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Agrodok 40

Small-scale mushroom cultivation oyster, shiitake and wood ear mushrooms

Peter Oei with contributions by Bram van Nieuwenhuijzen


Š 2005 Agromisa Foundation and CTA All rights reserved. No part of this book may be reproduced in any form, by print, photocopy, microfilm or any other means, without written permission from the publisher. First edition: 2005 Authors: Peter Oei, with contributions by Bram van Nieuwenhuijzen Editor: Janna de Feijter Illustrators: Barbera Oranje, Mamadi B. Jabbi Design: Eva Kok Translation: Ninette de Zylva Printed by: Digigrafi, Wageningen, The Netherlands ISBN Agromisa: 90-8573-038-4 ISBN CTA: 92-9081-303-2


Foreword Mushroom cultivation fits in very well with sustainable farming and has several advantages: ? It uses agricultural waste products ? A high production per surface area can be obtained ? After picking, the spent substrate is still a good soil conditioner This Agrodok contains detailed information on how to grow three kinds of mushrooms: oyster, shiitake and wood ear mushrooms. These mushrooms are rather easy to grow on a small scale. Cultivation of the common white button mushroom and of the rice straw mushroom is very different and will therefore be dealt with in another Agrodok. Much of the information presented here is from my book “Mushroom cultivation and appropriate technologies for commercial mushroom growers”. By concentrating on three mushroom species only and on relatively simple technologies, I hope readers can obtain a sustainable profit from mushroom growing. Bram van Nieuwenhuijzen was the director of the Mushroom Growers’ Training Centre (nowadays known as C Point) at Horst, The Netherlands, for a number of years. He is currently involved in mushroom cultivation projects in several countries as an adviser through PUM Netherlands Senior Experts in The Hague. Peter Oei Chairman ECO Consult Foundation and Visiting Professor Fujian Agricultural University

Foreword

3


Contents 1

Introduction

2 2.1 2.2 2.3 2.4

Biology of mushrooms Fungi Fungus ecology Life cycle of fungi Temperature ranges of cultivated mushrooms

8 8 8 9 12

3 3.1 3.2

Mushroom farms Farm layout Farm hygiene

14 14 17

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Spawn production The starter culture The sterilisation process Clean environments Cultures Preparation of media Preparation of slants Mother spawn Preparation of the final spawn

18 20 20 22 24 27 28 32 34

5

Growing oyster mushrooms on pasteurised or ‘sterilised’ substrates Preparation of the substrate Heat treatments Spawning pasteurized substrate Spawning sterilised bags Spawn run Fruiting/cropping Harvesting Case description: Ahmedabad, India Case description: Bogor, Indonesia

37 37 40 44 44 47 48 50 51 54

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9

4

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5.10 Juncao Technology turns grass into mushrooms

56

6 6.1 6.2 6.3 6.4 6.5 6.6 6.7

Shiitake cultivation on plastic bags Substrate preparation Filling and heat treatment Spawning Spawn run and mycelial development Fruiting Harvesting Pests and diseases

58 58 59 59 60 61 63 63

7 7.1 7.2 7.3 7.4 7.5

Wood ear mushrooms on ‘sterilised’ substrate Substrate preparation Heat treatment Spawning and spawn run Fruiting Case description: the Philippines

65 65 65 65 66 66

8 8.1 8.2

Post harvest handling Fresh Market Drying

69 70 71

Appendix 1: Formulas

76

Appendix 2: Substrate preparation

77

Further reading

78

Useful addresses

81

Glossary

83

Contents

5


1

Introduction

Do you want to grow mushrooms? There are plenty of reasons to do so. Mushrooms are a good cash crop; they are rather easy to grow and are brimming with protein, B vitamins and minerals. They even have medicinal properties. Time between spawning and harvesting can be as short as three weeks. Furthermore, after the cultivation, you can still use the substrate as a good soil conditioner. This Agrodok gives you detailed information on the cultivation of oyster, shiitake and wood ear mushrooms. Although many other types of mushrooms can be grown, we have chosen the ones that can easily be cultivated in developing countries using appropriate technology. When choosing your method to grow mushrooms, you have to find an answer to the following questions: 1 Which of the mushrooms do you want to grow? Check the market and the temperature ranges for fruiting (see paragraph 2.4). 2 Can you obtain mushroom spawn (the “seed�) of the species you want to grow? Chapter 4 shows you how to produce your own spawn. If you cannot obtain or produce spawn it will not be possible to grow mushrooms. 3 What kind of substrate would you need to be able to grow the desired mushrooms? See Chapter 5. 4 How should you treat the substrate? This affects the investments you have to make. Details can be found in the chapters on the specific mushroom species. To understand mushroom growing and the properties of mushrooms, some biological knowledge of the crop is necessary. So, we will start with the biology of mushrooms.

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Figure 1: The three mushroom species dealt with in this Agrodok

Introduction

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2

Biology of mushrooms

2.1

Fungi

Mushrooms belong to the kingdom of Fungi, a group very distinct from plants, animals and bacteria. Fungi lack the most important feature of plants: the ability to use energy from the sun directly through chlorophyll. Thus, fungi depend on other organisms for food, absorbing nutrients from the organic material in which they live. The living body of the fungus is mycelium made out of a tiny web of threads (or filaments) called hyphae. Under specific conditions, sexually compatible hyphae will fuse and start to form spores. The larger sporeproducing structures (bigger than about 1 mm) are called mushrooms. In nature this is the most striking part of the organism, but in fact it is just the fruiting body and the major part of the living organism is found under the ground or inside the wood. Scientific and colloquial names of mushrooms The scientific names of mushrooms are often used in this Agrodok, as they give rise to less confusion than colloquial names. For example, the name oyster mushroom applies to more than 20 different species of mushroom, each with its own cultivation characteristics such as optimal temperature range, colour and growth rate.

For mushroom growers, the most practical approach to the subject of taxonomy is to rely on taxonomists. It is best to order strains from renowned spawn producers or culture collections.

2.2

Fungus ecology

Fungi depend on other organisms for their food. Three modes of living can be recognised: ? Saprophytes: degrading already dead material ? Symbionts: living together with other organisms (especially trees) in a close, mutually beneficial relationship ? Parasites: living at the expense of other organisms 8

Small-scale mushroom cultivation


The mode of living has nothing to do with edibility: both edible and poisonous mushrooms can be found in all three groups. This Agrodok only deals with saprophytes. Saprophytes Saprophytic fungi need organic matter to decompose. In nature they will grow on fallen leaves, animal droppings, or stumps of dead wood. Some are specialised in breaking down the hairs of mammals, while others may decompose birds' feathers. Saprophytes decompose the complex organic structures left behind by plants and animals. And in the natural run of things, plants or animals regain access to minerals and other nutrients present in the substrate. Oyster mushrooms degrade dead wood in nature. They can be cultivated on a wide range of ligno-cellulose waste materials.

2.3

Life cycle of fungi

Fungi multiply by producing millions and millions of spores. When a spore settles in a suitable environment, it can germinate and branch to form a mycelium. When two sexually compatible mycelia meet, they may fuse to form a so-called secondary mycelium, which is capable of forming fruiting bodies. Mycelial growth and spawn In the practice of edible mushroom cultivation no use is made of spores. Their small size makes them difficult to handle and their genetic characteristics may differ from those of their parent. Moreover, it takes some time for mushroom spores to germinate, whereas other fungi such as green moulds germinate and spread much faster.

The desired mushroom must be able to colonise the substrate before other fungi or bacteria do so. To achieve this, pre-grown mycelium (free of any contaminants) of the mushroom is inoculated on a sterile substrate. This material is referred to as spawn. Using spawn will give the cultivated mushroom an advantage in growth over other fungi.

Biology of mushrooms

9


Spawn run The mycelium will colonise the substrate and use the available nutrients. This is commonly referred to as the spawn run. When some nutrients run out, or when the weather changes, the mycelium will reach a different phase: the reproductive stage. A temperature of about 25 째C is optimal for the spawn run of most species. The environment can also enhance the growth of the desired mycelium: a high CO2 concentration is favourable for mycelial growth (but not for cropping).

Figure 2: Life cycle of mushrooms in nature

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Figure 3: Life cycle from mushrooms to spawn. Tissue cultures are isolated from a mushroom and propagated on a suitable substrate. This full-grown substrate is then used in mushroom growing.

After having colonised the substrate, the mycelium is capable of producing fruiting bodies. The number and quality of the fruiting bodies will depend on the environment. Key factors to induce fruiting bodies are: ? changing temperature ? high humidity ? deficiency of a nutrient ? CO2 concentration in the air ? light ? physical shock

Biology of mushrooms

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These factors differ from mushroom to mushroom. Most of the changes that stimulate fruiting have a negative effect on the vegetative growth of the mycelium. Changes should therefore only be made when the mycelium has completely grown through the substrate. It is actually the less favourable condition for vegetative growth that will stimulate the mycelium to fruit. Two examples to induce fruiting in different mushrooms: ? Some oyster mushrooms (for example Pleurotus ostreatus strains) will fruit reliably when, after mycelial growth, they experience a cold shock (a difference of 5 째C to 10 째C). The CO2 concentration has to be lowered as well. Mycelial growth can take place in the dark, but light is essential for fruiting. ? Fully-grown shiitake (Lentinula edodes) mycelium in substrate bags are soaked in water for one or two days and receive a physical shock to stimulate fruiting. The shock will remove captured CO2. Small primordia (initial fruiting bodies) will be formed at the beginning of the reproductive phase. Under the right conditions, these primordia will develop into fruiting bodies. Nutrients are transported from the mycelium to the fruiting bodies by a steady moisture flow. Water has to evaporate on the surface of the mushrooms in order to allow the flow to continue. This explains why spraying water on maturing mushrooms or a too high relative humidity of the air can spoil the crop.

2.4

Temperature ranges of cultivated mushrooms

Choose a species that fruits at temperatures near your outdoor temperatures. This limits investments in climate control and reduces energy costs. As the table shows there are actually few species suited to really tropical conditions. The only mushrooms currently being cultivated at temperatures around or just below 30 째C are: oyster mushrooms (Pleurotus cystidiosus / abalones / ostreatus var. florida) and

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Volvariella volvacea, Agaricus bitorquis, Stropharia rugoso-annulata and wood ear mushrooms (Auricularia politricha). Table 1: Temperature ranges and techniques for mycelial growth, optimal growth and fruiting for specific mushroom species. Mushroom species/ Common name Tmg Toptimal mg Tfruiting Techniques Lentinula edodes /Shiitake 5-35 20-30 8 -25* 1, 2, 3, Pleurotus abalonus /Abalone oyster 15-35 20-30 25-30 2, 3 mushroom Pleurotus cystidiosus /Oyster mushroom 10-35 25-28 25-30 2, 3 Pleurotus ostreatus /Winter oyster mush- 5-35 20-25 5-25 2, 3 room Pleurotus pulmonarius /Oyster mush5-35 20-25 13-20 2, 3 room Pleurotus cornucopiae# / Branched or 15-35 20-28 15-25 2, 3 yellow Oyster mushroom Pleurotus djamor ^ /Pink oyster mush15-35 24-30 20-30 2, 3 room Pleurotus eryngii /King oyster mushroom 10-35 20-25 15-22 2, 3 Auricularia polytricha /Wood ear mush20-35 35-30 23-28 2 room #: Including Pleurotus citrinopileatus ^: Including probable synonyms: P. ostreatus, P. salmoneo-stramineus, P. flabellatus Tmg: The range at which the mycelium stays viable; the growth speed declines at both high and low ends of this range. Toptimal mg: The optimal temperature range required for fruiting; the most important temperature. Substrate preparation techniques: 1 Wood logs (not treated in this Agrodok) 2 Pasteurised or pre-heated substrate 3 Sterilised substrate

Biology of mushrooms

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3

Mushroom farms

Certain factors should be kept in mind when selecting a site for a mushroom farm: ? distance to the market ? availability of good quality substrate material ? transportation of both product and substrate material ? ready availability of clean water

Figure 4: Cropping house

3.1

Farm layout

Before one can start to plan the layout, the processes to be performed at the mushroom farm will have to be listed. For example, whether or not an inoculation room is required depends on whether growers prepare their own substrate or buy inoculated substrate.

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The farm layout should also include: ? An efficient flow of substrate materials ? Measures to prevent contamination on the farm ? Efficient use of space The mushroom farm should provide suitable climatic conditions. It is possible to adapt existing structures such as defence tunnels, bunkers, caves, chicken houses, old milk factories and slaughterhouses. Some successful mushroom cultivation operations take place in old defence or railway tunnels. Floors On a low investment level, mushroom houses are just built on arable land. On a higher investment level, cemented floors are used. Slightly inclined cemented floors provide a smooth surface that can easily be cleaned and allow excess water to drain.

A screened basket could be used to collect the coarse debris from the drained water. The drainage system of the different rooms should not be connected to prevent a disease in one growing room from easily spreading to other rooms. The floors should also be smooth to facilitate handling and transport of materials. Doors, windows and other openings Doors and walls should close properly to prevent insects from entering the growing rooms. A double door, with a wire mesh for the second entrance, can help to keep insects out. The same rules apply for windows. The openings through which air is either blown in or out of the rooms should have at least a simple filter or cloth as barrier. The smell of mushroom mycelium is very attractive to mushroom flies.

Mushroom farms

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Figure 5: Double door at the entrance of the incubation unit

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3.2

Farm hygiene

Hygiene is vital on a mushroom farm. Since chemical control of pests and diseases is not possible in small-scale mushroom cultivation, the only preventive measure is hygiene, and to some extent disinfection. This goes for a spawn production unit, the site for substrate production, the incubation rooms and production units. Therefore checking a suitable site for a mushroom farm is very important. The surroundings of a farm should be clean and free from possible contamination from insects, moulds etc. This means that building a new farm close to other mushroom farms should be avoided. Insects and diseases from these farms could easily spread to the new farm. If possible separate the various units of the new farm.

The spawn laboratory should be separate from the growing site. The growing rooms ought to be separated by (plastic) walls to keep the different stages of cultivation apart. As a matter of fact no incubation or spawn running should take place in the same room where the mushrooms are harvested. Debris, contaminated bags and spent substrate must be removed immediately from the rooms and from the farm itself, preferably to a place far away.

All these measures are necessary to avoid pests such as flies and other insects as well as diseases spreading from these waste dumps. If the spent substrate is to be used for gardening soil, it should be used as soon as possible.

Mushroom farms

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4

Spawn production

The mushroom “seed” (propagation material) is generally referred to as spawn. Availability of spawn culture The availability of good quality spawn is the limiting factor for mushroom cultivation in many developing countries. Customs’ bureaucracy, high shipping costs and the difficulty to keep the spawn cooled during transport, often hinders imports. It might therefore be necessary for the mushroom grower to produce his own spawn. If good quality spawn of the desired mushroom species can be obtained at a reasonable price, it would be wiser to concentrate on the mushroom growing process. If not, spawn will have to be produced or multiplied by the mushroom grower.

The complete procedure of spawn production involves preparation of the medium, filling the test tubes or Petri dishes and sterilising them, and the process of inoculating larger containers with this culture. Spawn production requires a clean laboratory and specialised knowledge.

Basically, spawn production is nothing more than putting mycelium of the desired mushroom in suitable sterilised substrates under aseptic conditions. In practice, however, producing spawn is not that simple. Suitable strains from the required mushroom species have to be maintained under strict conditions to avoid degeneration. If this is not possible tissue culture from a fresh and healthy mushroom should be used for spawn production. In addition, the spawn production room has to be kept meticulously clean to avoid any contamination.

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Figure 6: Multiplication of spawn

Spawn production

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4.1

The starter culture

The starter culture (or mother culture) can be made from a fresh and healthy fruiting body or obtained from a spawn producer or laboratory. More agar cultures are then made from this starter culture. These serve to inoculate larger containers (like bottles) with mother spawn, which can be used to inoculate the final spawn substrate. The minimal requirements for a spawn production unit are: ? a sterilisation unit (pressure cooker, autoclave) ? sterile environment: inoculation box or laminar airflow cabin ? laboratory equipment like Petri dishes, test tubes, scales, alcohol, flame ? incubation room The above equipment is commonly available in hospitals, research stations and universities. The raw materials include: ? ingredients for media preparation ? substrate material (grain, wooden sticks (skewers), sawdust, or even oil palm fruit fibre) ? pure culture or fresh mushroom of the desired mushroom species strain ? spawn containers (such as bottles or plastic bags) In countries lacking mushroom production, spawn may be obtained from a spawn producer, a university or a research station at the start of a project. For addresses of spawn producers see Useful Addresses.

4.2

The sterilisation process

Grain, sawdust and compost contain large numbers of contaminants. A single grain kernel may contain thousands of bacteria, fungi and actinomycetes.

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Every one of these undesired agents, which are called contaminants, is capable of spoiling substrates that have not been properly sterilised or inoculated under unhygienic conditions.

A heat treatment of 15 minutes at 121 째C is usually sufficient to kill all organisms. It takes quite some time for the steam to heat the inner core of substrates to this temperature, depending on the way the sterilisation/pasteurisation unit is filled and on the capacity of the burner. Steaming in an oil drum for at least 6 hours is usually necessary to ensure proper heating of the inner core of the substrate bags. Sterilise 4-liter bags filled with 2kg spawnsubstrate for at least 2 hours at 121째C.

Pressure cookers The cheapest option is to obtain one or more large pressure cookers. Select pressure cookers that maintain the pressure when the final temperature has been reached.

The simplest pressure cookers blow out steam when the pressure is too high. The pressure inside will then often drop below 1 atmosphere overpressure, causing the media to boil.

Figure 7: Pressure cooker for use on a burner and an electric pressure cooker

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This should be avoided. Petri dishes or bottles with agar media may become messy if this type of pressure cooker is used. The pressure cookers should have an inside rack, which will effectively ensure a more even temperature distribution inside the pressure cooker. The heat source is either external (gas burners, coal, wood) or built-in (electric). The advantage of pressure cookers with thermostatically controlled electric heating elements is that they allow for precise temperature regulation.

4.3

Clean environments

A clean environment is absolutely essential to spawn production. In particular, whenever the containers with sterilised media need to be opened it must be done under aseptic conditions. The air carries numerous contaminants, which easily infect the sterilised media. It is therefore necessary to use special cabinets and inoculation rooms for performing the handling and the preparation of the (tissue) cultures. Inoculation rooms The interior of the inoculation room should consist of nonbiodegradable materials. All the surfaces should be smooth and easy to clean. Shelves should be designed in such a way that the floor beneath can be cleaned easily. Shelves are typically made of galvanised iron or Formica. Inoculation cabinets These simple inoculation cabinets are widely used all over the world. They can be constructed cheaply from locally available materials. The front glass pane can be opened to fill the cabinet with the sterilised media. The inside is disinfected by cleaning with a 10 % Clorox solution, a 2% Formalin solution or 70% ethyl alcohol. Take care when using these chemicals. Some of them are poisonous and/or irritating to nose and eyes. Cautiously follow the instructions to ensure safe use.

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Figure 8: Simple homemade inoculation cabinet showing front glass pane on hinges and holes (with cloth sleeves attached) for hands. Laminar airflow cabinets A laminar airflow system (LAF) consists of a fan, a duct, a HEPA (High Efficiency Particle Air) filter and a hood.

In laminar airflow contaminants can spread in only one direction. In turbulent airflow it is possible that spores move in different directions, causing more contamination. The ventilators are rated by the producers according to the volume of air they can blow through materials of specified resistance. About 0.45 m/s air Figure 9: A ready made laminar velocity is considered best for airflow cabinet good laminar airflow. The fan

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should be regulated stepwise and have the capacity to push double the amount of required air through the filter to reach the required air velocity, to account for pressure losses when the filter gets loaded with particles. In many countries both HEPA filters and these specific ventilators are not available and have to be imported.

