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Report 1 (of 5): Farming Fungus
- Germany
Introduction
In ancient Egyptian times, mushrooms
were considered a rare luxury. Today they are grown,
harvested and eaten worldwide for their taste and
nutritional value, including the benefits of low fat
content and essential vitamins and minerals. As a
result, interest in cultivating mushrooms (or edible
fungi) has grown. Mushroom production offers business
opportunities to those willing to develop a commercial
operation as an additional enterprise for the farm
or rural community, for farmers with limited amounts
of land, or for anyone interested in growing them
at home.
Shiitake mushrooms have been grown
in Japan for over 2000 years and are considered to
be among the tastiest mushrooms around. But Japan
is not the only mushroom loving country. In Hannover
in northern Germany, Nicola Krämer grows shiitake
mushrooms in her back garden and sells mushroom kits
through her website. A landscape architect
and environmental engineer by profession, Nicola is
spreading her passionate hobby for growing mushrooms
to other potential enthusiasts.
Mushrooms
All mushrooms belong to the fungi
family. Fungi differ from plants because, while most
fungi have plant-like cells, they miss the most important
feature of plants - chlorophyll. Chlorophyll enables
plants to produce food directly from carbon dioxide
and water using the sun's energy. Fungi therefore
grow only where there is organic material or a host
to feed off, in the process decomposing organic material
left behind by plants and animals. This plays an important
role in breaking down organic wastes such as cellulose
or lignin to make them available to other organisms
and plants. Many by-products from agricultural production
and food processing, for example, can be used as growing
material in mushroom production.
Mushrooms are popular with consumers
because they contain many essential amino acids and
so can be a valuable source of protein. Mushrooms
also provide vitamins B1, B2, C and minerals. Asian
traditions maintain that some speciality mushrooms
provide health benefits, including the shiitake mushroom.
Chinese doctors use at least 50 species and recent
scientific evidence suggests that many mushroom species
contain substances that may prevent or alleviate cancer,
heart disease or viral infections.
Mushroom Cultivation
In nature all groups of fungi (except
yeasts) grow in the form of thread-like structures
called hyphae. These together form a mass that can
be seen with the naked eye, called the mycelium, which
is the growing body of the fungus. After some time
the mycelium produces fruiting (the mushrooms you
eat), whose purpose is to grow the spores (the seeds
of the mushroom) that are necessary for reproduction.
Mushrooms can reproduce through spores,
or by breeding tissue extracted from a fruit-body
(similar to plant breeding through cuttings). In general,
cultivated mushrooms prefer to grow either on compost
or on woody material, depending on the type. The common
button mushroom prefers compost, while oyster, shiitake,
reishi and maitake mushrooms all grow on woody materials
such as sawdust, wood chips or logs, although sometimes
straw can be used.
Mushroom cultivation involves a number
of stages. These include:
- Choosing the type of mushroom to
be grown;
- Producing the culture or 'starter';
- Preparing the spawn;
- Preparing the compost or substrate;
- Spawning and incubation;
- Harvesting; and
- Post-harvest handling and marketing.
For beginners, a mushroom kit may
be the easiest way to start cultivating mushrooms
at home. These kits often consist of inoculated logs
or compressed sawdust blocks impregnated with mushroom
spores. Other kit types use inoculated wooden dowels
(plugs) or grain (wheat or rye).
Assessing the market
When considering growing any type
of mushroom commercially, some key questions need
to be answered first. These include:
- Is there a market for the product
and will it be possible to sell enough mushrooms
at a price above the cost of production?
- What resources are needed to be
successful, including skills, labour and time, sources
of information, assistance and credit, input suppliers,
processors and distributors?
- Will it be affordable and, in the
long term, profitable?
After this has been decided, questions
need to be asked about the market itself:
- What is the potential market size
for this product?
- How many competitors are there
for this market?
- What prices can sellers expect
to receive for a given level of quality?
- What trends are there in consumption,
competition, and pricing?
- What proportion or share of the
market can be captured?
Many mushroom growers sell their produce
commercially, even on a small scale. Although experienced
mushroom growers provide competition, small and efficient
producers who provide a good service, a quality product
and consistent supply are often able to compete in
price by building up local customers. In addition,
producing rare or special mushroom types such as Lions
Mane or Reishi can also help to establish a business.
Good knowledge of the market, the demand and the product
can be key to successfully selling mushrooms.
Possibilities include:
- Direct marketing of the fresh or
dried product (farmers' markets, gourmet chefs,
internet or mail order offerings);
- Value-added products (mushroom
sauces, dried entrée mixes, teas);
- Wholesale system set up for fresh
produce (contract or to wholesaler).
Although fresh mushrooms have a short
shelf-life (less than a week without refrigeration),
the fresh vegetable market is perhaps the most profitable.
