and seal them with a
piece of styrofoam in a single step are available. These machines are expensive
but for a large commercial operator who is inoculating thousands of logs, the
machines can save on labor costs.
Following inoculation the logs are stacked
outdoors under a natural or
artificial canopy that provides from 65 to 85 % shade. These logs are monitored
for moisture content (by weighing pre-selected logs), and are watered as necessary. The mycelium takes off from the
spawn and runs through the logs, starting in the sapwood. Depending on climatic
conditions and strains used, mushrooms will start to fruit out on the logs after
6 to 18 months.
When the logs start producing they are stood
up in rows between posts or trees.
This arrangement facilitates picking and keeps the mushrooms away from
dirt and insects. The logs will produce
mushrooms for an average of five years without further inoculation, as long as
the mycelium is kept alive. A consistent mushroom production schedule is
achieved by watering or soaking the logs in tanks. The water stimulates the
mycelium in the log to fruit, producing mushrooms a few weeks later. The logs
are then allowed to rest for 6 to 8 weeks and the soaking is repeated. A daily
watering schedule will eventually produce a consistent flushing of mushrooms. A
dependable delivery schedule can then be set up for marketing.
Log Management
More recent developments in log cultivation
techniques make use of shaded greenhouses to house the logs. Humidity can be
controlled much better, inoculations can start sooner, and fruiting seasons can
be extended.
The methods described above is used for
Shiitake cultivation worldwide where a consistent supply of Oak logs is
available. Outdoor and indoor cultivation make Shiitake the second most
cultivated species after the White Button mushroom in terms of quantity of
mushrooms produced. Outdoor cultivation is dependable, with a 90% success rates
for logs. A top-quality product is
produced from this method, which, if
not sold fresh, can be dried to top grade dried mushrooms. The same technique
can be used for Wood-ear, Nameko, Kuritake, Tremella,
Maitake, and Reishi. Variations in log management include partially
burying the logs in the ground in the bush or under artificial shade and having
the mushrooms pop up from the ground. This is done for Nameko and Reishi.
Depending on your location and availability of
logs outdoor cultivation can be the method requiring the least investment for
startup. If a woodlot is available
as a growing area, no artificial shade is required. If you can cut your own logs
a major cost is eliminated. Typical startup costs for a Shiitake mushroom
operation in Southern Ontario for a person who has the woodlot but must purchase
Oak logs are as follows:
·
logs
at CDN$ 150.00 per bush cord plus delivery translates to approximately $ 2.00
per log;
· spawn at $ 1.00
to $ 3.00 per log, depending on quantity
·
drills and drill bits can add
$ .50 - $ 1.00 per log;
·
labor
costs for inoculation - $ 1.00 per log;
·
The
total is approximately $ 5.00 to $7.00 per inoculated log.
The lifespan of a log (with a single
inoculation) averages 5 years. With proper management the mushroom production
can be at least ½ kg. per log per
year. If you use shaded polyhouses and "force" the logs you can get up to 4 lbs.
per log per year but for a shorter lifespan. In total you can expect approx.
3 kgs. or 6 - 8 lbs. from each log.
Outdoor
Sawdust Substrate 'Log' Cultivation
A variation on the natural log cultivation
method is the use of logs made up from substrates such as those described in the
indoor bag cultivation section. This technique is used extensively in China for
the production of Shiitake mushrooms. Once the blocks have been fully colonized
with mycelium and have matured, they are placed outdoor in partially buried grow
houses and fruited. This technique is only suitable for certain areas with the
right climatic conditions such as high humidity and temperature.
Outdoor
Bed or Mound Cultivation
This method is suitable for species that
require an outdoor stimulus to produce mushrooms and involves the preparation of
outdoor trenches or mounds located in a shady area. Substrates such as wetted
straw, sawdust, wood chips and compost are used. The substrates are sequentially
layered in the trenches or mounds with spawn added between layers. A final layer
of soil is placed on top. These beds or mounds are then thoroughly watered and
are then covered with cardboard or plastic until the mycelium has run through
the substrate. At this point the cover is removed and mushrooms will start to
come out. Species that are cultivated using this method include Paddy Straw
mushrooms in warm Southeast Asian countries and Blewit and Stropharia in Europe.