The filters and ventilators are the heart of any laminar airflow system, but other factors have to be considered too: the operating persons, their skills and their hygiene; the construction of the ducts and filters to ensure that no contaminated air can be sucked in.

4.4

Cultures

The first steps in spawn production are performed on artificial media. These should contain sufficient nutrients for the mushrooms to grow, like saccharides and a solidifying agent (agar or gelatine). The mycelium grows on the surface of the medium and will later be used to inoculate larger amounts of substrates like sawdust or grain. Test tubes or Petri dishes (or flat whiskey bottles) can be used as culture containers. Instead of working with cultures, one could also try to purchase small amounts of good quality mother spawn to prepare the final spawn.

Tissue cultures Young and vigorous mycelium can be obtained from a young fruiting body using a scalpel, alcohol, sterilised agar slants, Petri dishes or bottles with agar, flame (non-smoking), and a clean table to work on, or preferably a laminar airflow cabinet or inoculation box.

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? Wash the mushroom thoroughly. ? Dip the scalpel in alcohol, and then flame it until red-hot. ? Let it cool down for 10 seconds. ? Now break or tear the mushroom lengthwise (do not cut it with a knife, since contaminants from the Figure 10: Which part to surface can stick to the blade). Do use in shiitake (left) and not touch the inner surface with oyster mushroom (right) your hands. ? Use the heated scalpel to remove a small piece (2x2 mm2 is sufficient) of the inner tissue. Take care that no outside surface tissue is included. ? Open the test tube/Petri dish. ? (When using test tubes: heat the mouth of the tube in the flame to kill unwanted spores). Then, gently replace the tissue on the scalpel in the middle of the agar. ? Immediately replace the plug. ? Inoculate at least three cultures, but preferably more. Incubate the newly inoculated agar slants or Petri dishes at 25 째C for about ten days. Within three to four days mycelium will cover the tissue and branch out on the agar. If no growth occurs on the agar, check the following: ? Possibly the mushroom was too old. Try a fresher specimen. ? Possibly the scalpel did not cool down before taking the tissue sample, thereby overheating the mycelium.

The mycelium should be white and grow out from the tissue. If yellow, blue, green or grey mycelia form on other places on the surface, then these are fungal contaminants. A creamy, shiny growth often indicates bacterial contamination.

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Figure 11: Preparation of the spawn

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Small-scale mushroom cultivation


4.5

Preparation of media

Most species grow on the following media: Potato Dextrose Agar (PDA) extract medium Ingredients: 200g diced potato, 20 g agar powder, 20g dextrose or ordinary white sugar, 1 litre water. 1 Wash and weigh the potatoes and cut them into small pieces. 2 Boil for about 15 to 20 minutes until they are soft. 3 Remove the potatoes. 4 Add water to the broth to make exactly 1 litre. 5 Add the dextrose and the agar. Be sure to add the right amount of sugar and agar, otherwise the medium will become either too soft or too hard. 6 Stir occasionally and heat gently until the agar has melted. The agar should be hot when poured into the test tubes or bottles otherwise it will become lumpy. 7 Fill about one fourth of the test tubes. 8 Then, seal the tubes or bottles with cotton plugs. Rice bran broth medium The above recipe for PDA is commonly used for culture preservation, but for multiplying cultures, the following recipe is cheaper and easier to prepare. It is in use in the Philippines for oyster mushroom (Pleurotus) and wood ear mushroom (Auricularia).

Ingredients: 200 g rice bran, 1 litre water, 20 g gelatine. Boil the rice bran for about 10 minutes in the water. Filter, save the broth and melt the gelatine and pour into bottles and sterilise.

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4.6

Preparation of slants

After filling the test tubes or bottles with the medium, they must be sterilised before they can be used. The most commonly used sterilisation units in small-scale laboratories are pressure cookers, but autoclaves can be used as well. Procedure ? Pour water into the pressure cooker to the level of the rack. ? Place the bottles/test tubes in the racks with a plastic covering to prevent water from wetting the cotton plugs. ? Then close the lid firmly. ? The air vent should be open at the beginning to allow the air to escape. This will take some minutes from the moment of boiling and steam escape. ? Close the air vent. A pressure gauge shows the pressure rise. ? Sterilise under pressure for 20-30 minutes. To increase the surface area, the test tubes or bottles are placed in an inclined position when the agar is still fluid. Take care that the agar does not touch the cotton plug otherwise it might become contaminated. Do not move or handle the test tubes until the agar has solidified, otherwise a small portion of the agar may solidify at the other side of the slant or too close to the plug.

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Figure 12: Preparation of the Potato Dextrose Agar (PDA) medium (1,2,3) and preparation of bottles (4,5,6)

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Sub-culturing Inoculate more test tubes using the methods discussed above.

Figure 13: Sub-culturing (part 1)

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Figure 14: Sub-culturing (part 2) For reasons of degeneration it is advisable not to transfer from one mother culture more than eight times or to use mother cultures on agar for more than two years.

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The mycelium will degenerate after a certain number of transfers, so it is not possible to keep on transferring the cultures on agar forever. Spawn containers Spawn containers should be made out of heat resistant material: mostly glass and polypropylene (PP). The spawn containers have to be tested to see if they can withstand the temperature inside the sterilisation unit. If the pressure is greater than 1 atmosphere overpressure, the temperature will be higher than 121째 C. PP bags sometimes crack easily after having been subjected to the sterilisation process. Avoid bags with seams: these tend to split after the heat treatment.

Glass or heat-resistant plastic bottles are often used for the mother spawn. Wide-mouthed jars, milk bottles and dextrose bottles can also be used. Dextrose bottles are ideal, because they can be obtained for free from hospitals and they have air outlets that can easily be plugged with cotton wool. They can be used for final spawn too, but if the mycelium from the spawn material has grown into one big clump, the bottles have to be broken to get it out. Polypropylene bags with cotton plugs (or filters) to allow aeration are much in use for the final spawn (both sawdust and grain). Their size varies between 2.5 and 15 litres for grain spawn. The exchange of metabolic gases like CO2 with ambient air has to be ensured; unwanted spores, however, must be prevented Figure 15: Bags sefrom entering the container.. aled with a cotton plug.

4.7

Mother spawn

Mother spawn can be used to inoculate either grain spawn or a second generation of mother spawn. In simple laboratories, grain mother spawn should not be used to inoculate another generation of grain mother spawn because the risk of contamination and degeneration will be too high.

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Preparation of grain spawn The main advantage of grain is that it is very nutritious for fungi and forms kernels easily. The kernels can easily be dispersed in the substrate. The main disadvantage is that it provides an optimal substrate for other organisms too. The chances of contamination are therefore much higher compared to sawdust spawn. Kinds of grains Different grains can be used such as wheat, rye, millet, rice or sorghum. Boil grain first, drain, then fill in containers and sterilise.

The moisture content of the grain, after boiling, should be around 50%. If it is higher, mycelial growth may be faster, but the danger of wet spot bacteria is also greater. If it is drier than 35% mycelial growth will be rather slow. Grain spawn formula Grain in small containers can be moistened to a higher degree than grain in 15 litre bags. For 2 litre containers, use the following recipe: 480 g rye, sorghum or wheat, 400 ml water, 2 g gypsum (45% moisture). (See Appendix 1) Preparation of sawdust spawn Sawdust spawn substrate: Sawdust 10 kg, CaCo3 147.5 g, Rice bran 1.25, Gypsum 0.1475g, Urea 0.5 g, Water 1.5 litres. (See Appendix 1) Sterilisation Sterilise the spawn containers in an autoclave. The length of time depends on the autoclave, the way the spawn containers are packed (dense or loose) and the size of the containers. For instance, two hours for 500 g containers; three to four hours for 3 kg bags. Shake the bottles when taking them out of the autoclave or the pressure cooker.

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Inoculation Once the temperature in the centre of the container has dropped to below the maximum mycelial growth temperature, the spawn containers can be inoculated. Use at least one (for 250 ml bottles) or two (for bigger bottles) squares of 10 x 10 mm² from the full-grown agar of the mother culture for each bottle. Incubation Incubate the bottles until the mycelium has grown all over the substrate. The temperature should be close to the optimal temperature for mycelial growth (consult Table 1 in Chapter 2). Shake once (after eight days) or twice during the incubation period (or every three or four days) to distribute the mycelium evenly and to prevent kernels from sticking together.

Storage Keep the spawn in the refrigerator (except for certain strains of Pleurotus djamor spawn, which are cold sensitive and should be stored above 12 °C) and only take it out when needed. Grain spawn can spoil in one night at temperatures above 25 °C.

4.8

Preparation of the final spawn

The choice of a specific spawn substrate depends on the chosen species and the cultivation method. The following table shows which spawn substrates are most frequently used. Table 2: Use of spawn substrates. Species Shiitake /Lentinula edodes Oyster mushroom /Pleurotus spp. Wood ear mushroom /Auricularia spp.

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Cultivation method Sterilised sawdust in bags Pasteurised or sterilised substrates Sterilised substrate in bags

Final spawn substrate Grain, sawdust Grain, sawdust or straw based spawn Sawdust

Small-scale mushroom cultivation


Sawdust or grain spawn? The advantage of sawdust spawn is that it can be kept at a higher temperature much longer before it spoils. The substrate material is also cheaper than grain. Sawdust based spawn is made in the same way as described in the chapter “sterilised” substrates, except that it needs to be sterilised at 121°C under pressure.

Figure 16: Preparation of sawdust spawn in glass bottles. The mouth of the bottle is cleaned to prevent spores from germinating.

An advantage of grain spawn is its vigour. A disadvantage is that it spoils rapidly and is very nutrient-rich and thus more susceptible to contamination. Grain spawn is unsuitable for outside use, as rodents will eat it. Grain spawn causes a faster temperature rise in the inoculated substrate than sawdust spawn, which may or may not be desirable. Grain is treated the same way as discussed above for the mother spawn. It may be inoculated by grain spawn or wooden sticks.

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Storage and purity Good spawn shows vigorous mycelial growth and contains no other organisms. If it has been stored too long it will become less vigorous. Spawn from oyster mushrooms, for instance, will become very compact after prolonged storage. As a consequence it will be difficult to apply evenly during spawning.

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5

Growing oyster mushrooms on pasteurised or ‘sterilised’ substrates

Substrate The material on which the mycelium of the mushrooms grows is called substrate. Agricultural waste like wood chips/sawdust, sugar cane bagasse, and different types of straw can be used as the main ingredients in the substrate for oyster mushrooms.

The properties of a substrate determine which mushrooms and microbes can grow in it. The more selective it is, the better the substrate meets the demands of a specific mushroom and the less suitable it is for others. After mixing and adding certain supplements, the substrate undergoes a heat treatment to give the desired mushroom mycelium an environment with few competitors.

5.1

Preparation of the substrate

Oil drums and plastic bags are all you need to prepare the substrate. A cemented floor is the preferred underground for mixing and moistening the sawdust (or straw) and a fork for mixing the ingredients. Substrate preparation equipment: ? substrate mixer (optional); the mixing of the substrate ingredients can be performed just as well manually ? a steam source or heating equipment like an oil drum For the substrate: ? raw substrate materials, like sawdust, rice bran, wheat straw, dried banana leaves, dried elephant grass, dried grass pieces etc. ? substrate containers (plastic bags or bottles)

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? depending on the type of bags/bottles: additional plugs and plastic rings and/or rubber bands Mixing the substrate The aim of mixing is to distribute the different ingredients, including water, as evenly as possible. If adding a small quantity of one component like chalk, then it is better to mix it first with some of the substrate and only then add it to the large heap. Otherwise its distribution will probably remain non-uniform. Moreover, lumps might occur and the very high concentration of nutrients at these spots will result in contamination.

Mixing is also very important for the moisture distribution. The correct amount of water should be available everywhere in the substrate. After mixing, the moisture content should be 60 – 65%. Sometimes a better distribution can be achieved if the substrate ingredients are mixed in a dry state (e.g. in “sterilised” substrates containing sawdust and supplements); the water is then added later.

. A batch of up to 2000 kg can be mixed by hand on a cemented floor, similar to cement making. Two people are capable of manually mixing 2 tons of substrate per day. More people, however, should do filling. Sterilise the substrate as quickly as possible after mixing in the supplements. Storage of the mixed ingredients for a period longer than 6 hours should be avoided to prevent fermentation of the substrate.

Sawdust substrate The sawdust (or other bulk substrate material) has to be stacked on a heap and moistened. By keeping the heap moist, the sawdust will soften. This will ease the absorption of water. Usually the sawdust is stacked for only one or two days.

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If only fresh sawdust is available, like sawdust from recently felled trees, it should be stacked for a much longer period: up to several weeks. The sawdust substrate should be free of splinters or bigger pieces of wood. These may damage the bags, offering contaminants easy access after sterilisation. On the other hand, several growers feel that a cobination of fine and coarser sawdust or wood chippings provides the best starting material. Very fine sawdust should be avoided as it clogs the airflow when moistened. Straw substrate Moisten the finely chopped substrate ingredients and apply the squeeze test to determine whether the substrate is moist enough.

Figure 17: Squeeze test Filling the bags Fill small substrate containers (usually plastic bags) with the substrate before sterilising.

Growing oyster mushrooms on pasteurised or ‘sterilised’ substrates

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Figure 18: Filling the bags

5.2

Heat treatments

The aim of the heat treatment is to kill competing microorganisms and to get rid of soluble nutrients. Most substrates are given a heat treatment before spawning. It is an important measure to control pests and diseases. In this Agrodok three methods are dealt with: ? pasteurisation by immersion in hot water ? pasteurisation by steam ? sterilisation

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Table 3: Advantages and disadvantages of different heat treatments. Heat treatment Fresh substrate pasteurised by immersion in hot water

Comments Simple method

Equipment Wood fire or solar energy can easily be used

Feasible for several agricultural wastes, like coffee pulp waste, straw, sawdust

Fresh substrate pasteurised by steam

Little chance of contamination because easily soluble carbohydrates are removed by the immersion process Good method to handle large amounts of substrate Use of agricultural wastes like straw, corncobs, cotton seed hulls

Fresh substrate “sterilised”

More chance of contamination than with immersed or sterilised substrate Good method for bags of sawdust

Steam boiler and pasteurisation room necessary Oil drum on fuel burner

Simple method: oil drums on fuel burner Expensive method: autoclave

Immersion in hot water This method is a form of pasteurisation. The hot water will kill contaminants. Different types of straw can be treated in this way for the cultivation of oyster mushroom (Pleurotus) The method is very easy: only hot water, containers and the means to keep the water hot are required.

Materials and equipment required: ? substrate material (see formulas in appendices 1 and 2) ? substrate containers (e.g. plastic bags or trays) ? containers for hot water and means to keep the water hot (fuel, solar energy, steam, etc.) ? wire mesh to let the substrate drain

Growing oyster mushrooms on pasteurised or ‘sterilised’ substrates

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Figure 19: Immersion and draining of straw

The substrate is put in wire mesh cylinders in hot water. The water has to be kept at 70 째C for at least 15 minutes, but 30-60 minutes is safer. Immersion in water at lower temperatures and for periods shorter than 15 minutes is insufficient to kill all contaminants.

The size of the water containers depends on the scale of the operation. A 240-litre container can hold about 90 kg of wet straw substrate. The same container can be used 2-3 times a day, because the actual immersion time is only about 30 minutes to one hour. The same batch of water should not be used for more than two or three batches of substrate.

Draining and cooling Drain the heat-treated substrate and let it cool on a clean plastic sheet on a table or on the floor inside the farm. Then spawn as described in paragraph 5.3 (Spawning pasteurised substrates).

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Bulk pasteurisation by steam This method kills the unwanted organisms but keeps the favourable ones alive. To achieve this, a temperature of 60 ºC to 70 ºC has to be sustained for at least 8 hours; after which most pests and diseases (contaminants) will be eliminated.

Materials and equipment required: ? substrate material (see formulas 4-6 in appendix 2) ? substrate containers (e.g. plastic bags) ? oil drum and burner Put a rack in the oil drum, with a fine mesh wire to prevent straw from falling through. Fill water below the rack to a height of 20 cm. Then add the moistened straw on top. Steam the straw for at least 8 hours. Take care that the straw has cooled down to 30 C before spawning. Allow the steam to escape through small openings to prevent explosion of the drum.

Sterilisation This method too is used to kill unwanted organisms but here the temperature is much higher and there is overpressure in the container or oil drum.

When simple equipment is used the reached temperatures will not be higher than 90°C and the pressure in the container cannot build up very high. Good results, however, have been obtained by prolonged heating at this temperature when the substrate should be sterile. To avoid an explosion, make sure that tightly closed drums or containers have a safety valve in the lid.

Materials and equipment required: ? substrate material (see formulas 1-3 in appendix 2) ? substrate containers (e.g. plastic bags)

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? oil drum (re-enforced), or metal container. Make sure that materials used are able to withstand the temperatures At higher altitudes water will cook below 100째C. In that case also, the period of heating should be prolonged.

5.3

Spawning pasteurized substrate

The substrate should have cooled down (whether pasteurised by steam or by immersion in hot water) to 30 C. The spawn (3% to 8% of the weight of the substrate) can be mixed in with when filling the bags. Or a layer of substrate can be topped with some spawn, layer by layer. See figure 27. Different types of bags can be used to hold the substrate. Never fill to more than 20 kg per bag: spontaneous fermentation would raise the temperature inside the bags to more than 30 째C, the upper limit for mycelial growth of most oyster mushroom species. Make holes in the bags to ensure that enough oxygen can reach the substrate. One type of bag used in China is made of cylindrical plastic, 20 cm in diameter, filled up to a height of 50cm, with a perforated pipe in the middle, right down to the bottom of the bag. The mouth of the bag is tied around the pipe, and aeration proceeds through the pipe. The aeration pipe will also allow heat to dissipate, even if it is formed in the core of the substrate. Spawn run: It will take the mycelium 20 days at 25 째C to colonise the substrate. The plastic and aeration channel can be removed entirely if a very humid environment can be created, for example in a shed. Alternatively, the plastic can remain around the substrate, in which case cuts have to be made in the plastic to enable the mushrooms to grow out.

5.4

Spawning sterilised bags

The substrate should be spawned as soon as it has cooled below 30 째C. Relatively large amounts of spawn are used: 7 to 10%. If smaller percentages give similar results, then there is no need to stick to these figures.

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Spawning is performed by lifting the plugs from the bags containing the substrate (thus opening the bags) and putting in a small amount of spawn. This is the moment at which contamination is most likely to occur. So ensure that the time the bags are open is as short as possible!

Figure 20: Steps in spawning procedure

During the process of spawning the following measures need to be taken to control contamination of the substrate: ? Put on clean clothes. ? Put the hot bags in a special room with UV lights. Let the bags cool down without ventilation, or ventilate with filtered air. ? Do the spawning on the following day (do not forget to turn off the UV light). ? Hold both substrate and spawn containers in a horizontal position to prevent spores falling in. ? Use a flame near the mouths of the bottles of spawn and plastic bags to keep the environment more or less sterile.

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? Spawning should take place at night when there is less contamination in the air. ? Clean with chemicals: formalin or alcohol. Be careful not to come into contact with these chemicals. The use of chemicals can affect both health and environment; health measures should be considered first.