However, shiitake dry easily and reconstitute very
well, so mushrooms of lower quality or freshness can
be dried, packaged and sold in retail and restaurant
markets, or by mail order.
Types of Mushroom
The choice of which species of edible
mushroom to grow depends largely upon the waste materials
available for use as a growing base, but also the
cost of equipment, level of skill required to manage
the life cycle of the fungus, and the established
market for that species. Based on these criteria,
oyster (Pleurotus ostreatus) and shiitake (Lentinus
edodes) mushrooms are best for most beginners.
They are relatively easy to grow and there is an increasing
market for them, thanks to the efforts of large commercial
producers of white button (Agaricus) mushrooms
who have diversified into other speciality mushrooms.
Shiitake mushrooms
The Shiitake mushroom is a wood-inhabiting
mushroom that grows best on beech or oak wood (although
alder or birch can be used). They are grown on logs
outside or can be produced inside on specially prepared
sawdust blocks. Shiitake growing has potential as
a low-cost enterprise because they can be cultivated
on a small scale with little initial investment and
there is much demand for the product on a commercial
basis.
An easy and fast way to grow shiitake
mushrooms is to use a mushroom culture. This is an
inoculated block of wood chips and sawdust mixed with
other organic materials. The blocks are manufactured
in a special process involving sterilisation and then
inoculation with spores. The mushroom culture can
be grown indoors or outdoors if protected from direct
sunlight. A high humidity is advantageous (you can
cover the culture with a plastic bag) and a temperature
of 14 to 18 ºC is ideal. Starting with mature cultures,
the mushrooms usually start to grow after a few days.
Cultures are normally exhausted after about 6 months,
by which time several mushroom harvests will have
been produced.
Another method, one of the oldest
ways of growing shiitake mushrooms, is to use logs,
which typically yield harvests over several years.
The logs can be seeded using inoculated wooden plugs
or can be bought already inoculated.
Growing Shiitake on Logs
Logs generally begin producing 12
to 15 months after inoculation. After this they usually
continue to fruit for 4 to 5 years producing up to
1 kilogram (1-2 pounds) per year or about 20 per cent
of the initial wood weight by the time the log is
fully consumed. Plugs are made in a laboratory using
sterile wood dowels, usually beech, which are then
inoculated with mushroom mycelium. After the plugs
have been inserted into holes in the logs, the mycelium
grows out into the surrounding wood.
In order to prepare the wood for plugging,
equipment is needed, including a drill, an 8 or 10
millimetre (about half an inch) drill bit, a hammer
and fresh deciduous wood logs (not coniferous), preferably
oak or beech. Drill 10 to 15 holes about 5 centimetres
(2 inches) deep, spread out over the whole surface
of the log. Then hammer the plugs into the holes.
A slightly larger hole can help if the wood is very
fresh or damp. However, the plugs should not be loose
in the holes and it is best if they are quite tight.
Since the mushroom mycelium is also contained within
the plugs it doesn't matter if mycelia on the outside
of the plugs fall off when they are inserted.
Logs can be inoculated at any time
of the year. However, they should be protected from
heavy frost, particularly during the first six weeks.
After inserting the plugs, it helps to seal the holes
and the cut ends of the logs with wax or latex to
protect against other fungi, insects and drying out.
Shiitake mushrooms are usually grown
logs 8 to 15 cm (3 to 6 inches) in diameter and up
to 1.2 metres (4 feet) long, but short thick logs
(50 cm or 20 inches long) can also be used. Approximately
50 plugs are suitable for four or five logs. It is
important to ensure that the logs have not dried out
and do not show signs of other fungi at the time of
inoculation. Logs should not be stored for longer
than three months after cutting, and the bark should
be left on as it protects the wood. The bark is more
durable for logs cut in winter, so this is the best
time to cut them.
Growth Phase
After inoculation some old logs or
strips of wood can be placed on the bare ground or
grass (not on stones or concrete) in a shady place
in the garden and the inoculated logs placed on top.
The logs should then be covered with straw to a thickness
of approximately 20cm (8 inches) and the whole pile
covered with plastic sheeting. It is important to
punch holes in the plastic sheeting to allow air to
circulate. The logs should stay in the heap for about
12 months. Care must be taken to protect the logs
from frost, especially during the first six weeks.
The storage temperature should not exceed 30°C as
higher temperatures can damage the mushrooms.
Alternatively you can initially store
the logs indoors, in a cellar for example, in order
to maintain a high humidity. The logs can be placed
in plastic sacks with air holes in them. In spring,
the logs can then be put out in the garden and can
be placed on bare soil in a shady area of the garden,
and watered to keep moist if necessary. During the
growing phase, an ideal place is below bushes or in
high grass under trees, as moisture evaporation creates
the ideal microclimate. In such conditions, coverage
with a plastic sheet is not absolutely necessary.