Marketing
Thorough research into the markets available
for your product is a must before any investments are made. Marketing requires
the investigation and consideration of a number of factors which will likely be
peculiar to any geographic location. The sale of the fresh mushrooms locally is
the most desired venue as processing and delivery costs can be kept to a
minimum. Potential customers include food distributors who supply restaurants,
wholesale vegetable distributors at local wholesale food terminals, supermarket
chains, restaurants, gourmet food retailers, and farmer’s markets. If you are
considering a large operation, distributors and chains are your best bet as they
already have a distribution network set up. Careful attention must be given to
pricing and profit margins. The
price structure for sales to a distributor or large chain would be lower than
for direct sales to restaurants or retailers, but the volume would likely be
higher. These kinds of marketing
decisions will impact both profitability as well as the level of production
required (i.e., labor costs will be higher). For smaller operations,
establishing a relationship directly with some upscale restaurants and retailers
or attending farmer’s markets may prove successful. Your personal attention to
these groups will be rewarded with a higher price for your mushrooms.
Markets for a quality fresh product may be
found in wholesale food distribution centers of major cities. Demand for exotic
mushrooms is usually higher in larger urbanized areas with access to a market
that is willing to pay the extra costs for high quality mushrooms. As of 2008
farmers markets are becoming popular due to the "shop local" movement and
may provide opportunities to market directly to customers and realize full
retail price. Adding mushrooms to a current line of market products will
enhance your bottom line.
A number of mushrooms can be marketed in a
dried, pre-packaged format. Shiitake
is one such mushroom. Large
quantities of dried Shiitake are brokered through Japan which is one of the
largest producers, importers and exporters of dried Shiitake in the world. Their
grading system is very strict and access to this market is extremely difficult.
Local markets for dried mushrooms are likely to prove more successful. A
potential vast market is in the production of value-added products using dried
mushrooms. Attending food trade fairs can be useful in determining which
products to produce and for contacting potential customers.
Government agencies may be available to
provide assistance in promoting your product. Contact your state or provincial
department or ministry of agriculture as well as government economic development
agencies.
Steps
to Commercial Cultivation
Anyone seriously considering setting up a
mushroom-growing enterprise should research a number of areas before making
decisions and/or investments:
·
Investigate
markets and distribution networks. Check the competition and prices for the
products at the wholesale and
retail levels.
·
Cultivation
techniques must be researched in depth. Pay careful attention to timelines.
A number of excellent books that describe these processes in detail are
listed in our catalogue.
·
Decide
on which species to grow that can be marketed successfully.
·
Investigate
sources and costs of the raw materials necessary for the species desired.
·
Financial
considerations: Assess costs of facilities,
labour and general operating costs. Correlate price structure to anticipated
production levels in order to determine return on investment.
·
Consult
expert opinion if available and request help from sources such as government
agencies.
Fun
Guy Farm is a supplier to commercial growers and hobby growers. We supply: books
to assist your research needs; grain spawn of various species for inoculating
bags, bottles, or outdoor “beds” of substrate; sawdust spawn, and sawdust
plug spawn of various species for log inoculation. We also produce
ready-to-fruit bag culture sawdust blocks as kits for home cultivation.
For commercial growers we supply, on a contract basis, large quantities
of spawn, ready-to-fruit substrates, and inoculated logs. We also supply
equipment such as drills and bits, and can broker large specialized equipment
purchases (such as dryers, slicers, mixers, bag and bottle filling machines
etc.). We can also provide consulting services tailored to the individual needs
of prospective commercial growers on a fee basis.
In particular, we offer consulting for the design of cultivation
facilities, selection of the most suitable mushroom strains, and training of
personnel at our facility. Our expertise can help to avoid costly mistakes in
setting up a commercial production enterprise.
For More Information Contact:
Mycosource Inc.
R.R. 1, Goodwood ON, Canada L0C 1A0
Tel: 416-402-9755
FAX: 416-963-5520
Internet: office@mycosource.com