Misting with H2O2 is an environment-friendly way to obtain a clean room for spawning, as its end products are oxygen and water. Using Oil drums A simple oil drum can be used in the following way: ? Place a wooden rack on the bottom of the oil drum at a height of around 20 cm. ? Fill the drum with water up to the height of the rack (20 cm). ? Place the bags with the substrate on the rack inside the oil drum. ? Put the lid on the drum and steam for four to six hours by heating the drum with either wood or gas.

Allow the steam to escape by a few small holes. Each time about 75 bags can be steamed in this way. Take care to add enough water and to supervise the heating Figure 21: Simple sterprocess in order not to boil away all the ilisation unit prepared from an old oil drum. water. Steaming unit Relatively simple tent-like constructions can also be used to semisterilise the bags. Prolonged heating at around 96-98 째C will sterilise the substrate sufficiently. Obviously the materials used should be able

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to withstand the temperatures. Insulation panels can keep energy costs down. After the heat treatment the substrate should be sterile. Autoclaves Autoclaves are double-walled steel containers, which are able to withstand an overpressure of 1 atmosphere. Large autoclaves require a high investment and are therefore not discussed further in this Agrodok.

5.5

Spawn run

During spawn run stage the mycelium will grow through the substrate. The spawn run time is different for each species and depends on the size of the bag, amount of spawn, the strain used and the temperature. Once the bags are spawned they should be placed on shelves in the incubation rooms. Depending on the strain and temperature the mycelium will colonise the substrate in two or three weeks and start to form small fruiting bodies. As a consequence either the conditions in the growing room will have to change, or the bags need to be moved from the incubation room to the growing room.

Next, remove the cotton plugs and (a part of) the plastic and ensure that high humidity is maintained: 90 to 95%. If, however, the relative humidity is rather low do not cut away too much plastic to prevent the substrate from drying out. When the pinheads have grown to a size of 1 cm, the humidity should be lowered somewhat to 85% by passing fresh air through the room.

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5.6

Fruiting/cropping

Several techniques are used for filling the mushroom house and making the bags ready for fruiting. A common practice is to make bamboo or wooden frames and stack the bags on them to form a wall of plastic bags. Opening the bags Open the bags as soon as the mycelium has covered the substrate completely. Remove the cotton plugs and cut away the plastic top of the bag (partially). Take care not to cut too deep or else you would damage the mycelium.

Figure 22: Oyster mushroom fruiting.

If you want to get small mushrooms, a larger surface should be exposed to the open air. Note; this will result in the substrate drying more rapidly. It takes three to four days after opening the bags before the primordial buttons/mushrooms will form. Hanging the bags Another method is to slash each bag and hang them from the ceiling.

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Figure 23: . Different ways to cut the plastic of the spawned substrate bags after the mycelium has fully grown through the substrate.

Small-scale mushroom cultivation


Temperature The ambient temperature has to fit the chosen mushroom strain. If the temperature in the mushroom house is too high for the chosen strain, it will be necessary to frequently mist the house. Opening the doors and windows at night will also help keep the temperature down. Aeration/ventilation The mushroom house needs ventilation openings that may also provide light. Light Oyster mushrooms are very sensitive to insufficient aeration and light. Required light (colour and intensity) depends on the strains. Some growers adhere to the rule of thumb that light should be sufficient to read a newspaper everywhere in the growing room.

When the small mushrooms emerge, their form will reveal whether they get sufficient light and aeration. If the stems are long and the caps small, the aeration and light requirements were not met. In the complete absence of light, oyster mushrooms will form no cap but stipes (mushroom stalks) forming a coral-like structure. Humidity Good control of the humidity during cropping is very important for all types of mushroom. Keep the humidity high (80 - 90%) by spraying water several times per day. However, no water should be sprayed directly onto mushrooms that are ready for picking. Their shelf life will decrease drastically if they become too wet.

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Figure 24: Maintaining a high humidity during cropping is important for all mushrooms.

5.7

Harvesting

The mushrooms are ready for harvesting in five days (if the temperature is between 15 and 20 째C) or two to three days (at higher temperatures). It will take another five to nine days for the second flush. There is so much variability among strains and substrates used that it is difficult to give periods for fruiting. Typically, it will take about one week before new primordia are formed, but much depends on the local climate conditions and the climate control in the growing rooms. Harvesting is performed by gently pulling or twisting the mushrooms from the substrate. Only very little substrate should be pulled out.

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Rubbing instead of scraping Some growers in the Philippines scrape off some of the substrate to free it from small, undeveloped primordia. These would easily become infected and have to be removed, but scraping the substrate will also retard the formation of new primordia. Rubbing the surface of the sawdust bags is a better method to remove the small and already dead fruiting bodies without causing harm to the mycelium.

Harvesting can continue as long as the mycelium remains white and firm. In total, three or four flushes can be harvested. When the substrate becomes soft and colourless, it is time to remove it from the house. Do not throw the spent substrate near the mushroom houses! All waste should be removed from the working areas immediately. Pests and diseases present in the used substrate can too easily spread to the fresh substrate.

Mushroom yields vary according to biological factors, environmental conditions, as well as pests and diseases present during cultivation. The yield from commercial production is about 20% of the weight of the wet substrate of fresh oyster mushrooms. Product handling In order to avoid rapid deterioration, the fresh mushrooms should be marketed directly after harvesting. If this is not possible the mushrooms could be dried in a simple drying unit and marketed later. See Chapter 8, Post harvest handling.

5.8

Case description: Ahmedabad, India

Aryan AgroTech organisation runs a spawn laboratory and a mushroom production farm. In addition to these activities Aryan AgroTech organises oyster mushroom growing projects for minority groups, which the Gujarat government financially supports to a certain extent.

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The projects are selected mostly in tribal regions and the groups receive information and training sessions. After training, the selected persons are provided with materials for construction of a growing unit as well as basic materials for the cultivation. Growing House The growing house consists of a bamboo skeleton of about 2.5 metres high with a 50-m² surface. Plastic netting is placed over this skeleton, which is then covered with jute. Inside the growing rooms triangular platforms (4-high) of bamboo sticks hang from the bamboo roofing poles. Temperature control Temperature control is done to some extent by wetting the jute covering. The evaporation that will take place will lower the temperature in the growing rooms. Temperature can be lowered by several degrees, depending on the outside temperature and air current through the netting,.

Figure 25: Triangular hanging constructions

In the rainy period, however, the outside temperature is around 40 °C. During this period the cultivation is stopped there because the inside temperature cannot be lowered sufficiently to continue growing. From the point of farm hygiene this seasonal break in the growing of mushrooms is a good way to prevent outbreaks of pests and diseases.

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Figure 26: Spraying the jute-covered roof Preparing the substrate The substrate is made of wheat straw that has already been chopped into short pieces during threshing. This wheat straw is immersed in a drum with hot water (70 °C) and kept there for 2 hours, maintaining the water temperature at 70 °C using a wood fire or a burner.

Then the straw is taken out and placed on a grid or a piece of plastic to drain excess water (see Figure 21). Spawning the substrate Following the heat treatment and when drained, the moisture content of the straw substrate will be about 60%. The substrate is then put in layers in plastic bags. Spawn is placed on each layer. The spawning rate is about 10 % of the weight of the substrate (see Figure 29).

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The grain spawn is produced in the spawn laboratory in Ahmedabad. After filling and spawning the 3.5 kg bags are then moved into separate rooms for incubation. The incubation process will take 3 weeks, preferably at a temperature of 25 °C. Once the bags are fullgrown with mycelium, holes or cuts are made in the bags in order to provide aeration for the fruiting bodies to develop (see Figure 25). Figure 27: Spawning in layers. Harvesting When the fruiting bodies have developed in mushroom clusters they are ready for harvesting. Harvesting of the mushroom clusters can be done for a period of at least 3 weeks. The stems are cut off. Stems and mushrooms are marketed separately. A part of the mushrooms is sold fresh in local markets. The rest is dried and sold at a fixed price to Aryan AgroTech.

5.9

Case description: Bogor, Indonesia

The Women’s Farmer group ‘Hanjuang’ at Bogor, Indonesia, was initiated some years ago in order to stimulate housewives to start agricultural activities in their free time. The revenues provide additional family income, which is mainly used for school fees and medical expenses. Various activities such as seedling nurseries for ornamental plants and fruit trees as well as home industry have been started. One of the activities of the Women Farmers Group “Hanjuang” at Bogor is the cultivation of oyster mushrooms mainly Pleurotus ostreatus

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var. florida. Spawn is produced on sawdust substrate in their own lab from tissue cultures. Construction of the growing house The production houses have a surface area of about 35 m² and are about 3 metres in height. They are constructed out of wooden or bamboo poles and bamboo leaf mats. The roofing is often reinforced with plastic. The shelves in the houses (5 high) are also constructed out of bamboo. Substrate preparation The substrate used is sawdust. Formula: 10 kg sawdust, 1.5 kg rice bran, 200 gram chalk, 30 gram gypsum and 15 litres of water.

This well mixed substrate is put in 2-litre PP bags and pressed to make so-called bag logs weighing about 1.2 kg. The opening is closed with a PVC ring and a cotton wool plug after which these bag logs are sterilised for 8 hours in closed drums. Spawning the bag logs After cooling down, the bag logs are spawned. The spawn is put through the top opening, which is then sealed with the cotton wool plug. The cotton wool is then covered with paper.

Spawn is produced on sawdust substrate in their own lab from tissue cultures. Incubation After being spawned the bag logs are placed in an incubation room. The incubation room is clothed well in plastic sheeting along the ceiling and the walls in order to maintain a constant temperature of 30 C. The bag logs are kept in the incubation room for about 3 weeks.

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Fruiting Once the bag logs are full grown with mycelium they are placed on bamboo shelves in the production house. The paper covers and cotton wool plugs are removed from the bags in order to provide aeration and stimulate cropping and fruiting. Temperature During the daytime the temperature in the incubation room reaches about 26 째C with a relative humidity of 90%. Harvesting and marketing When the mushroom clusters are mature they are picked, slightly trimmed and sold in the local markets and/or occasionally to supermarkets.

5.10 Juncao Technology turns grass into mushrooms In 1983, Professor LIN Zhanxi of Fujian Agricultural University recognised the rapid decline of forests in China as wood logs were much in demand for shiitake and other exotic mushrooms. He started to work with wild grasses, bagasse, rice and corn straw as basic materials for the mushroom substrate. In 1987 he decided to name the technique JUNCAO: Jun from fungi, and Cao being the Chinese word for grass(es). Now, 21 years later, the technique has led to a comprehensive growing system for more than 40 types of mushrooms, using some 33 kinds of leguminous plants as basic substrate material. The grasses are dried after the harvest, ground and stored until used. Specific substrate recipes have been developed for each mushroom. For example a patented process has been developed to use protein from fermentative bacteria instead of the commonly used wheat bran. Heat treatments and substrate containers also vary between species. This systematic set of technique has spread to at least 50 countries and helped to alleviate poverty while making sustainable use of resources which are readily available.

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Table 4: Common and scientific names of grasses and legumes Common name alfalfa, lucerne banana brazilian lucerne common reed elephant grass foxtail millet giant reed peanut reed grass setaria grass sudan grass swamp foxtail, fountain grass water lettuce wild ranking fern wild sorghum

Scientific name Medicago sativa Musa nana Stylosanthus Phragmites communis Pennisetum purpureum Setaria italica Arundo donax Arachis stylosanthus Arundinella nepalensis Setaria sphacelata Sorghum arundinaceum var. sudanensis Pennisetum alopecuroides Pistia stratiotes Dicranopteris ampla Sorghum proquinuum

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6

Shiitake cultivation on plastic bags

The cultivation of shiitake in sterilised plastic bags is rapidly gaining popularity. Mushrooms can then be harvested faster and the yield is higher compared to growing on wood logs. Filling the bags and sterilising them, however, is labour intensive and energy consuming. The main advantages of growing shiitake on bags are: ? Many types of organic waste can be used. ? Total cropping period is 6 months compared to 4 to 6 years with cultivation on woodlogs. If the substrate has been compressed and only little spawn has been used, the incubation period is three to four months.

6.1

Substrate preparation

The most commonly used substrate formulations are: ? Sawdust, 3 to 4% rice bran, 1% corn meal or wheat bran, 1% CaCO3 ? Sawdust, 10 to 25% corn waste, 1 to 2% CaCO3 Fresh sawdust from the trees of the genera Quercus, Betula, Castanopsis, Castanea, and Carpinus can be used without prior fermentation. Sawdust from other trees can also be used, but if the sawdust contains resins it has to ferment for a number of months (stack on a moist heap for 1 week, turn after one week, and then once every month for up to 6 months). When the sawdust is moist enough it has to be mixed with the supplements and the chalk. Mix the chalk first with the rice bran, as it will be easier to get an even distribution.

The moisture content (apply the squeeze test, see figure 17) at the time of preparation is usually between 55-65% of the substrate and in58

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creases during incubation; take care to compare the right data (e.g. always measure before sterilisation). Some reports indicate that a high water-holding capability of the substrate combined with good aeration will give better results. Substantially higher yields have been reported when (tea)leaves were mixed with the above-mentioned substrate as described for oyster mushrooms. If the substrate is too moist, the airflow will be clogged and even a long spawn run period will not deliver a high-quality substrate. If water collects at the bottom of the bags, the substrate is certainly too wet.

6.2

Filling and heat treatment

Check the general procedures for filling. In Taiwan steaming at a temperature of 96 - 98 째C showed better results than sterilisation under pressure at 121 째C, but both methods can be used. Steaming under low pressure is appropriate if more flushes are expected. Ample space between the crates and bags should provide sufficient steam circulation.

6.3

Spawning

Let the bags cool down and spawn them the next day. 10 g of sawdust spawn is sufficient to spawn one bag of 1.2 kg so one bottle of 550 ml is sufficient for about 50 bags. The strain for sawdust cultivation should be checked carefully. Some serious losses in yield have occurred because spawn makers sold new strains that produced well on wood logs, but gave very low yields on sawdust. Some strains will perform better on a substrate of corncobs; others better on a sawdust substrate.

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Take the usual precautions when spawning; use the measures for spawn making if extreme levels of contamination occur. Not more than 5% of the bags should become contaminated.

6.4

Spawn run and mycelial development

It will take one to four months for the mycelium to colonise the substrate and mature, depending on the type and the amount of spawn (refer to the case studies). For fruiting some light should be provided for at least the end of the spawn run. Growers who have completely dark spawn run rooms should illuminate the room with a day/light cycle at the end of spawn run. Problems can be avoided if a little light is present during all stages of the growth. All strains show optimal mycelial growth at 25째C. The temperature inside the bags is usually a few or even ten degrees higher than the ambient room temperature. If many bags are packed in a room, extensive cooling may be necessary. Growth stages Five different stages of mycelial growth of all strains of shiitake can be distinguished for all strains. The first phase is the normal spawn run as it occurs in all fungi. When the substrate has turned white, it is not ready to fruit. It has to mature first.

The following are the five stages: 1 Mycelial running: The spawn will give rise to white hyphae, which produce enzymes to degrade complex substances like cellulose, lignin and hemi cellulose into smaller fragments. The fragments will be consumed at later stages of mycelial growth. As soon as the complete substrate is colonised, the next phase is entered. 2 Mycelial coat formation: A thick, white mycelial sheet will develop on the surface of the substrate. This will occur in two to four

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weeks after inoculation. If the CO2 level is high, the sheet will be thicker. 3 Mycelial bump formation: Bumps are clumps of mycelium, commonly formed on the surface by most strains. These bumps can turn into primordia at a later stage, but most of them fall off. Fluctuating temperatures and a high CO2 level promote bump formation. If many bumps are formed decrease the CO2 level by slitting the plastic open. The bumps may become a problem at a later stage of the cultivation, because green moulds can easily contaminate them. 4 Pigmentation phase: Some aeration should be provided when the bumps have formed. The mycelium will turn reddish-brown. If, however, the plugs are removed entirely, the substrate may dry out too much. 5 Coat hardening phase: Remove the plastic when bags have partially (half or one-third) turned brown. The outside of the substrate (coat) will have gradually become hard, while the inside should be softer and moister. The moisture content of the substrate core (inside) can be as high as 80%. If the outside is relatively wet, contaminants will have easy access to the substrate. The brown hard skin acts like the bark in wood log production: it protects against contaminants and keeps the humidity in the substrate. It is important to regulate climate conditions to obtain a mycelial coat of the right thickness.

6.5

Fruiting

The same factors that promote fruiting in shiitake cultivation on wood logs are used to manipulate the flushes in plastic bag cultivation. These are: ? temperature fluctuation ? high humidity ? soaking ? removal of CO2 ? physical shocks

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If the plastic is removed too early or too late, yields will be affected. De-formed fruiting bodies during the first flush are a sign of a spawn run being too short or CO2 too high during incubation. Strains differ in mycelial growth rate. While 60 days is sufficient to mature one strain, another strain would yield many deformed mushrooms after the same period of maturing. If the temperatures are rather low and a suitable strain has been used, high-quality donko mushrooms can be harvested. If the humidity is also relatively low (60 to 70%), then cracks may appear in the caps of the most expensive quality in the Far East, which is called “flower winter mushroom” (hua dong gu) in Chinese. Table 5: A typical time schedule for shiitake cultivation on sterilised substrates (from: B. Chalmers) Stage/activity

Days

Incubation Induction of fruiting bodies Harvesting

30-120 2-4

Temperature (°C) 20-30 1 10-20

7-14

12-18

Recovery

7-21

20-30

1

Light intensity (Lux) None 500-1000

Relative humidity 65-70% 85-95%

500-1000

60-80%

None

65-70%

2

Induction of 2-4 10-20 500-1000 85-95% fruiting bodies 3 for second flush 1 The temperature range for fruiting is dependent on the strain. 2 A dry period after harvesting will prevent contaminants from spoiling the substrate at the scars where the mushrooms have been picked. 3 The artificial logs may be given a cold water bath to restore a high moisture content of the substrate. Substrate blocks do not need to be watered during incubation.

If substrate is spawned on top only, most mushrooms will emerge from the top (see Figure 28). If the spawn has been mixed thoroughly, shiitake mushrooms will emerge from all sides.

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6.6

Harvesting

Hold the mushrooms by their stalks and break them off carefully from the substrate. Do not tear them from the surface otherwise too much substrate will be torn loose. Harvest the mushrooms at an early stage according to the quality requested by the buyers. Do not water the scars left behind for three or four days. White mycelium growing on the scar is a sign of recovery. Completely opened mushrooms have a much lower value in Asia, whereas buyers in Europe are less critical. Normal yields are 15 to 35% of the wet substrate weight.

Figure 28: Shitake fruiting on top of vertical bags

6.7

Pests and diseases

Green moulds Green moulds are the most common contaminants at the moment of spawning. They will also grow if there are any cracks in the bags. The substrate should be kept dry in between the flushes. Moist conditions promote contamination, and contamination attracts flies, which spread contamination even further.

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The shiitake mycelium will normally form a crust below the Trichoderma colony. It is best to spray the green moulds after the harvest with a strong flush of water. However, if the substrate is too soft (because the moisture content is too high), the block would be damaged and consequently it will be more difficult to obtain a good second flush. Mushroom flies Mushroom flies are attracted by the odour of the mycelium. They may occur in batches of old bags. The flies as such do not harm the mushrooms but they lay eggs between the lamellae and on the mycelium. Larvae will hatch from the eggs and will spoil the crop.

The only solution to tackle this problem is to consistently remove the old bags as well as the contaminated bags, and to clean the rooms. Mites Mites may crawl into the incubation bags (if bags with plugs are used) and contaminate the substrate. However, the plastic bags will generally form a good barrier against insects, which makes this method of substrate packaging most suitable for countries with a high infection pressure.