In longer dry periods, logs should be watered from
time to time using a watering can (once or twice each
week in very dry months).
Cut end of an oak log showing white shiitake mycelia
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After 9 to 12 months the mycelium should
be visible on the cut ends of the log. The growing phase
is then finished. However, the appearance of the mycelium
depends on the presence of enough moisture and they
may disappear again if the logs become too dry.
After the growing phase the logs are
frost resistant, but you should protect against extremely
heavy frost by covering them up (with straw, leaves
or cardboard).
Shiitake logs that have already finished
the growing phase can then be put indoors in the cellar
in late autumn. The warmth accelerates the growth
of the mushrooms. Since the logs must never be allowed
to dry out completely, they need to be occasionally
submerged in cold water for several hours.
All other mushroom types apart from
shiitake require direct contact with the soil. If
the logs are very long and thick you can cut them
after the growing phase into several small logs with
a length of 25 to 30 cm (10 to 12 inches). The logs
then need to be buried vertically in a shadowy, sheltered
part of the garden to up to a third of their length.
Maturing Phase
In order to accelerate mushroom growth
after the growing phase (after at least 12 months)
you can immerse the shiitake logs for about 24 hours
in cold water. Mushroom growth is accelerated by the
shock of the cold water and also by banging the cut
ends of each of the logs three to four times quite
hard on a stone or concrete surface.
Shiitake logs can be leant against
a fence or tree or wall so as not to obstruct the
mushrooms when they emerge, but they need to be protected
from snails. If the log is fully mature, the first
signs of mushrooms should appear 14 days after immersing
in cold water, and the mushrooms can be harvested
quite soon afterwards.
Harvesting
The first mushrooms usually grow close
to the holes where the plugs were inserted. Initially
only one or two mushrooms may appear, but the mushroom
grows throughout the log over a period of several
years. The logs only become fully used up when the
wood is rotten and starts to fall apart.
The mushroom should be harvested when
the skin below the cap has opened up and the gills
of the mushroom are visible, but the edge of the cap
is still slightly rolled inwards. Break or cut the
mushroom away from the log, leaving as little of the
mushroom stem attached to the log as possible. They
should be put immediately into cardboard boxes and
refrigerated. Refrigeration (ideally at between 2
- 4 ºC can extend the shelf life of shiitake from
four to five days to up to three weeks.
Shiitake ready for harvesting on beech log
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After harvesting, the shiitake logs
need to recuperate for six to eight weeks, during which
time mushrooms might start to appear again. Submerging
the logs in cold water will help to cause the mushroom
to start growing again after this period. This treatment
can be repeated every few weeks.
Drying can be accomplished by placing
the mushrooms over dry, warm air, preferably in sunlight,
which increases their vitamin D content.
Shiitake production based on information
from www.shiitake.de/eng
All images © Nicola Krämer
For further information, please contact:
Websites
http://www.fungi.com/
Fungi Perfecti is a family-owned, environmentally
friendly company specialising in using gourmet and
medicinal mushrooms to improve the health of the planet
and its people.
http://www.allaboutmushrooms.com/
http://www.mushroomadventures.com/
Sells all kinds of mushroom products
www.seedman.com/Rachel/Harvest.htm
Information on mushroom plug inoculation
attra.ncat.org/attra-pub/mushroom.html
attra.ncat.org/attra-pub/PDF/mushroom.pdf
Mushroom Cultivation and Marketing: Horticulture Production
Guide (html and pdf versions)
http://www.mykoweb.com/
Website dedicated to the study of the fungi or mycology
http://www.mycomasters.com/
http://www.zeri.org/
Shows examples of children growing oyster mushrooms
in Zimbabwe, coffee farmers growing shiitake mushrooms
on organic waste in Columbia and growing shiitake
mushrooms on brewery waste in Germany and Namibia.
http://www.pilzzucht-adelhorn.de/
Further Reading
Books from ITDG Publishing
Mushroom Cultivation
Peter Oei
£24.50, TOOL, 1996, ISBN: 9070857367
Covers cultivation techniques for developing countries,
the commercial potential of mushrooms, information
on how to perform a feasibility study, and technical
information on selection, growing and marketing.
Books from EarthPrint
Technical guidelines for mushroom
growing in the tropics
FAO
US$19.00, 1990, ISBN: 925103026X
Manual on mushroom cultivation
FAO
US$10, 1985, ISBN: 9251013241
This document is an output from
a project funded by the UK Department for International
Development (DFID) and the European Commission (EC)
for the benefit of developing countries. The views
expressed are not necessarily those of DFID or the
EC.
Acknowledgements
ITDG wishes to thank Nicola Krämer
for the information and images.
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