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7

Wood ear mushrooms on ‘sterilised’ substrate

Wood ear mushrooms (Auricularia spp.) are commonly cultivated in Asia. Plastic bag cultivation is gaining popularity due to the scarcity of suitable logs and the ease with which different species of Auricularia can be cultivated on sawdust. The technology can be expected to spread in the near future. There are many Auricularia species of which Auricularia polytricha, Auricularia fuscosuccinea and Auricularia auriculu-judea are the most commonly grown. Auricularia polytricha is the most suitable species to cultivate in tropical regions where temperatures are high.

7.1

Substrate preparation

The formula for the sawdust substrate is about the same as for oyster mushroom and shiitake, but the moistening period (fermentation) of the substrate should be longer. The preparation of the bags is again the same.

7.2

Heat treatment

The filled bags are steamed in the same way as for oyster mushroom and shiitake.

7.3

Spawning and spawn run

Sawdust spawn is generally used, 10 ml of spawn per bag is sufficient. During the spawn run the temperature should be 25º to 28º C. The mycelium will cover the substrate in about four weeks.

Wood ear mushrooms on ‘sterilised’ substrate

65


7.4

Fruiting

Cuts in the bags are made so the mushrooms can emerge. Take care when handling the bags, because the texture of the substrate will stay soft even after the mycelium has colonised it. The mycelium is very sensitive to breakage.

Only little light should be present in the mushroom house. Three to four flushes can be expected. Per bag of 1.2 kg, 300 – 500 g can be harvested.

7.5

Case description: the Philippines

Although the market in the Philippines is more favourable for the smaller Auricularia auricula-judae (the black wood ear mushroom), the temperature range there is more suitable for growing A.polytricha. A. auricula-judea can only be grown in cooler areas. Substrate preparation (weight percentages) ? Dry sawdust (moisture content 15-18%) 78 kg ? Fine rice bran (first class) 21 kg 1 kg ? CaCO3

The rice bran has to be sifted to break bigger particles into smaller pieces. The bigger particles would be the first to become contaminated. Weigh the substrate ingredients and mix CaCO3 and rice bran well before mixing them with the sawdust. Add water slowly until the moisture content is 65-70%. (Check with the squeeze test, figure 17) Fermentation Pile the substrate in pyramids and cover with plastic to retain its moisture. Let the heap ferment for five days and turn the heap on the third day. Sieve through 1.5 mm mesh to remove bigger particles and to break the clumps that may have formed during fermentation. The bigger particles might damage the plastic.

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Small-scale mushroom cultivation


Filling Pack about 1 kg per 12 x 30 cm bag and add the ring and the plug.

Figure 29: Putting rings on substrate bags. Heat treatment Sterilise the filled bags for 1.5 hours at 121º C or semi-sterilise for 10 hours at a temperature just below 100º C. Spawning and spawn run Use one 500 ml of spawn for 50 bags. The spawn run takes about one month at 25º – 30º C. Place the bags flat in rows on shelves.

A mushroom house (5 m wide, 12 m long and 4 m high) can hold 2640 bags. Each row has 55 bags per layer; four layers per row. Four rows with 220 bags each can hold 880 bags, so that three shelves may hold 2640 bags.

Wood ear mushrooms on ‘sterilised’ substrate

67


Fruiting and harvesting The optimum fruiting temperature of wood ear mushrooms (Auricularia polytricha) is 23º – 28º C. To promote primordia formation, the cotton plugs should be removed from the bags and holes cut in the bottom. Try to keep the temperature below 30º C by spraying water and opening the mushroom house at night. The primordia will develop into fruiting bodies in seven to ten days. Twist the fruiting bodies from the substrate by hand, leaving no bits of stem behind.

68

Small-scale mushroom cultivation


8

Post harvest handling

The edible mushroom is a highly prized product. It has a short shelf life. Special conservation methods have been developed, most of which are described in this chapter. This chapter pays attention to: ? Quality grades and harvest ? How mushrooms can be packed for the fresh market ? How they can be conserved for future consumption Quality grades and harvest Mushrooms should be picked at the stage at which they have the highest profitability. Mushrooms should be dry on the surface when they are picked. Spraying (or rain) a few hours before picking reduces the shelf life of most cultivated mushrooms.

Picking The pickers should gently break the mushrooms from the substrate or casing soil. Tearing away chunks of mycelium from the substrate or casing soil should be avoided. After picking, the mushrooms are cut to the desired stem length. Since mushrooms can easily be damaged it is best if handling is kept to the minimum. Immediate grading at picking and packing them in the same packages in which they will be sold will ensure that they are touched only once; at the moment of picking.

Instruct pickers to stringently stick to the following rules: ? Always pick mushrooms from newest beds/rooms first ? Do not touch sick fruiting bodies (collect them at the end of picking in a separate bag, disinfect hands and clothes of the involved worker afterwards) Post harvest handling

69


Oyster mushrooms (Pleurotus) can either be harvested in bundles or as single fruiting bodies. Some concepts of oyster mushroom cultivation rely on harvesting whole bundles (e.g. oyster mushroom cultivation in Japan in bottles). This particularly applies to Pleurotus ostreatus and Pleurotus cornucopiae. Harvesting and marketing young bundles of oyster mushrooms has the following advantages: ? Many mushrooms can be picked in a brief period ? The mushrooms look nice and stay fresh longer ? And the buyers also pay for the stems Oyster mushrooms, however, are often sold as individually cut mushrooms. They should be picked when the outer margin of the fruiting bodies has only just rolled inwards, on the verge of becoming horizontal. Storage time will increase if they are picked at a stage just before maturation. Stipe length should be discussed with the buyer. Shiitake (Lentinula) Cut the stems immediately after picking. Cut the stems with a sharp knife (where the mushroom was attached to the substrate). Debris from stems will make the mushrooms dirty. Wood ear mushrooms (Auricularia) Twist the fruiting bodies from the substrate by hand leaving no pieces of stem behind.

8.1

Fresh Market

Under ideal conditions, packed mushrooms for the fresh market are covered with a plastic film and cooled rapidly after harvesting. The plastic film provides good protection from water loss, as long as the storage temperature is more or less constant. Repeated exposure to fluctuating temperatures should be avoided.

70

Small-scale mushroom cultivation


If the temperature rises, the mushrooms will lose water. If the temperature drops, water will condense inside the package and on the surface of the mushrooms. This will lead to fast wilting. Pleurotus spp.: Experiments in the tropics have shown that keeping the mushrooms at 8-10 째C in pre-packs wrapped in perforated polyethylene films is a good way to keep mushrooms fresh. They can be kept for four days.

Conservation methods The taste and nutritional value of fresh mushrooms is usually better than that of conserved mushrooms. Nevertheless, conservation methods are necessary when only part of the harvest can be sold fresh.

Canning, brining and drying are the most common techniques, but not all conservation methods are equally suitable for all the different types mushrooms. Canned oyster mushrooms, for instance, taste horrible (except for Pleurotus cystidiosus and P. abalonus). In some cases, the taste may become stronger after the conservation treatments. Oyster mushrooms and shiitake, for example, give off a specific fragrance after drying.

8.2

Drying

This process is rather easy to perform. Drying has several advantages: it is easy, quick and safe and well-dried mushrooms can be stored for a long time. Among cultivated mushrooms, this conservation technique is mostly used for shiitake (Lentinula). The shiitake mushrooms get tastier after the drying process. Oyster mushrooms (Pleurotus) also become tastier. Nevertheless, the market for dried oyster mushroom is smaller compared to the market for dried Shiitake. Wood ear mushrooms (Auricularia) can be dried as well and are often marketed in this way.

Post harvest handling

71


Watch the following points during drying: ? The mushrooms should not touch each other. ? Air circulation is very important; put the mushrooms on a grill rack or a metal grid. ? The area around the drying oven should be well ventilated to provide fresh dry air, while the moist air can flow out. Mushrooms do not have to be crisp to the touch after drying; they should still be slightly flexible. As the mushrooms could become toasted at high temperatures, longer drying at low temperatures is safer than faster drying at high temperatures. If the fresh mushrooms are very wet, the starting temperature should not be low as they might start to rot. This is especially important for large whole mushrooms. Drying by sun The quality of sun-dried mushrooms is generally less than that of artificially dried ones. The moisture content of sun-dried mushrooms is higher and therefore they can be kept for a shorter period than the artificially dried ones.

Figure 30: Drying trays

72

Small-scale mushroom cultivation


Figure 31: Indirect sun dryer Artificial drying: Revolving driers are suitable for mass production. The starting temperature for shiitake should be 30째C and increased hourly by 1 or 2째C until it reaches 50째C in 12 to 13 hours. The final touch is heating the mushrooms up to 60째C for one hour to increase the luster of the cap. Fluctuations in drying temperature will cause the cap to wrinkle, according to Chinese growers.

Post harvest handling

73


Figure 32: Improved indirect sun dryer Drying by ventilation: A low energy input method of drying is by constructing a simple plastic tunnel and blowing in cold air from one side. The freshest mushrooms should be added downstream, as they lose much water through evaporation. Packing and storage All foreign material should be removed at the end of the drying process. Dried products easily absorb water from the surrounding air because of their low water content, so packing has to take place in a dry

74

Small-scale mushroom cultivation


room. It is a good idea to finish drying during the warmest part of the day when the relative humidity is at its lowest. The product can be cooled in the shade and if the work is done hygienically, the cooled products can be packed immediately. The packing material must be waterproof, airtight and insect-proof. The dried products will only remain good if stored in such a way that they are dry and protected from insects. Normal plastic bags (properly sealed) will do for some time, but are not entirely gas and waterproof. It is also possible to use polymer-coated cellophane bags, which are waterproof and airtight. These can be sealed with a hot iron or a sealing machine (where electricity is available). Unfortunately this kind of plastic cannot be easily obtained and is not too strong either. A plastic bag of thicker quality (polyethylene, 0.05 mm thick) is best. These can be closed tightly with a metal clip or with cellophane tape.

Post harvest handling

75


Appendix 1: Formulas Formulas for media PDA: Potato Dextrose Agar extract medium 200 g diced potato, 20 g agar powder, 20 g dextrose or ordinary white cane sugar, 1 litre water. Rice bran broth medium 200 g rice bran, 1 litre water, 20 g gelatine. Boil the rice bran for about 10 minutes in the water. Filter, save the broth and melt the gelatine and pour into bottles and sterilise. Formulas for spawn substrate Grain spawn substrate Grain in small containers can be moistened to a higher content than grain in 15 litre bags. For 2 litre containers, use the following recipe: 480 g rye, sorghum or wheat, 400 ml water, 2 g gypsum (45% moisture). Sawdust spawn substrate Sawdust 10 kg, CaCo3 147.5 g, Rice bran 1.25g, Gypsum 0.1475g, Urea 0.5 g, Water 1.5 liter

76

Small-scale mushroom cultivation


Appendix 2: Substrate preparation Substrate preparation (weight percentages) 1. Dry sawdust (moisture content 15-18%) Fine rice bran (first class) CaCO3

2.

Sawdust Rice bran Cornmeal / Wheat bran CaCO3

3.

Sawdust Corn waste CaCO3

78 % 21 % 1% 94 % 4% 1% 1% 89 – 73 % 10 – 25 % 1– 2%

Recipes 1- 3 can only be used when the substrate is sterilized. The mentioned supplements like corn meal or bran would contaminate quickly in substrates which have been pasteurized only. 4.

Rice straw CaCO3

98 % 2%

5.

Wheat straw CaCO3

99 % 1%

6.

Wheat straw

100 %

Appendix 2: Substrate preparation

77


Further reading Literature on mushroom cultivation

Edible and poisonous mushrooms of the world, 2003, New Zealand Institute for Crop and Food Research, by I. Hall, et al. ISBN 0-47810835-4. 370 Pages of general information on mushrooms: which wild mushrooms to pick, how to grow them, poisonous mushrooms of the world, and 250 high quality colour pictures. JUNCAO Technology, 2001, by Z.X. Lin and Z.H. Lin. China Agricultural Scientech Press, Beijing. ISBN 7-80167 210-0. 250 pages on the use of different types of grasses for 13 different types of mushrooms, including shiitake, white button and oyster mushrooms. Very promising technology for developing countries. JUNCAO Research Institute, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, People’s Republic of China, 350002. Phone: 0086-591-83789223/83789208, Fax: 0086-591-83769269 E-mail: ljuncao@sina.com Mushroom biology and mushroom products, 1993, edited by S.T. Chang, J.A. Buswell and S.W. Chiu. Chinese University Press, Hong Kong. ISBN 962-201-610-3. Contains the Proceedings of the First International Conference on Mushroom Biology and Mushroom Products in 1993 in Hong Kong, 37 scientific articles on fundamental aspects of mushroom biology, nomenclature of edible mushroom species, cultivation and bioconversion technology, post-harvest treatment, and nutritional and medicinal aspects. An interesting volume for research stations. Two articles deal with the implementation of mushroom projects. Mushrooms: Cultivation, Nutrional Values, Medical Effects and Environmental Impact, second edition, 2004 by S.T.Chang and P.G.Miles. CRC Press (www.crcpress.com) ISBN 0849310431. $ 160.

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Small-scale mushroom cultivation


Mushroom Cultivation, Appropriate technology for mushroom growers, third edition, 2003 by Peter Oei, Backhuys Publishers, Leiden, The Netherlands. Also available from CTA = no. 1146, 40 credit points. ISBN 90-5782-137-0 Mushroom Growers' Handbook 1 : Oyster Mushroom Cultivation, 2004. MushWorld (www.mushworld.com) Obtainable from Mushworld. Mushroom Growers' Handbook 2 : Shiitake Cultivation, 2005. MushWorld (www.mushworld.com) Obtainable from Mushworld. Shiitake Growers Handbook: The Art and Science of Mushroom Cultivation, Paul Przybylowicz and John Donoghue. ISBN 0-84034962-9 Price: approximately US$ 25. Gives detailed descriptions on how to grow Shiitake on both logs and sawdust substrates. It does not address sterile culturing and spawn production, assuming spawn is bought by the growers. Growing Gourmet and Medicinal Mushrooms, 2000 by Paul Stamets third edition 2000 by Paul Stamets, Ten Speed Press, Berkely, United States.(www.tenspeed.com) ISBN 00-0242584 Literature on taxonomy and identification of wild mushrooms

The atlas of cultivated Pleurotus mushrooms, by J.T. Peng, et al. 1990. ISBN 957-9055-03-3. Description of the cultivation parameters of 50 different strains of oyster mushrooms from the culture collection of CCRC in Taiwan. Edible mushrooms of Tanzania. 1995, by M. Härkönen, T. Saarimäki, and L. Mwasumbi. ISBN 951-45-6962-8 This work is a combination of ethno-mycological knowledge from Tanzania and modern natural sciences. The book (93 pages and colour pictures) covers the most important edible and poisonous mushroom species. It is the result of four field trips and hundreds of interviews

Further reading

79


with Tanzanians. Vernacular names, modes of preparation and an introduction on how to identify mushrooms are all discussed. KARSTENIA Vol. 35 suppl. 1995, Helsinki. ISBN 951-45-6962-8. An introduction to the larger fungi of South Central Africa, 1994 by L. Ryvarden, G.D. Piearce and A.J. Masuka. Published by Baobab, Zimbabwe. ISBN 0-908311-52-4 A guide to the most common edible and poisonous mushroom species in Malawi, Zambia and Zimbabwe. 200 pages and colour pictures. Contains more information than Edible mushrooms of Tanzania. The edible fungi south of the Sahara, 1993, by J. Rammeloo and R. Walleyn. A literature survey. Scripta Botanica Belgica 5: 1-62. The poisonous and useful fungi of Africa south of the Sahara, 1994, by R. Walleyn and J. Rammeloo. A literature survey. Scripta Botanica Belgica 10: 1-56.

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Useful addresses International society for mushroom science ISMS Secretary PO Box 11171, Centurion, Pretoria 0046, South Africa Phone: +27 12 665 2210; Fax: +27 12 665 2212 Email: secretary@isms.biz, Website: www.isms.biz Kali Mata Women's Group, Gezaulole, Tanzania Women's development centre in Tanzania. This centre has developed a project on mushroom cultivation. Kaifa Ally, secretary, POBox 36484, Dar es Salaam, Tanzania Phone: 0744853351 Kali Mata Ki Jai! Foundation Netherlands Information also in English and Swahili. Trui Goslinga-Lindeboom Houtlaan 25, 2334 CJ Leiden, Netherlands Phone: 0031(071)5157279, E-mail: kalimata@vrouwen.net, Website: www.vrouwen.net/kalimata Mushroom Business Mushroom Business is a two-monthly, international trade journal for the worldwide mushroom industry (growers and suppliers). It features articles on growing techniques, markets and marketing, cultivation tips, research, industry news, opinion, and more. The site of Mushroom Business has links to the major suppliers of mushroom equipment, training etc. Reed Business Information bv P.O. Box 16500, 2500 BM The Hague, The Netherlands Phone: +31 (0)70 441 5060, Fax: +31 (0)70 441 5902 www.mushroombusiness.com Mushworld: www.mushworld.com Non-profit organisation devoted to poverty alleviation in the world through mushroom growing, especially in developing countries.

Useful addresses

81


Mycelia: spawn manufacturer Jean Bethunestraat 9, 9040 Gent, Belgium Phone: +32 (0)9 / 228 70 90, Fax: +32 (0)9 / 228 80 28 E-mail: info@mycelia.be, Website: www.mycelia.be Spore Mushroom Products / Stichting ECO Consult Gargouille 1, 4007 RE Tiel, Netherlands Phone: + 31 (0)6 515 42 882, Fax 0344 630 225 Website: www.spore.nl Website of the author. Information on special plastic bags for spawn production and on international training activities. E-mail for training courses to info@spore.nl. World Mushroom Society: www.worldmushroomsociety.com The objective of the WSMBMP is to promote knowledge related to mushroom biology and mushroom products. www.fungitec.com, Website in English and Spanish Advisory, workshops, short courses and mushroom projects. ZERI (Zero Emission Research Initiative) This initiative promotes sustainable human development in Africa, and also provides information on mushrooms. ZERI Africa: UNDP/UNOPS Regional Project University of Namibia, Private Bag 13301, Windhoek, Namibia Phone: 206 3340, Fax: 206 3505, Website: www.zeri.unam.na PUM, Netherlands Senior Experts PUM sends senior experts to more than 70 countries in Africa, Asia, the Middle East, Latin America and Central and Eastern Europe. Upon request, PUM’s experts offer their skills and experience to businesses and organisations in places where these are most needed. In the course of their careers, PUM’s advisers have gained extensive experience in nearly every conceivable field. These experts are independent and work on a voluntary basis (they receive no wages). P.O. Box 93078, 2509 AB The Hague, The Netherlands Phone: (+31) (0)70 349 05 55, Fax: (+31) (0)70 349 05 90 E-mail: info@pum.nl, Website: www.pum.nl

82

Small-scale mushroom cultivation


Glossary Agar:

Anaerobic: Aseptic: Autoclave:

Bacteria:

Break: Button stage: Cellulose:

Culture: Culture medium:

Fermentation:

An extract from a seaweed used to solidify media: alternatively, (cheaper) gelatin may be used. Agar is available in bar or powder form. Without oxygen (o2). Sterile condition: no unwanted organisms present. A container, the contents of which can be heated up to 121°c. It must be able to withstand an overpressure of 1 bar; otherwise the temperature cannot rise sufficiently. Micro-organisms that may cause contamination in culture work. Grain spawn is very easily contaminated with bacteria. See flush The young mushrooms are still fully closed. An organic compound in wood, straw, etc. It is easier to degrade than lignin. Cellulose is probably best known as raw material to make paper. Cotton waste contains high amounts of cellulose; sawdust contains cellulose, hemi-cellulose and lignin. See mother culture. Micro organisms differ in their nutritional needs. A large number of different media have been developed; PDA-agar and Malt-agar can be used for most cultivated mushrooms. The process of composting. Easily accessible nutrients will be degraded by micro organisms which makes the substrate more selective. Unwanted fermentation may occur if the compost is still very ‘active’ or if thick layers or large bags are used. In that case the temperature rise inside the substrate will become too high for the desired mycelium.

Glossary

83


Flush:

Formol:

Free water:

Fruiting:

Germination: Gills: Hypha, hyphae: Incubation:

Inoculation: Lamellae: Lignin:

Micro organisms: (Mother) culture: Mother spawn:

84

The sudden development of many fruiting bodies at the same time. Usually there is a resting period between flushes or breaks. A 30% solution of formaldehyde used to sterilise areas. The gasses kill living micro-organisms and spores. The actual water available to the micro-organisms in the substrate. Water content is the absolute measure. Free water is related to the water film around each particle in the substrate and the concentration of salts in the water. The mycelium will form mushrooms in its reproductive stage. This is called fruiting as the mushrooms are actually the fruiting bodies of the mycelium. The spreading of hyphae from spores. the radially arranged, vertical plates below the cap of a mushroom on which spores are formed. Individual cells of mycelium. The period after inoculation (preferably at a temperature optimal for mycelial growth) during which the mycelium slowly grows through the substrate Transferring an organism into a specific substrate. See gills A difficult-to-degrade organic substance which, together with cellulose, forms the basis of wood, straw, etc. Microscopic organisms which are abundantly present in the air. And stick to every surface. A pure strain of an edible fungus growing on a medium. Spawn not meant for inoculating substrate, but for inoculating another batch of spawn.

Small-scale mushroom cultivation


Mycelium:

The network of hyphae that form the vegetative body of the fungus. Mushrooms are the fruiting bodies of the mycelium. Mycorrhiza: A symbiotic relationship between fungi and plants. Parasite: Organism that lives at the expense of others, usually causing diseases in its hosts. Ultimately it may cause the death of its host. Pasteurisation: Heat treatment applied to a substrate to destroy unwanted organisms but keeping favourable ones alive. The temperature range is 60-80째c. The treatment is very different from sterilisation, which aims at destroying all organisms in the substrate. Petri dish: A round glass or plastic dish with a cover to observe the growth of microscopic organisms. The dishes are partly filled with sterile growth medium (or sterilised after they have been filled). Petri dishes are commonly used to grow mycelium which will inoculate the mother spawn. Ph: A measure to describe acidity of a medium. Ph 7 is neutral; a higher figure means alkaline, lower acidic. Most wood-inhabiting mushrooms prefer a slightly acidic substrate. Pinhead: A term to describe a very young mushroom when the cap is pin-sized. Primordium: The initial fruiting body. Pure culture: An isolated culture of micro-organism without any other micro-organisms. Pure cultures are essential to the spawn production process. Relative humidity: The percentage of moisture in the air compared to the maximal amount that the air can hold at that temperature and pressure. Slant: A test tube with growth medium, which has been sterilised and slanted to increase the surface area.

Glossary

85


Spawn: Spawn run: Species:

Spent substrate: Spores:

Stipe: Sterile: Sterilisation:

Strain: Subculture: Substrate: Test tube: Tissue culture:

86

Mycelium growing on a substrate used as planting material in mushroom cultivation. The period of vegetative growth of the mycelium throughout the substrate after spawning. Fundamental unit of biological taxonomy. Generally spoken, two individuals belong to the same species if they can produce fertile offspring. The substrate remaining after the mushrooms have been harvested. The means of reproduction in fungi. In cultivated mushrooms they are formed on the gills and dispersed in the air. One mushroom can produce millions of spores. Stalk of the mushroom. Conditions: see aseptic. Destroying (completely) all micro-organisms present, by heat or chemicals. Spawn substrate always has to be sterilized prior to inoculation. A group of individuals within a species. Equivalent to “race” or “variety” in plants. A culture derived from another culture. the material in which the mycelium grows. A tube of thin, transparent glass closed at one end used in chemical and biological experiments. A culture made from the tissue of a young and healthy mushroom.

Small-scale mushroom cultivation


Agrodok 41

Small-scale mushroom cultivation - 2 Agaricus and Volvariella

Bram van Nieuwenhuijzen


Š Agromisa Foundation and CTA, Wageningen, 2007. All rights reserved. No part of this book may be reproduced in any form, by print, photocopy, microfilm or any other means, without written permission from the publisher. First edition: 2007 Author: Bram van Nieuwenhuijzen Editor: Janna de Feijter Illustrators: Bernard Lamote, Barbera Oranje Design: Eva Kok Translation: Rob Barnhoorn (language editing) Printed by: Digiggrafi, Wageningen, the Netherlands ISBN Agromisa: 978-90-8573-083-5 ISBN CTA: 978-92-9081-365-1


Foreword The first Agrodok on ‘Small-scale mushroom cultivation’, Agrodok no. 40, describes the technique of mushroom cultivation on substrates that only need heat treatment. Certain mushroom species however, like the Rice Straw Mushroom (Volvariella spp.) and the Button Mushroom (Agaricus spp.) can only be cultivated on fermented substrate or compost. Rice Straw Mushrooms are cultivated in the warmer climates of the tropical regions, whereas the growing of the Button Mushrooms predominantly takes place in more moderate climates. The process of composting for mushroom cultivation is more complex than the preparation of temperature treated substrates. For that reason it seemed appropriate to publish a second Agrodok that meets the demand and covers the lack of information on this specific subject. It describes the complete process of composting of agricultural wastes as well as the cultivation of the appropriate species mentioned above. Moreover, it proves to be necessary to treat the process of obtaining good quality spawn and spawn production (propagation material) in detail in a separate chapter. Special emphasis has been put on the minimum requirements for growing conditions, mushroom houses and equipment for both species in order to avoid problems and to be cost-effective. Additionally, attention has been given to harvesting and post harvest handling. A high demand for processed (mostly canned) mushrooms does exist in suburban and urbanised regions. Consequently the basics of mushroom processing have been covered in a separate chapter. Whereas knowledge on marketing in the field of small-scale mushroom cultivation is still rather poor, it also seemed appropriate to add a chapter on marketing in which the importance and possibilities of the local and regional market(s) are pointed out. September 2007, Bram van Nieuwenhuijzen and Janna de Feijter

Foreword

3


Contents 1

Introduction

2 2.1 2.2 2.3

Biology of mushrooms Fungi Life cycle of fungi Temperature ranges of cultivated mushrooms

8 8 9 12

3

Mushroom farms

13

4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Spawn production Availability of spawn Clean environments The sterilisation process Preparation of media Preparation of slants Cultures The starter culture Tissue cultures Mother spawn Preparation of the final spawn

17 17 19 22 23 24 26 26 28 30 33

5

Composting

35

6 6.1 6.2 6.3 6.4 6.5

Cultivation of Button Mushrooms (Agaricus spp.) Pasteurisation or peak heating Spawning Casing Harvesting and picking Case description Button Mushrooms

42 42 43 44 46 47

7

Cultivation of Rice Straw Mushrooms (Volvariella spp.) Case description Rice Straw Mushroom cultivation

50 54

7.1

4

Small-scale mushroom cultivation - 2

6


8 8.1 8.2 8.3 8.4

Harvesting and post harvest handling Harvesting Fresh market Preservation Drying

58 58 58 59 60

9

Marketing

63

Further reading

66

Useful addresses

68

Appendix 1: Formulas

72

Appendix 2: Air quality test

73

Appendix 3: Different origins of contamination

74

Appendix 4: Culture transfer in detail

76

Appendix 5: Formulas for compost

78

Appendix 6: Simple steaming systems

80

Glossary

82

Contents

5


1

Introduction

Since time immemorial people have gone into fields and woods to pick edible mushrooms. Nowadays some species of edible mushrooms can also be cultivated as cash crops. Certain species are rather easy to grow while others demand more specific cultivation methods and temperature. In general the life cycle of a crop is rather short (varying between some weeks and a few months) When the cropping cycle has been completed the spent mushroom substrate (SMS) can be used as a soil conditioner. Mushrooms contain a lot of proteins and minerals, several B vitamins and are regarded as a healthy food or food supplement. Moreover, due to certain chemical compounds valued for their medicinal properties, mushrooms gain more and more interest from the health food industry. In this Agrodok information is given on the cultivation of Button Mushroom, which is consumed worldwide, and Rice Straw Mushroom, which is much valued in Asia. The specific cultivation methods of each of these mushroom species have been described in separate chapters. Before deciding to grow either one of the species mentioned above it is wise to verify the following points: ? Check the temperature range in section 2.3 to decide whether the climate conditions are appropriate for cultivation. ? Are you able to prepare the required compost? Which kinds of agricultural wastes (and in what amounts) are available for compost preparation? ? Can mushroom spawn be purchased? If not, are you then sufficiently equipped to produce your own spawn? (See chapter 4) ? Is there a demand for mushrooms in the vicinity and in the nearby markets? (See chapter 9)

6

Small-scale mushroom cultivation - 2


Figure 1: Button Mushroom (Agaricus spp.): closed button (left), mature (field) specimen (middle) and cross section (right)

Figure 2: Rice Straw Mushroom (Volvariella spp.): egg stage (left), mature specimen (middle) and cross section (right)

Introduction

7


2

Biology of mushrooms

2.1

Fungi

Mushrooms (Fungi) are very different from plants. Plants can use energy from the sun directly through chlorophyll. Fungi lack this ability; they depend on other organisms for food. They absorb nutrients from the organic material in which they live. The living body of the fungus is not the fruiting body above ground, but it is the mycelium that is found under ground or inside plants or wood. The mycelium consists of a web of miniscule threads, which are called hyphae. When these hyphae are sexually compatible, the hyphae will fuse and start to form spores under specific conditions regarding temperature and moisture. The larger spore-producing structures (bigger than about 1 mm) are called mushrooms. Scientific and colloquial names of mushrooms The scientific names of mushrooms are often used in this Agrodok, as they give rise to less confusion than colloquial names. For example, the name Button Mushroom applies to several different species of mushroom, each with its own cultivation characteristics such as optimal temperature range, colour and growth rate.

For mushroom growers, the most practical approach to the subject of taxonomy is to rely on taxonomists. It is best to order strains from renowned spawn producers or culture collections. Fungus ecology Fungi depend on other organisms for their food. Three modes of living can be recognised: ? Saprophytes: such as Rice Straw Mushrooms, which degrade already dead material. ? Symbionts: living together with other organisms (especially trees) in a close, mutually beneficial relationship. ? Parasites: fungi that live at the expense of other organisms. 8

Small-scale mushroom cultivation - 2


The mode of living has nothing to do with edibility: both edible and poisonous mushrooms can be found in all three groups. This Agrodok only deals with saprophytes. Saprophytes Saprophytic fungi need organic matter to decompose. In nature they will grow on fallen leaves, animal droppings, or stumps of dead wood. Some are specialised in breaking down the hairs of animals, while others may decompose birds' feathers. Saprophytes break down complex organic structures of plants and animals in order to feed on them.

2.2

Life cycle of fungi

Fungi multiply by producing spores or through mycelial growth. When a spore settles in a suitable environment, it can germinate and branch to form a mycelium. When two sexually compatible mycelia meet, they may fuse to form a secondary mycelium, which is capable of forming fruiting bodies. Mycelial growth and spawn In edible mushroom cultivation no use is made of spores. Their genetic characteristics may differ from those of their parents. Moreover, it takes some time for mushroom spores to germinate, whereas other fungi such as green moulds germinate and spread much faster.

The mushrooms we want to grow as a cash crop must be able to colonise the substrate before other fungi or bacteria do so. To achieve this, pre-grown mycelium (free of any contaminants) of the desired mushroom species is inoculated on a sterile substrate. This material is referred to as spawn. Using spawn will give the cultivated mushroom an advantage in growth over other fungi that have to grow from germinating spores. Spawn run The mycelium will colonise the compost and use the available nutrients. This is commonly referred to as spawn run. When some nutrients

Biology of mushrooms

9


run out, or when the weather changes, the mycelium will reach a different phase: the reproductive stage. A temperature of about 25째 C is optimal for the spawn run of most species. The environment can also enhance the growth of the desired mycelium: a high CO2 concentration is favourable for mycelial growth (but not for cropping). After having colonised the substrate, the mycelium is capable of producing fruiting bodies. The number and quality of the fruiting bodies will depend on the environment.

Figure 3: Life cycle of mushrooms in nature

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Figure 4: Life cycle of cultivated mushroom. Tissue cultures are isolated from a mushroom and propagated on a suitable substrate.

Key factors to induce fruiting bodies are: ? changing temperature ? high humidity ? deficiency of a nutrient ? CO2 concentration in the air ? light ? physical shock These factors differ from mushroom to mushroom. Most of the changes that stimulate fruiting have a negative effect on the vegetative growth of the mycelium. Changes should therefore only be made when the mycelium has completely grown through the substrate. It is

Biology of mushrooms

11


actually the less favourable condition for vegetative growth that will stimulate the mycelium to fruit. Small primordia (initial fruiting bodies) will be formed at the beginning of the reproductive phase. Under the right conditions, these primordia will develop into fruiting bodies. Nutrients are transported from the mycelium to the fruiting bodies by a steady moisture flow. Water has to evaporate on the surface of the mushrooms in order to allow the flow to continue. This explains why spraying too much water on maturing mushrooms or a too high relative humidity of the air can spoil the crop.

2.3

Temperature ranges of cultivated mushrooms

Choose a species that fruits at temperatures near to your outdoor temperatures. This limits investments in climate control and reduces energy costs. As the table shows there are actually few species suited to really tropical conditions. Some mushrooms currently cultivated at temperatures around or just below 30 째C. are: Volvariella volvacea, and Agaricus bitorquis but most species prefer lower temperatures. Table 1: Mushroom species, temperature ranges (in 째C) for mycelial growth, optimal growth and fruiting, and techniques to be applied to the substrate Mushroom species/ Common name Tmg Toptimal mg Tfruiting Techniques Agaricus bisporus 10-32 20-28 10-20 1 Agaricus bitorquis 25-31 30 25-30 1 Agaricus blazei n.d. 30 20-25 1 Volvariella Volvacea 20-40 30-35 30-32 1,2 Tmg: The range at which the mycelium stays viable; the growth speed declines at both high and low ends of this range. Toptimal mg: The optimal temperature range for spawn run. Tfruiting: Temperature range required for fruiting. Substrate preparation techniques: 1 fermented and pasteurised substrate 2 pasteurised substrate

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3

Mushroom farms

Selecting a site When selecting a site to build a mushroom farm one has to keep in mind that following points are essential: ? availability of good quality substrate ? availability of clean water ? availability of labour ? adequate transport of the product to the market. Farm layout Before planning the layout it is essential to decide whether compost preparation will take place at the farm. If this is the case, keep in mind that storage of basic materials as well as the composting site itself should be located as far away as possible from the growing rooms.

It is equally important to know whether spawn will be purchased or prepared by the grower himself. In this case it is strongly advised that the spawn laboratory should not be located at the farm site at all, in order to prevent contamination spreading from one unit to another. Temperature and ventilation Growing rooms at a mushroom farm should provide adequate climatic conditions. In particular ventilation and temperature are essential to ensure a reasonable production. In most western countries, mushroom growers make use of mechanical climate control but this requires high financial investments and therefore will not be treated in this booklet.

To avoid high temperatures, more moderate temperature demanding mushrooms like Agaricus spp. are grown in caves or old tunnels. Or, the farm can be built at higher and thus cooler altitudes. As most low-cost growing houses are constructed from bamboo, wood and plastic, a simple way of obtaining temperature reduction is by spreading wet sand on the floors underneath the shelves in the grow-

Mushroom farms

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ing rooms and by wetting the bamboo-leave mats on the roof and the walls of the farmhouses. Floors Often, low cost growing houses are built just on bare ground. It is better to have a slightly tilted, cemented or concrete floor. These floors can be cleaned well and drain-water can flow out easily. Take good care that the drainage system of each room is not connected to another room, as diseases can spread easily through the draining pipe.

For the same reason it is wise to frequently collect waste and contaminated material and to have them destroyed immediately after collecting. Farm hygiene On a mushroom farm, hygiene is of vital importance. Since chemical control of pests and diseases is not feasible in small-scale mushroom cultivation, the only preventive measure is hygiene, and to some extent disinfection. This goes for a spawn production unit, the site for substrate production, the incubation rooms as well as for the production units. Farm location Therefore checking a suitable site for a mushroom farm is very important. The surroundings of a farm should be clean and free from possible contamination from insects, moulds etc. This means that building a new farm close to other mushroom farms should be avoided. Insects and diseases from these farms could easily spread to the new farm. If possible separate the various operation units of the farm.

The spawn laboratory should be separate from the growing site. The growing rooms ought to be separated by closed (plastic) walls to keep the different stages of cultivation apart. As a matter of fact no incubation or spawn running should take place in the same room where the mushrooms are harvested. 14

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Debris, contaminated bags and spent mushroom substrate must be removed immediately from the rooms and from the farm itself, preferably to a place far away.

All these measures are necessary to avoid pests such as flies and mites as well as diseases spreading from these waste dumps. If the spent mushroom substrate is to be used for gardening soil, it should be transported as soon as possible and not be stored at the mushroom farm.

Figure 5: An example of a sophisticated farmhouse unit/growing room with air lock and racks with shelves

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Figure 6: An example of a low-cost mushroom shed made from plastic with bags placed on the floor

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4

Spawn production

The mushroom propagation material (“seed”) is generally referred to as spawn.

4.1

Availability of spawn

The availability of good quality spawn is a limiting factor for mushroom cultivation in many developing countries. Customs’ bureaucracy, high shipping costs and the difficulty to keep the spawn cooled during transport, often hinders imports. It might therefore be necessary for the mushroom grower to produce his own spawn. If good quality spawn of the desired mushroom species can be obtained at a reasonable price, it would be wiser to concentrate on the mushroom growing process. If this is not the case, spawn will have to be produced or multiplied by the mushroom grower.

The complete procedure of spawn production involves preparation of the medium, filling the test tubes or Petri dishes and sterilising them, inoculation with mycelium and the process of inoculating larger containers with this culture Basically, spawn production is nothing more than putting mycelium of the desired mushroom in suitable sterilised substrates under aseptic conditions. In practice however producing spawn is not that simple. Suitable strains from the required mushroom species have to be maintained under strict conditions to avoid degeneration. If this is not possible, tissue culture from a fresh and healthy mushroom should be used for spawn production. In addition the total spawn production process requires very high standards of hygiene. It is for that reason that one has to make sure that the spawn production room is kept meticulously clean in order to avoid any contamination.

Spawn production

17


Figure 7: From tissue culture to crop - various steps in mushroom cultivation Spawn production of Agaricus spp. in particular, is rather complicated. From that point of view it is highly recommendable to buy spawn from a reliable spawn producer. Only in the case that good quality spawn is not available for a reasonable price the grower should choose to produce his own spawn.

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Spawn production unit The minimal requirements for a spawn production unit are: ? laboratory equipment such as Petri dishes, test tubes, scales, alcohol, flame ? sterilisation unit (pressure cooker, autoclave) ? sterile environment: Inoculation Box or Laminar Air Flow cabin ? incubation room

This equipment is commonly available in hospitals, research stations and universities. The raw materials include: ? ingredients for media preparation ? pure culture or fresh mushroom of the desired mushroom species strain ? spawn containers (such as bottles or plastic bags) In countries lacking mushroom production, spawn may be obtained from a renowned spawn producer, a university or a research station at the start of a project.

For addresses of spawn producers see Useful Addresses.

4.2

Clean environments

A clean environment is absolutely essential to spawn production. In particular whenever the containers with sterilised media need to be opened this must be done under aseptic conditions. The air carries numerous contaminants, which easily infect the sterilised media. It is therefore necessary to use special cabinets and inoculation rooms for performing the handling and the preparation of the (tissue) cultures. (For an air quality test see Appendix 2)

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Inoculation rooms The interior of the inoculation room should consist of nonbiodegradable materials. All the surfaces should be smooth and easy to clean. Shelves should be designed in such a way that the floor beneath can be cleaned easily. Shelves are typically made of metal or Formica. UV light, to be switched on during non-working hours, will help to destroy contaminants. Inoculation cabinets These simple inoculation cabinets are widely used all over the world. They can be constructed cheaply from locally available materials. The front glass pane can be opened to fill the cabinet with the sterilised media. The inside is to be disinfected by cleaning with a 10 % Clorox solution, a 2% Formalin solution or 70% ethyl alcohol.

Figure 8: A simple homemade inoculation cabinet showing a front glass pane that can be opened and holes (with cloth sleeves attached) for handling purposes

Take care when using chemicals. Some of them are poisonous and/or irritating to nose and eyes. Cautiously follow the instructions to ensure safe use.

Laminar Air Flow cabinets A Laminar Air Flow system (LAF) consists of a fan, a duct, a HEPA (High Efficiency Particle Air) filter and a hood. In a laminar airflow contaminants can spread in only one direction. In a turbulent airflow it is possible that spores move in different directions, thus causing more contamination.

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The ventilators are rated by the producers according to the volume of air they can blow through materials of specified resistance. About 0.45 m/s air velocity is considered best for good laminar airflow. The fan should be regulated stepwise and have the capacity to push double the amount of required air through the filter to reach the required air velocity, in order to account for pressure losses when the filter gets loaded with particles. In many countries neither HEPA filters nor the specific ventilators are available and have to be imported.

Figure 9: A Laminar Air Flow system (left) and cross section of the same LAF system (right)

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So keep in mind that a good inoculation cabinet is generally better than a poorly constructed and inadequately positioned LAF system. The filters and ventilators are the heart of any Laminar Air Flow system, but other factors have to be considered too: the operating persons, their skills and their hygiene, and the construction of the ducts and filters, to ensure that no contaminated air can be sucked in.

4.3

The sterilisation process

Grain, sawdust and compost contain large numbers of contaminants. A single grain kernel may contain millions of bacteria and fungi. Each one of these undesired agents, which are called contaminants, is capable of spoiling substrates that have not been properly sterilised or that have greasy appearance been inoculated under unhygienic conditions.

A heat treatment of 20 minutes at 121 째C is usually sufficient to kill all organisms. It takes quite some time for the steam to heat the inner core of substrates to this temperature, depending on the way the sterilisation / pasteurisation unit is filled and on the capacity of the burner. Pressure cookers (see figure 10) The cheapest option is to obtain one or more large pressure cookers. Select pressure cookers that maintain the pressure when the final temperature has been reached.

The simplest pressure cookers blow out steam when the pressure is too high. The pressure inside will then often drop below 1 atmosphere overpressure, causing the media to boil.

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Figure 10: Cross-section of a pressure cooker for use on a burner (left) and an electric pressure cooker or simple autoclave (right)

4.4

Preparation of media

Most species grow on the following media: Potato Dextrose Agar (PDA) extract medium (see figure 11) Ingredients: 200g diced potato, 20 g agar powder, 20g dextrose or ordinary white sugar, 1 litre of water.

? ? ? ? ?

Wash and weigh the potatoes and cut them into small pieces. Boil for about 15 to 20 minutes until they are soft. Remove the potatoes. Add water to the broth to make exactly 1 litre. Add the dextrose and the agar. Be sure to add the right amount of sugar and agar, otherwise the medium will become either too soft or too hard. ? Stir occasionally and heat gently until the agar has melted. The agar should be hot when poured into the test tubes or bottles otherwise it will become lumpy. ? Fill about one fourth of the test tubes. ? Then seal the tubes or bottles with cotton plugs.

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4.5

Preparation of slants

After filling the test tubes or bottles with the medium (see figure 11, picture 5), they must be sterilised (see figure 11, picture 6) before they can be used. The most commonly used sterilisation units in smallscale laboratories are pressure cookers, but autoclaves can be used as well. Procedure ? Pour water into the pressure cooker to the level of the rack. ? Place the bottles/test tubes in the racks with a plastic covering to prevent water from wetting the cotton plugs. ? Then close the lid firmly. ? At the beginning of the process the air vent should be open in order to allow the air to escape. Some minutes will pass between the moment of boiling and steam escape. ? Close the air vent. A pressure gauge shows the pressure rise. ? Sterilise under pressure for 20-30 minutes. ? Do not open the air vent before the pressure cooker has cooled down completely to room temperature! ? Open the pressure cooker and take out the test tubes or bottles. To increase the surface area, the test tubes are placed in an inclined position (e.g. on a ruler or a rolled towel) when the agar is still fluid. Take care that the agar does not touch the cotton plug, in order to prevent contamination.

Do not move or handle the test tubes until the agar has solidified to prevent that a small portion of the agar should solidify at the other side of the slant or too close to the plug.

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Figure 11: Preparation of Potato Dextrose Agar (PDA) extract medium (pictures 1- 4). Filling (picture 5) and sterilising the slants in a pressure cooker (picture 6). Spawn production

25


4.6

Cultures

The first steps in spawn production are performed on artificial media. These should contain sufficient nutrients for the mushrooms to grow, like saccharides and a solidifying agent (agar or gelatine). The mycelium grows on the surface of the medium and will later be used to inoculate larger amounts of grain substrate. Test tubes or Petri dishes (or flat whiskey bottles) are used as culture containers. Instead of working with cultures, one could also try to purchase small amounts of good quality mother spawn to prepare the final spawn.

4.7

The starter culture

See figure 12: 1 The starter culture (or mother culture) can be obtained from a spawn producer or laboratory or made from a fresh and healthy fruiting body. 2 More agar cultures are then made from this starter culture. 3 More test tubes are inoculated using the methods described for culture transfer (see Appendix 4 for detailed instructions). 4 These serve to inoculate larger containers (like bags or bottles) with mother spawn that can be used to inoculate the final spawn substrate. The mycelium will degenerate after a certain number of transfers, so it is not possible to keep on transferring the cultures on agar forever. To prevent the spawn culture from degenerating stick to the following rules: ? Never transfer from one mother culture more than eight times. ? Neither use mother cultures on agar for longer than two years.

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Figure 12: Multiplication of cultures (see section 4.7)

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4.8

Tissue cultures

(See figure 13.) Only in the case that the starter culture cannot be purchased from a spawn producer or a laboratory, the mother culture should be produced from tissue cultures

Young and vigorous mycelium can be obtained from a young fruiting body using a scalpel, alcohol, sterilised agar slants, Petri dishes or bottles with agar, flame (non-smoking), and a clean table to work on, or preferably a Laminar Air Flow cabinet or inoculation box. ? ? ? ? ? ? ? ? ?

Wash the mushroom thoroughly. Dip the scalpel in alcohol, and then flame it until red-hot. Let it cool down for 10 seconds. Now break or tear the mushroom lengthwise (do not cut it with a knife, since contaminants from the surface can stick to the blade). Do not touch the inner surface with your hands. Use the heated scalpel to remove a small piece (2x2 mm is sufficient) of the inner tissue. Take care that no outside surface tissue is included. Open the test tube/Petri dish. (When using test tubes: heat the mouth of the tube in the flame to kill unwanted spores). Then gently replace the tissue on the scalpel in the middle of the agar. Immediately replace the plug. Inoculate at least three cultures, but preferably more.

Incubate the newly inoculated agar slants or Petri dishes at 25 째C for about ten days. Within three to four days mycelium will cover the tissue and branch out on the agar. If no growth occurs on the agar, check the following: ? Possibly the mushroom was too old. Try a fresher specimen. ? Possibly the scalpel did not cool down before taking the tissue sample, thereby overheating and thus killing the mycelium.

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Figure 13: Preparation of the starter culture or mother culture from tissue The mycelium should be white. If yellow, blue, green or grey mycelia form on other places on the surface, then these are fungal contaminants. A creamy, shiny growth often indicates bacterial contamination. (See appendix 3: Different origins of contamination)

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4.9

Mother spawn

Mother spawn can be used to inoculate either grain spawn or a second generation of mother spawn. In simple laboratories, mother spawn should not be used to inoculate another generation of mother spawn because of the high risk of contamination

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Shake the bottles when taking them out of the autoclave or the pressure cooker.

Figure 14: (Pictures 1-5) Preparation of grain spawn in glass bottles. The mouth of the bottle is to be cleaned (3) to prevent spores from germinating. (Pictures 6 – 14) Culture transfer /inoculation of the glass container with mother spawn. (Pictures 14-16). Incubation of the spawn. Magnified detail: The mycelium is growing all over the substrate in the bottle. Preparation of grain spawn (see figure 14) For Agaricus spp. and Volvariella spp. only grain spawn is used. The main advantage of grain is that it is very nutritious for fungi and forms kernels easily. The kernels can easily be dispersed in the substrate. The main disadvantage is that it provides an optimal substrate for other organisms too. The chances of contamination are therefore high. Spawn production

31


Kinds of grain Different grains can be used such as wheat, rye, millet, rice or sorghum. First boil the grain, then drain, fill containers and sterilise. The moisture content of the grain, after boiling, should be around 50%. If it is higher, mycelial growth may be faster, but the danger of wet spot bacteria is also greater. If it is drier than 35% mycelial growth will be rather slow. Grain spawn formula 1 Grain in small containers can be moistened to a higher degree than grain in 15 litre bags. For 2 litre containers, use the following recipe: 480 g rye, sorghum or wheat, 400 ml water, 2 g gypsum (45% moisture). (See Appendix 1) Grain spawn formula 2 Grain spawn substrate: grain 10 kg, CaCo3 147.5 g, Rice bran 1.25 g, Gypsum 0.1475g, Urea 0.5 g, Water 1.5 litres. (See Appendix 1) Sterilisation Sterilise the spawn containers in an autoclave. The length of time depends on the autoclave, the way the spawn containers are packed (dense or loose) and the size of the containers. For instance, two hours for 500 g containers; three to four hours for 3-kg bags. The spawn containers should be properly cooled down before taking them out of the autoclave. Steaming in an oil drum for at least 6 hours is usually necessary to ensure proper heating of the inner core of the substrate bags. Sterilise 4-litre bags filled with 2kg spawn substrate for at least 2 hours at 121째C.

Inoculation (see figure 14, pictures 6-14) Once the temperature in the centre of the container has reached the optimum mycelial growth temperature, the spawn containers can be inoculated. Use at least one square of 10 x 10 mm (for 250 ml bottles) or two squares of 10 x 10 mm (for bigger bottles) from the full-grown agar of the mother culture for each bottle.

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Incubation Incubate the bottles until the mycelium has grown all over the substrate. The temperature should be close to the optimal temperature for mycelial growth. (Consult Table 1). Shake once (after eight days) or twice during the incubation period (or every three or four days) to distribute the mycelium evenly and to prevent kernels from sticking together.

Storage Keep the spawn in the refrigerator and only take it out when needed. At temperatures above 25 째C grain spawn can spoil in one night.

Storage and purity Good spawn shows vigorous mycelial growth and contains no other organisms. If stored too long it will become less vigorous.

4.10 Preparation of the final spawn In order to inoculate the compost on the shelves (or the compost in the cultivation bags on the floor) larger quantities of spawn are used; generally referred to as final spawn. In order to prepare the final spawn, plastic bags can be used as spawn containers. The procedure for final spawn is similar to that of mother Figure 15: Sterilising large spawn. Only the sizes of the contain- spawn containers in an oil drum ers differ. See figures 15 and 16.

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Figure 16: Once the mycelium is full grown (see magnified detail) the content of the bags is ready to spawn the compost in the beds

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5

Composting

In nature saprophytic mushrooms are able to obtain their nutrients from plant residues and dead wood. Cultivated mushrooms such as the Agaricus spp. (Button Mushrooms) and the Volvariella spp. (Rice Straw Mushrooms) can only grow on fermented or composted plant residues. The process of fermenting is called composting. Composting is necessary in order to make the dead organic materials suitable for these mushrooms to grow on. Thus composting is essential for obtaining: ? a selective nutrient medium (i.e. a nutrient medium that is highly suitable for the mushroom mycelium we want to grow and less suitable for all kind of competing moulds). ? a homogeneous nutrient medium with a homogeneous structure and constant moisture content. Materials Farm waste such as wheat straw, rice straw or pressed sugar- cane (bagasse) is generally used as basic organic material for composting. Check which sources are available in the region and make sure that there is a constant supply of good quality basic materials. Good quality straw means: the straw is dry and not rotten. To ensure a good mixing the straw should not be stacked in bundles or bales, but should be cut to a size of about half a meter. Structure of the straw While most wheat straw has a good structure, rice straw easily clogs up and congests when it remains too wet. Moreover, if the straw particles are too short, air will not pass through easily. For similar reasons hay from dried grasses is less suitable; as soon as the materials are wet they will form clumps and block the airflow inside the heap. Mixing is the most important part of compost preparation. Most of the complaints about poor compost are related to poor mixing.

Composting

35


In the case of bagasse, it is important that it ages in the open field before usage, so that sugar residues will leach out by rain, thus preventing harmful fungi, which feed on these sugars, from growing.

Figure 17: Stacking and turning the compost heap. Temperature in the compost heap should not exceed 55째C. to prevent loss of valuable nutrients.

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Manure As a protein source, mostly straw-rich stable manure of animals is used. Usually, horse manure or chicken manure is used but the manure of other animals can also be employed. Poultry manures tend to have a higher nutrient content than horse or cow manure and is often further concentrated through drying.

If manure is scarce or not available at all, artificial manure such as urea can be used as well. Besides manure, gypsum or chalk is added. Moreover, like in all bacteria and fungi-induced processes water is needed during composting. Last but not least, once the materials are piled up, aeration of the heap of organic materials is an important procedure. Aeration is vital to ensure a proper decomposition and to avoid unwanted anaerobic and smelly processes. It is for this reason that the organic material should have a good structure. Neither should it be too compact when piled up. Recipe 1 1000 kg of straw-rich stable manure or straw mixed with chicken manure, thoroughly mixed with 10 kg of chalk. Water is added until it leaks out of the pile. Recipe 2 (to be used if no manure is available) See appendix 5 1000 kg straw 10 kg urea 20 kg ammonium sulphate 8 kg potassium sulphate 25 kg calcium carbonate

Location of the compost site When selecting a location for composting, one has to keep in mind that the site should not be in the proximity of houses, to avoid complaints about smell. The composting site should also be located at a certain distance from the growing rooms and the laboratory.

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37


If storage of basic materials and composting takes place close to growing rooms, pests and diseases can easily spread towards these growing rooms. Although it will cost more labour and effort to move the compost into the growing rooms, the result will be an improvement of farm hygiene. This extra effort for transportation is minor compared to the risks, costs and losses that come with a heavy crop infestation caused by neglecting the basic rules of farm hygiene. Composting preferably should be done on a concrete slab. If possible the concrete slab should be constructed with a slight tilt, with a cemented basin at the bottom end to collect the water leaking from the compost. This run-off water (or goody water) can be reused for watering the compost.

Dimensions and form of the pile The materials are piled up in compost heaps (see figure 17) that have standard dimensions; they do not exceed a height of 1.5 m and are straight sided. In mushroom cultivation these dimensions have proved to be most efficient and to guarantee a proper decomposition of the used materials. Roofing Above the concrete slab some roofing is recommendable in order to prevent that the compost heap dries out by sunlight or gets soaked by heavy rains. Composting process Composting is a process of decay caused by microorganisms, which results in a selective and nutrient-rich substrate suitable for the mushroom we intend to grow.

Standards that are essential for a successful compost preparation are indicated below.

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Watering and prewetting The dry organic material is piled up on a heap and wetted with water. The heap has to be kept moist but not soaked, so that soluble nutrients will not leach away.

This prewetting stage will take about 5-6 days and every day some more water is added. The practice of wetting should soften the outer layer of the straw by decomposing its wax layer. Some times prewetting is performed by soaking straw for a few days in a water basin. Aeration After the prewetting stage the straw and manure are thoroughly mixed and stacked into a pile with a height of 1.5 meter. The inner part of the pile should not be too dense in order to enable a good aeration.

Composting is a biological process that generates heat. When composting is performed properly, temperatures may rise to 60 ËšC. A good compost pile will produce some steam. A simple method to check the temperature of the pile consists in putting a hand into the pile. You will be able to stand a temperature Figure 18: Checking of 55 ËšC, so when the temperature is higher the temperature in you are forced to quickly withdraw your the compost pile hand. A well maintained compost pile produces hardly any bad odours, but will produce some steam.

When a lot of vapour escapes from the compost pile and temperature exceeds 60/70 ËšC, the compost is too hot. In that case it is wise to lower the temperature by turning the heap inside out.

Composting

39


Mixing and Turning The rate of decay is accelerated by turning and mixing the pile at intervals. Although proper mixing is extremely important, this aspect of composting is often undervalued. In order to achieve a successful composting process it is essential that the materials are thoroughly mixed before piling them up!

Frequent turning of the heap is required in order to ? ensure a quick and proper decomposition ? prevent the compost pile from overheating ? obtain a homogeneous structure. At the first turning add gypsum and also make sure that manure lumps are broken and the compost is thoroughly mixed Basic turning schedule A basic schedule includes turning the pile after 5 days and consequently another 4 times every 3 days. Make sure that during turning of the heap the outer layer of the compost will end up on the inner side of the new heap and vice versa. Moisture Biological processes, such as composting, need water. During the entire process the compost should be kept moist but not wet to the extent that water is leaking out. On the other hand, when the compost is too dry, water should be added to get an optimal process. In case rice straw is used, special attention should be paid to the applied amount of water, in order to prevent clumps of compost, which will block the airflow in the heap.

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Figure 19: Squeeze test. Squeezing a fistful of compost, only a few drops of moisture should appear between the fingers. In that case, the moisture content is approximately 60 %

Once the compost is ready, it is to be transported either to the shelves in the growing rooms or to fill the plastic growing bags or other containers. In many regions, groups of mushroom farmers jointly prepare compost at a central location. From this location the compost is then transported to the individual farms.

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6

Cultivation of Button Mushrooms (Agaricus spp.)

Most cultivated Button Mushrooms belong to the species Agaricus bisporus. This species is rather difficult to grow under primitive circumstances. Therefore small-scale mushroom growers are advised to grow locally available Agaricus varieties.

6.1

Pasteurisation or peak heating

Fresh compost is not immediately suitable for mushrooms. It requires further treatment. Therefore, fresh compost has to be transported to the growing house and placed on the shelves or brought into a tunnel for the next phase. This phase is called peak heating or pasteurisation. Peak heating is necessary in order to destroy unwanted organisms and microorganisms, such as flies, bacteria and green moulds. The optimal compost temperature for pasteurisation is 60 째C and should be maintained for at least 8 hours. Steam is used to heat up the rooms. A simple method to generate steam is through heating water in oil drums and leading the steam through a hose into the growing room or the tunnel. (See also appendix 6: Simple steaming systems)

Figure 20: Steam producer made from oil drums

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The pasteurisation or peak heating procedure is followed by the conditioning phase in order to prepare the substrate for spawning. Conditioning implies gradually lowering the temperature within 1 or 2 days and is necessary to get rid of the free ammonia in the compost. Spawning cannot take place at temperatures above 30 째C. Actinomycetes During the period between peak heating and spawning, white fungal spots caused by Actinomycetes will develop in the compost. These fungi will not inhibit the mycelial growth of the mushrooms. Some people appear to be allergic to Actinomycetes. These persons should not be involved in, or carry out the spawning procedure.

6.2

Spawning

When the temperature has dropped sufficiently (preferably below 30 째C), spawn has to be added and mixed through the compost. This process is called spawning. Button Mushroom growers generally use about 6-8 litres of spawn per 1000 kg (1 tonne) of pasteurised compost. The spawn has to be mixed homogeneously through the compost layer. Mycelium growth After spawning the mycelium will start to develop. The optimal temperature for mycelial growth is about 25 - 27 째 C. Sufficient moisture is another important factor for mycelial growth. As a consequence the Relative Humidity should be very high (RH 95% or higher)

To achieve such a high RH, several measures are to be taken: The compost on the shelves or in the bags should be covered with sheets of non-printed newspaper. The paper sheets are to be sprayed regularly, as well as the walls and floors. In general, it takes 2 weeks before the compost layer will be sufficiently colonised by the mycelium. At this stage the compost is referred to as full-grown compost.

Cultivation of Button Mushrooms (Agaricus spp.)

43


In literature supplementation (adding high-protein nutrients to the compost) is often mentioned with regard to boosting yield levels. However, if adequate cooling of the growing rooms is not feasible, supplementation will have an adverse effect on the yield. Overheated compost will not produce any mushrooms at all. As a consequence, supplementation should be performed exclusively on more sophisticated farms with cooling units.

6.3

Casing

The compost layers are now full-grown with mycelium, but they will not produce a good mushroom crop yet. Therefore, the Button Mushrooms need a layer of casing soil. The casing soil will provide the right bacteria and the right amount of water, stimulating the mycelium to form a good crop. Watering directly on the compost would cause rot and, consequently, no mushrooms would develop. The casing soil will also serve as a water buffer. Formula 1 Course peat Limestone

4 parts 1 part

Formula 2 Loamy soil and coconut fibre mixture Casing soil can be made from peat. If peat is not available, a good alternative would be the use of soil without parasites, dug from at least 50 cm deep.

The casing soil is applied on top of the full-grown compost in a layer up to 5 cm thick. To check the water-holding capacity of the casing soil; ? Put a layer of 5 cm thick on a frame covered with an insect screen. ? Irrigate in the same way as in the growing room.

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? The moment water passes through the screen, the soil’s water holding capacity will have been reached.

Figure 21: Water holding capacity check Beware of spraying too much water on the casing soil, in order to prevent water from seeping through the casing soil towards the compost and causing rot!

Ruffling the casing soil When the mycelium has grown well through the casing soil, the procedure of ruffling can start. Ruffling implies that the mycelium is mixed by lightly raking the casing soil layer, to get a more uniform mycelium growth. The ruffling procedure will break the mycelium in the casing soil layer, stimulating regrowth. Cooling down and formation of fruiting bodies When the mycelium has a fluffy white appearance and has grown well into the upper layer of the casing soil, cooling down can start. This measure is taken in order to trigger the change from vegetative growth (mycelium) to generative growth (fruiting bodies). This climate change can be achieved by increasing the air ventilation. If possible the compost temperature should be reduced with about 5-6 ° C to approximately 20 °C, within a few days. Each strain has it own requirements. If a temperature reduction is hardly feasible, mushrooms may

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develop but the yields will be low. Be aware that modern Agaricus varieties require a strict cooling down. Spraying water and Relative Humidity (RH) As soon as the mycelium stops growing, the mycelium threads start to form clusters and form little pinheads. Since the pinheads are very sensitive to dehydration, a high RH is required. As soon as the fruiting bodies are pea size, spraying water can start. The amount of water used depends on the speed of growth, the expected yield and the way of harvesting. By rule of thumb 1 litre of water is sprayed for each kilo of mushrooms to be harvested.

Spraying can be carried out either before or after harvesting. Make sure, however, that the mushroom caps are dry within one hour. Otherwise bacterial blotch will develop on the mushrooms.

This bacterial blotch is also triggered by insufficient ventilation and by weak mushrooms.

6.4

Harvesting and picking

In general the first mushrooms can be harvested approximately 3 weeks after casing. The mushrooms are picked manually according to their required size. This size will differ according to the customer’s requirements: some customers like small closed Button Mushrooms, while others prefer large open ones (‘flats’). Each individual mushroom is removed from the casing soil, pulling it carefully by the cap with a light rotating movement. Depending on the mushroom size, two, three or four specimens can be picked in one hand. The sandy stumps are cut away from the stems and the mushrooms are graded and packaged according to their required quality. Picking of the mushrooms should be done with clean hands and bruising of the caps should be avoided.

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The mushroom harvesting period will last several weeks, depending on the growing schedule and compost quality At the end of the harvesting period, the compost in the growing rooms has to be steamed again (`cooking out’) in order to destroy the mycelium and more importantly to exterminate any adverse organisms. Afterwards, the spent mushroom substrate (SMS) can be used to improve garden soil.

6.5

Case description Button Mushrooms

In the Chiang Mai region, Northern Thailand, some farmers grow Agaricus spp. (Button Mushrooms) during the cool season. Ingredients For compost preparation, rice straw is used and mixed with urea and gypsum. Rice straw is abundantly available in the region. Recipe: 100 kg rice straw 5 kg urea 2-3 kg Super phosphate.

The rice straw is cut in pieces of about 75 cm, wetted for 2 days in concrete basins and mixed thoroughly with the other ingredients. Then the straw mixture is piled up in heaps of about 1.5 meter high using a metal frame to ensure that the compost heaps are neatly packed and straight sided. Turning and mixing Turning of the compost is done every 2 days. After one week the compost is ready and transported into the growing house on shelves in a layer of 15 cm thick (about 80 kg/m²). Temperature treatment and conditioning The compost is pasteurised with steam for 6 hours. After cooling down and conditioning the compost is spawned.

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Figure 22: Steaming of the growing room/compost in the beds Spawning the substrate Grain spawn is purchased from distributors or is produced by the growers themselves using mother cultures purchased from laboratories. The spawn rates are variable and range from 3-7 litre per tonne of compost. Casing After the spawn run is complete, a 5 cm layer of casing soil is applied, using red sandy loam and some coconut fibre. 48

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Construction of the mushroom house The growing rooms are similar to the ones used for the cultivation of rice straw mushrooms. They are constructed from bamboo and have plastic linings. The roofs are generally double layered with bamboo leaf mats at the outer sides. Temperature control Wetting these leaf mats by water sprinklers induces evaporation and therefore will lower temperatures in the growing room. By sprinkling the floors with wet sand another temperature drop of approximately 5 째C is achieved. No further ventilation or climate control is available. Harvesting and marketing Harvesting is done daily. After the mushrooms have been brought to the collecting place, the stems are trimmed. Yields obtained are approximately 80 kg per ton compost.

The Button Mushrooms are sold fresh to individual customers on the nearby markets or are sold through a middleman to the canning industry.

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7

Cultivation of Rice Straw Mushrooms (Volvariella spp.)

In cultivation of Rice Straw Mushroom (Volvariella spp.) two methods are employed: indoor cultivation and traditional outdoor cultivation. Outdoor cultivation In several Asian countries farmers grow Rice Straw Mushrooms in a corner of their fields, after harvesting the rice crops and before starting the new rice-growing season. This outdoor cultivation hardly requires any investments other than labour. However, yields are generally very low, due to pests and diseases. Therefore, this method will not be elaborated in this booklet Indoor cultivation Indoor cultivation requires investments but it will produce a more reliable yield. Loans can of- Figure 23: Different stages of ten be obtained from companies or Volvariella spp.; from tiny butmicro-credit organisations, in or- ton to mushroom. Full growth der to start a farm. Rice Straw of the mushroom takes only Mushrooms grow rather quickly, three to four days compared to other mushrooms such as e.g. Button Mushrooms. This guarantees a fast return on investments. Volvariella mainly utilises cellulose as a nutrient and therefore higher yields are obtained from substrates with high cellulose content. For that reason cotton waste usually is mixed with rice straw.

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Requirements for indoor cultivation: ? plastic mushroom shed with shelves or an industrial building (with water resistant and heat resistant walls) ? concrete floor for composting phase ? steam boiler ? forks for composting, filling the shelves and spawning. ? spawn ? basic materials for composting such as rice straw, cotton waste, etc and a good water supply. Formula 1 rice straw cotton waste rice bran lime Formula 2 dry cotton waste rice bran limestone (pH regulator)

45% 40% 10% 5%

90-92% 4% 4-6%

See Appendix 5 for more substrate formulas. Substrate preparation The dry materials have to be moistened thoroughly, for instance by soaking them in water. Cotton waste may get completely saturated with water, thus preventing the access of air. It should therefore always be mixed with another material, such as rice straw, to ensure sufficient aeration. Use the squeeze test to determine whether the substrate materials have absorbed sufficient or excessive amounts of water.

Then form piles of at least 1.5 m3 and cover them with plastic to avoid loss of water and energy; evaporation consumes large amounts of energy.

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The heaps should be turned once or twice within a total period of two to four days in order to prevent long-term anaerobic conditions in the heap. Add rice bran or another supplement during the last turning of the heap. Since the supplements provide easily degradable nutrients for microorganisms, the temperature of the substrate will increase.

Figure 24: Cross-section of a growing room with compost beds on shelves. The room can be steamed with the oil tank steam producer (right). Peak heating The substrate is now ready for heat treatment. Beds in the growing room are filled with a substrate layer of 10 to 15 cm thick (about 50 kg wet substrate per m2, i.e. approximately 15 kg of dry substrate material per m2). Steam is blown into the growing room until the substrate (not the air!) has reached a temperature of 60 째C. The steam inlet is adjusted to stabilise the substrate temperature for about three to four hours.

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Actinomycetes During the period between peak heating and spawning white fungal spots, caused by Actinomycetes, will develop in the compost. These fungi will not inhibit the mycelial growth of the mushrooms. Spawning Spawning occurs as soon as the temperature drops below 37 째C. Spawning rates differ among producers, depending on the vigour of the strain involved. Usually about 1% is used, with upper and lower ranges of 0.5% and 5% (w/w). Volvariella spp. grows very fast, so 1% is often sufficient.

Different spawning techniques and spawn substrate materials may be used. Some growers use a short fork to mix the spawn evenly with the substrate, while others make holes with a wooden dibble and insert peanut-sized pieces of spawn, at 12 to 15 cm intervals, at a depth of 2 to 2.5 cm. Some people appear to be allergic to Actinomycetes. These persons should not be involved in, or carry out the spawning procedure.

Spawn run Cover the substrate with plastic to keep the temperature high (35 째C) but not above 40 째C. Volvariella will colonise the substrate in only a few days. Remove the plastic after three days and ventilate some more after six days. Light Light is also needed for the formation of fruiting bodies. Use white light or make sure some daylight can reach the substrate as from three days after spawning. Just a little light is sufficient; 15 minutes of sunlight or a day/night cycle of 500 lux have been reported to be sufficient. When one can read a newspaper inside the growing room, the supply of light is sufficient.

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Humidity Spray a fine water mist to maintain optimum humidity and take care that direct watering does not damage the delicate mycelium. Harvesting and Picking Although this may require two or three pickings per day, the mushrooms should be picked while still young, i.e. when they are in egg stage and the cap has not ruptured the veil yet. Opened ones are difficult to sell, because they have to be consumed the same day. Be careful not to bruise the mushrooms while picking them.

The production level is acceptable when the mushroom yield (fresh weight) equals 25% or more of the dry weight of the compost. Since straw mushrooms can be grown very quickly, a relatively high output can be reached per growing period, although their yield is significantly lower than that of other mushrooms. At the end of the harvesting period the compost in the growing rooms have to be steamed again (`cooking out’) in order to destroy the mycelium and, more importantly, to exterminate any adverse organisms. Spent Mushroom Substrate After cultivation the spent mushroom compost (SMS) can be used to improve garden soil. In some countries the spent compost of Button Mushrooms is used to grow a crop of Rice Straw Mushrooms. The beds with the old compost are emptied and the house is cleaned. Cotton waste is mixed with the old compost and fermented for some days. Then a heat treatment is applied. Seven to nine days after spawning, the first pinheads appear. Usually two flushes are harvested.

7.1

Case description Rice Straw Mushroom cultivation

In the Karawang Region East of Jakarta, Indonesia, many small farmers grow Rice Straw Mushrooms on low investment small-scale farms. Rice Straw Mushrooms, Volvariella spp., are suitable for cultivation in warm climates.

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Quite some villages in this predominantly rice growing region have clusters of small mushroom growers. Each grower owns one (sometimes more than one) simple mushroom growing house, made from bamboo with a plastic lining at the inside. Since the Karawang Region is actually a rice-growing region, rice straw is abundantly available but is considered an agricultural waste and just left on the field. Compost The major basic material for compost production is rice straw The other ingredients are: ? chicken manure or urea ? cotton waste ? rice bran and ? gypsum. Composting process After thoroughly mixing and wetting, the materials are piled on heaps with a height of about 1.5 meter. In general, the heaps have some sort of cover to protect against excessive climate conditions and prevent drying out by the sun or soaking by rain.

Temperatures in the heaps rise up to 60 C째 and in general the heaps are turned every 2 days to avoid overheating of the compost. In general, the compost will be ready in 6-8 days. Filling the beds The compost is transferred and put in 20 cm thick layers in the shelves in the growing house. The compost layers in the shelves are covered with a thin layer of coconut fibres. Sometimes, the coconut fibres are mixed with some cottonseed waste. Growing houses Each growing house has 2 rows of 5 shelves high. The distances between the shelves vary, as well as the thickness of the compost layer, in order to ensure that the temperature will be the same in all layers.

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The inner side of the growing house is enclosed with plastic. The costs of a growing house are about € 150 - € 200 for materials.

Figure 25: Harvesting from bamboo racks Pasteurisation Subsequently the compost in the growing house is pasteurised for 6-8 hours at about 60 C°. Pasteurisation is done by steam produced through heating oil drums filled with water. The steam is led into the growing room by a rubber hose.

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Spawning After pasteurisation and cooling down of the compost, the substrate is spawned. The spawn run will take 7-10 days. Spawn is generally bought from spawn distributors, who obtain it from larger laboratories. In this region the Volvariella species used is suitable for these high (33 ËšC) temperatures.

When the spawn run is complete, more air and light is let into the growing room to induce fructification. Harvesting will take place 2 times a day, over a period of 2-3 weeks. The yearly production of an average growing house with a surface of about 100 m2 is approximately 200,000 kg. Marketing Marketing is performed by farmer groups or through middlemen. The mushrooms are sold on the various markets of Jakarta, where Rice Straw Mushrooms are in demand. The average grower will have an income of about â‚Ź 1,500. In general some of these revenues are used for school fees or for medical bills.

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8

Harvesting and post harvest handling

Edible mushrooms are a delicate product with a short shelf life. Most of the time mushrooms are marketed fresh but they can also be preserved. This chapter pays attention to: ? harvesting ? how to handle mushrooms for the fresh market ? preservation.

8.1

Harvesting

Button mushrooms as well as Rice Straw Mushrooms should be picked at the stage at which they have the highest profitability that is when the cap is still closed. When picking mushrooms, take care to gently break them from the substrate or casing soil. Avoid tearing away chunks of mycelium from the substrate/casing soil. The welldeveloped specimens have to be picked very carefully from mushroom clusters in order to leave the small ones to continue growing. Since mushrooms can easily be damaged, it is best if handling is kept to a minimum. Immediate trimming and grading, when picking, and packaging them in the packages in which they will be sold, ensures that they are touched only once: at the moment of picking. After picking, mushrooms should be kept as cool as possible. If no cooling facilities are available, then put them in a shady place. When placed on a wet concrete slab and covered with a wet cloth, the boxes with picked mushrooms will keep cool for several hours. Make sure that the wet cloth does not touch the mushrooms!

8.2

Fresh market

Under ideal conditions, mushrooms for the fresh market are cooled rapidly after harvesting and then packaged with a plastic film. The plastic film provides good protection from water loss, as long as the 58

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storage temperature is more or less constant. Repeated exposure to fluctuating temperatures should be avoided. When the temperature goes up, the mushrooms will lose water. When the temperature drops, water will condense inside the package and on the surface of the mushrooms. This will lead to fast wilting. Make sure that the mushrooms are cooled down before wrapping or covering them in plastic in order to avoid condensation within the package.

8.3

Preservation

Preservation of mushrooms is necessary only when harvested mushrooms cannot be sold fresh. There are many different preservation methods but for small farms many of these methods, including the commonly used canning method, are too complicated and the equipment is too expensive. Therefore, they will not be described here. The simplest method is cooking the mushrooms in water in order to stop growth and enzymatic processes. Take the mushrooms out of the cooking water, cool them down and package them together with the cooking liquid in plastic bags, which are to be sealed immediately afterwards. This method is used quite often for Rice Straw Mushrooms. Mushrooms treated in this way will keep for 1-2 days. Another method is blanching the mushrooms by cooking them for 10 minutes in water at a temperature of 90Ëš C (preferably 1 kg of mushrooms in 5 litres of water). Cool them down after blanching. When mushrooms appear floating on the surface they have not been blanched sufficiently. After cooling down, put the blanched mushrooms in twist-cap glass jars and fill up with a watery solution of 2% salt and 0.2 % citric acid. Heat the closed jars for about an hour. This product will keep for weeks. For both methods it is necessary that the procedure be performed in a clean and hygienic way in order to avoid problems of contamination and to assure good quality.

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8.4

Drying

Drying has several advantages: it is easy, quick and safe and welldried mushrooms can be stored for a long time. Besides Agaricus spp. and Volvariella spp., many other cultivated and also wild mushrooms are commonly sold dried. Drying by sun In tropical areas, many edible products are displayed on racks to dry in the sun. The sun warms up the products as well as the surrounding air, causing evaporation of the products’ water content. Besides drying on racks, the drying procedure can be performed in simple constructions, known as sun driers. A sun dryer can function in a direct or indirect way. Direct sun dryer A direct sun dryer (figure 26) is not expensive and is easy to handle. A disadvantage is that it allows hardly any control of the temperature; neither is the product protected against external influences. Indirect sun dryer With an indirect sun dryer (figure 27) temperature can be controlled better. And as the product is not exposed to UV light, fading will not occur. During the drying process the following rules should be observed: ? The mushrooms should not touch each other. ? Air circulation is very important; put the mushrooms on a grill rack or a metal grid. ? Since the freshest mushrooms lose much water through evaporation, they should be put on the lowest tray.

Mushrooms do not have to be crisp to the touch after drying; they should still be slightly flexible. The quality of sun-dried mushrooms is generally less than that of artificially dried ones. The moisture content of sun-dried mushrooms is higher and therefore they can be kept for a shorter period than the artificially dried ones.

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Figure 26: Direct sun dryer and cross section of the same dryer

Figure 27: Indirect sun dryer and cross section of the same dryer

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Packaging and storage All foreign material should be removed at the end of the drying process. Dried products easily absorb water from the surrounding air because of their low water content, so packaging has to take place in a dry room.

It is a good idea to finish drying during the warmest part of the day when the relative humidity is at its lowest. The product can be cooled in the shade and if the work is done hygienically, the cooled products can be packaged immediately. The packing material must be waterproof, airtight and insect-proof. The dried products will only remain good if stored in such a way that they are dry and protected from insects. Normal plastic bags (properly sealed) will do for some time, but are not entirely gas and waterproof. It is also possible to use polymer-coated cellophane bags, which are waterproof and airtight. These can be sealed with a hot iron or a sealing machine (where electricity is available). Unfortunately this kind of plastic cannot be easily obtained and is not too strong either. A plastic bag of thicker quality (polyethylene, 0.05 mm thick) is best. These can be closed tightly with a metal clip or with cellophane tape. From a marketing point of view it is recommendable to include a sticker describing the product and a recipe.

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9

Marketing

Marketing is a vital aspect of developing a healthy business. Marketing includes products, prices, physical distribution and promotion. Although small-scale farmers have limited possibilities to deal with these topics, the topics are often discussed vividly. One should know to whom and in which places one will sell one’s product as soon as, or even before, building a mushroom farm, be it a simple barn or a more sophisticated construction.

Figure 28: Selling mushrooms on the marketplace

Marketing

63


That means that one will have to explore in advance who the customers are and where to find them. For instance: ? Marketplaces ? Delivery to door ? Tourist centres and hotels ? Shops and/or supermarkets Specific demands One should realise that each customer group has specific demands with regard to products, prices and delivery. Supermarkets The past few years the percentage of households that buy mushrooms at the local market and at the greengrocer’s has diminished. In Western Europe and the USA, supermarkets play a predominant role as sales channels for mushrooms. Most households (90%) buy at supermarkets; a trend that is likely to develop similarly in parts of Africa and Asia. This means that presentation of the product and proper packaging become increasingly more important Market and market channel Small-scale growers should focus on the local markets. Export markets are far too complicated, even when they join forces and cooperate with each other. It is important to know what is happening on local markets. Three points are to be observed: ? what is the demand, ? who are the suppliers and ? what are the prices paid for the various products.

With this knowledge choices can be made about the type of mushrooms to be grown, location, transport to the markets, packaging and presentation of the products. Who are the customers and what are they interested in.

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Middleman or farmer group Choices also have to be made about selling to supermarket(s) through a middleman or jointly through a group of small-scale growers. Most likely the middleman will pay directly whereas most supermarkets have a delay in payment of a few weeks. Marketing plan All these points can be laid down in a marketing plan. The more information is available the better decisions can be made. Calculating the cost price is most vital; when the cost price is higher than the market price it is not beneficial to cultivate these mushrooms. An interesting point in this calculation of the cost price is the cost of labour. It makes a big difference if the small-scale grower can do this activity in his spare time or whether he has to hire labour to do the job for him.

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Further reading The Cultivation of Mushrooms, 1988, edited by van Griensven; English edition: Darlington Mushroom Laboratories Ltd. Price: approximately US$ 25, available at CCO, Horst, the Netherlands All the aspects of Agaricus production around 1987 in The Netherlands are treated extensively. The situation in The Netherlands has changed since then, but the book remains valuable for it’s in depth treatment of all aspects of mushroom growing. The chapters on breeding, spawn production, compost preparation, organisation, and climate control are of interest to Agaricus-growers all over the world. Edible and poisonous mushrooms of the world, 2003, New Zealand Institute for Crop and Food Research, by I. Hall e.a. ISBN 0-478-10835-4 370 pages of general information on mushrooms: which wild mushrooms to pick, how to grow them, poisonous mushrooms of the world, with 250 high quality colour pictures. Mushrooms: cultivation, nutritional value, medicinal effect, and environmental impact, 2004, by S. T. Chang and P.G. Miles. Boca Raton, Fl (etc): CRC Press. US$ 159.95. ISBN 084931043 This book contains the latest cultivation and “techno biological that contribute to the modernization of the mushroom farming. It presents the individual steps of the complex mushroom cultivation process, not only the “how but also the “why” is explored. The Mushroom Cultivator. A practical guide to growing mushrooms at home, 1983, P. Stamets and J.S. Chilton, Agarikon Press, Olympia, Washington. Price: approximately US$ 35. ISBN 0 9610798-0-0 Good descriptions of sterile techniques spawn production, compost preparation, and a key to common contaminants in agar cultures. Specific information on tropical mushrooms is limited, but the book pro-

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vides a good overall view of many aspects of mushroom production, including that of hallucinogenic Psilocybin and Agaricus. Mycelium running: how mushrooms can help save the world, by P.Stamets, Berkeley, CA:Ten Speed 2005. US$ 35 ISBN 1580085792, ISBN9781580085793. A comprehensive guide which capitalises the digestive power of mycelium and unveils new methods for growing mushrooms. Has chapters on nutrition, medicinal properties, log and stump culture and natural culture, using easy to use and low-tech techniques, and much more. In total, 28 species are fully described. Heavily referenced and beautifully illustrated. La culture des champignons, J.M. Olivier e.a, 1991. ISBN 2-200-37242-6 This French pocketbook describes the cultivation of Agaricus bisporus, Pleurotus spp, Lentinula edodes, Lepista nuda, Stropharia rugoso annulata, and discusses truffle cultivation together with host trees. An introduction to the larger fungi of South Central Africa, 1994 by L. Ryvarden, G.D. Piearce and A.J. Masuka. Published by Baobab, Zimbabwe. ISBN 0-908311-52-4 A guide to the most common edible and poisonous mushroom species in Malawi, Zambia and Zimbabwe. 200 pages, coloured pictures. Contains more information than Edible mushrooms of Tanzania. Mushroom Cultivation, Appropriate technology for mushroom growers, third edition, by Peter Oei, Backhuys Publishers, Leiden The Netherlands. Also available from CTA = no. 1146, 40 credit points. ISBN 90-5782-137-0

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Useful addresses ASEMM African Society for Edible and Medicinal Mushrooms E: info@asemm.org Christiaens Group Witveldweg 104-106-108, 5961 ND Horst, The Netherlands T: + 31 77 399 9500, E: hvousten@christiaensmachines.com F: +31773999561, W: www.christiaensgroup.com The Christiaens Group consists of 3 divisions: Construction, Controls and Machines. The Christiaens Group is setting up turnkey projects on Mushroom Cultivation as well as on Waste Management worldwide. Within the Group there is a long experience in the fields of Building Construction, Construction of Machinery and Control Systems. Not only turnkey projects are important but also small-scale projects are given adequate attention. CNC Postbus 13, 6590 AA Gennep, The Netherlands T: + 31 (0) 485 51 6541, F: + 31 (0) 485 51 7823 E: info@cnc.nl, W: www.cnc.nl A large number of the Dutch mushroom growers is associated in the CoÜperatieve Nederlandse Champignonkwekersvereniging U.A. Its cornerstones are the production of full-grown compost and casing soil for the cultivation of mushrooms through CNC Grondstoffen B.V. and the canning of mushrooms through Lutèce B.V. C Point P.O.Box 6035, 5960 AA Horst, The Netherlands T: +31 77 3984555, F: + 31 77 3984160 E: info@cpoint.nl , W: www.cpoint.nl C Point, Training and Consultancy for mushroom growing; trains and advises mushroom growers and their employees in all aspects of mushroom cultivation.

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Gicom b.v. Oostweg 9, 8256 SB Biddinghuizen, The Netherlands T: + 31 (0) 321 332682, F: + 31 (0) 321 332784 E: info@gicom.nl , W: www.gicom.nl Gicom Composting Systems constructs all features/facilities for mushroom cultivation such as compost yards, tunnels and growing houses. All climate control equipment is manufactured, delivered and installed by Gicom Composting Systems too. Apart from GCS manufacturing installations for Waste Treatment, Air Purification and Biological Drying. All machines and process control systems for these installations are manufactured as well. Hoving Holland P.O.Box 9, 9500 AA Stadskanaal,The Netherlands. T: + 31 599 613390, F: +31 599 619510 E: info@hoving-holland.nl , W: www.hoving-holland.nl Hoving Holland is manufacturer of machinery and composting systems for the mushroom industry and exports to many countries. In addition they construct equipment for organic waste disposal. They are among the distinguished leading suppliers of global turnkey projects. ILEIA Centre for Information on Low External Input and Sustainable Agriculture. Promotes exchange of information for small scale farmers in the South through identifying promising technologies. Information about these technologies is exchanged mainly through the LEISA Magazine. All articles accessible on-line. Contact: ILEIA, Zuidsingel 16, 3811 HA Amersfoort, The Netherlands T: +31(0)33-4673870, F: +31(0)33-4632410 E: ileia@ileia.nl, W: www.leisa.info International society for mushroom science ISMS Secretary PO Box 11171, Centurion, Pretoria 0046, South Africa T: +27 12 665 2210; F: +27 12 665 2212 E: secretary@isms.biz, W: www.isms.biz

Useful addresses

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Lenssen Vul- en Sluittechniek b.v. P.O.Box 6848, 5975 ZG Sevenum, The Netherlands T: + 31 77 4672157, F: +31 77 4673775 E: lenssen@lvs-bv.nl, W: www.lvs-bv.nl LVS provides machines and complete production lines in the area of food processing. Used and new machines and complete production lines are utilised for suitable and custom-made solutions. Worldwide assembly, commissioning and service. Highly experienced in mushroom processing. Mushroom Business Reed Business Information bv. P.O. Box 16500, 2500 BM The Hague, The Netherlands T: +31 (0)70 441 5060, F: +31 (0)70 441 5902 www.mushroombusiness.com Mushroom Business is a two-monthly, international trade journal for the worldwide mushroom industry (growers and suppliers). It features articles on growing techniques, markets and marketing, cultivation tips, research, industry news, opinion, and more. The site of Mushroom Business has links to the major suppliers of mushroom equipment, training etc. Mushworld: www.mushworld.com Non-profit organisation devoted to poverty alleviation in the world through mushroom growing, especially in developing countries. Mycelia Veldeken 38, 9850 Nevele, Belgium T: +32 (0) 9 228 7090; F: + 32 (0) 9 228 8928 E: info@mycelia.be , W: www.mycelia.be Mycelia produces mother cultures, mother spawn as well as final spawn in a wide range of edible and medicinal mushrooms. Advises and Training on Spawn production technology are given on demand. Mycelia produces autoclavable and gas permeable Micro sacs速 for fermentation processes as well as sterilized, gas permeable Micro boxes速 for the propagation of plants.

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PUM, Netherlands Senior Experts P.O. Box 93078, 2509 AB The Hague, The Netherlands T: (+31) (0)70 349 05 55, F: (+31) (0)70 349 05 90 E: info@pum.nl, W: www.pum.nl PUM sends senior experts to more than 70 countries in Africa, Asia, the Middle East, Latin America and Central and Eastern Europe. Upon request, PUM’s experts offer their skills and experience to businesses and organisations in places where these are most needed. In the course of their careers, PUM’s advisers have gained extensive experience in nearly every conceivable field. These experts are independent and work on a voluntary basis (they receive no wages). Scelta BV Heymansstraat 35, 5927 NP Venlo, The Netherlands T: +31 77 324 10 20, F: + 31 77 324 1029 E: Sales@sceltamushrooms.com, W: www.sceltamushrooms.com Scelta Mushrooms is responsible for the sales and marketing of (frozen) mushrooms of several partner companies to customers around the globe. Scelta has a production unit for “added-value” mushroom products as breaded mushroom snack or pre-fried mushrooms to be used as a component in ready-made meals. In cooperation with a partner company Scelta produces mushroom flavour products in powder and liquid form to be used by the food industry. Spore Mushroom Products / Stichting ECO Consult Gargouille 1, 4007 RE Tiel, Netherlands T: + 31 (0)6 515 42 882, F: 0344 630 225 W: www.spore.nl Information on special plastic bags for spawn production and on international training activities. E-mail for training courses to info@spore.nl. World Mushroom Society: www.worldmushroomsociety.com The objective of the WSMBMP is to promote knowledge related to mushroom biology and mushroom products. W: www.fungitec.com, Website in English and Spanish Advisory, workshops, short courses and mushroom projects.

Useful addresses

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Appendix 1: Formulas Formulas for media PDA: Potato Dextrose Agar extract medium 200 g diced potato, 20 g agar powder, 20 g dextrose or ordinary white cane sugar, 1 litre water. Compost medium 300 g dried compost (pasteurised) in 4 litres of boiling water. After 15 minutes filter the water and add water until you have 4 litres again. Then, add 10 gram of agar per litre of water Malt Agar 0, 4 litres brewery malt solution. 0, 8 litres water 15 grams agar. Formulas for spawn substrate Grain spawn substrate Grain in small containers can be moistened to a higher degree than grain in 15 litre bags.

For 2 litre containers, use the following recipe: 400 g rye, sorghum or wheat, 400 ml water, 2 g gypsum (45% moisture).

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Appendix 2: Air quality test Choose a horizontal surface, centrally located in the room where you wish to test the air quality. Open a Petri dish with test medium, i.e. agar with nitrogen- and carbonsource, and put the lid upside down next to the Petri dish, making sure not to touch the agar surface. Sampling period: clean room area: 1 hour workshop area: 10 minutes Close the Petri dish with adhesive tape and place it in a warm room (20 à 25 °C) for incubation. After 3 to 4 days you can analyse the results.

Courtesy of Mycelia

Appendix 2: Air quality test

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Appendix 3: Different origins of contamination Quality control Quality control in spawn manufacturing includes: ? constant inspection of the inoculated containers and ? maintaining a strict hygienic regime. Unhygienic conditions Unhygienic conditions during inoculation may give rise to a variety of different fungal contaminants. Remove and pasteurise/sterilise the contaminated containers and open and clean them only after pasteurisation/sterilisation.

Insufficient sterilisation Insufficient sterilisation often leads to outbreaks of bacteria and/or unwanted fungi ? greasy appearance on grain spawn Improper storage Improper storage refers to spawn that has not been stored properly (i.e. too warm or too cold), or when substrate in the containers has dried out Storage and purity Good spawn shows vigorous growth and contains no other organisms. If the storage period has been too long, its vigour will be diminished. Opened containers with spawn Opened containers with spawn should be removed immediately from the growing site after usage and should under no circumstances be reused. Do not use half a bottle because contaminants will spoil the rest of the spawn.

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Infestation Infestation can occur without visible signs (of contamination) at the beginning of the infestation. Refrigerated spawn Refrigerated spawn can be kept for up to six months after complete colonisation of the substrate.

Courtesy of Mycelia

Appendix 3: Different origins of contamination

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Appendix 4: Culture transfer in detail

1 Sterilise the scalpel in the flame until red-hot. 2 Take the cotton plugs out of the test tubes and keep them in hand (meanwhile the scalpel has the time to cool down). 3 Keep the mouth of both test tubes above the flame. 4 Cut a small square (5 x 5 mm) from the ÂŤ mother Âť test tube culture.

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5 6 7 8

Put the square in the middle of the agar surface of the new test tube. Reheat the mouth of both test tubes in the flame for 3 seconds. Replace the cotton plugs. Sterilise the scalpel in the flame once more and repeat the procedure for the next transfer.

Appendix 4: Culture transfer in detail

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Appendix 5: Formulas for compost Compost formulas for Button Mushrooms (Agaricus spp) Formula 1 1000 kg straw rich stable manure or straw mixed with chicken manure thoroughly mixed with 10 kg of chalk. Water is added until it leaks out the pile. Formula 2 (to be used if no manure is available) Straw 1000 kg Urea 10 kg Ammonium sulphate 20 kg Potassium sulphate 8 kg Calcium carbonate 25 kg Compost recipe bagasse (weight percentages) Rice straw Sugar cane bagasse Chicken manure Gypsum Soybean meal Urea

35% 33% 25% 5% 2% 1%

Compost formulas for Rice Straw Mushrooms (Volvariella spp) in weight percentages Formula 1 Paddy straw Cotton waste Sugar cane waste Cotton waste/paddy straw mixture

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14-28% 25-45% 12% 22%

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Formula 2 Rice straw Cotton waste Rice bran Lime

45% 40% 10% 5%

Formula 3 Dry cotton waste Rice bran (supplement) Limestone (pH regulator)

90-92% 4% 4-6%

Formula 4 Cotton waste Rice straw Limestone

50-75% 25-50% 3-4%

Formula 5 Spent substrate from Agaricus cultivation Cotton waste

50% 50%

Formula 6 Chopped water hyacinth Rice straw

50% 50%

Formula 7 Rice straw Sugar cane waste (bagasse) Chicken manure Gypsum Dash of urea

40% 29% 29% 2% about 0.1%

Appendix 5: Formulas for compost

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Appendix 6: Simple steaming systems

Figure 29: Oil drum steaming system and cross section

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Figure 30: Mobile steaming system and cross section

Appendix 6: Simple steaming systems

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Glossary Actinomycetes:

White filamentous organisms (sometimes similar to fungal hyphae), which occur in well-fermented compost, indicating that the compost is suitable for cultivation of Agaricus spp. Air lock: Enclosed section with gates at each end in order to prevent outside air entering directly the growing room. Agar: An extract from a seaweed used to solidify media: alternatively, (cheaper) gelatine may be used. Agar is available in bar or powder form. Anaerobic: Without oxygen (O2). Aseptic: Sterile condition: no unwanted organisms present. Autoclave: A container or any form of pressure cooker in any dimension (small or big) the contents of which can be heated up to 121 째C. It must be able to withstand an overpressure of 1 bar; otherwise the temperature cannot rise sufficiently. Bacteria: Microorganisms that may cause contamination in culture work. Grain spawn is very easily contaminated with bacteria. Break: See flush Button stage: The young mushrooms are still fully closed. Cellulose: An organic compound in wood, straw, etc. It is easier to degrade than lignin. Cellulose is probably best known as raw material to make paper. Cotton waste contains high amounts of cellulose; sawdust contains cellulose, hemi-cellulose and lignin. Conditioning Gradual lowering of the temperature within one or two days in order to get rid of the free ammonia in the compost. Culture: See mother culture. Culture medium: Microorganisms differ in their nutritional needs. A large number of different media have been devel-

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oped; PDA-agar and Malt-agar can be used for most cultivated mushrooms. Fermentation: The process of composting. Easily accessible nutrients will be degraded by microorganisms that make the substrate more selective. Unwanted fermentation may occur if the compost is still very ‘active’ or if thick layers or large bags are used. In that case the temperature rise inside the substrate will become too high for the desired mycelium. Flush: The sudden development of many fruiting bodies at the same time. Usually there is a resting period between flushes or breaks. Formol: A 30% solution of formaldehyde used to sterilise areas. The gasses kill living microorganisms and spores. Free water: The actual water available to the microorganisms in the substrate. Water content is the absolute measure. Free water is related to the water film around each particle in the substrate and the concentration of salts in the water. Fruiting: The mycelium will form mushrooms in its reproductive stage. This is called fruiting as the mushrooms are actually the fruiting bodies of the mycelium. Germination: The spreading of hyphae from spores. Gills: the radially arranged, vertical plates below the cap of a mushroom on which spores are formed. Hyphae, hyphae: Individual cells of mycelium. Incubation: The period after inoculation (preferably at an optimum mycelial growth temperature) during which the mycelium slowly grows through the substrate Inoculation: Transferring an organism into a specific substrate. Lamellae: See gills Lignin: An organic substance that is difficult to degrade, which, together with cellulose, forms the basis of wood, straw, etc.

Glossary

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Microorganisms: Microscopic organisms which are abundantly present in the air and stick to every surface. (Mother) culture: A pure strain of an edible fungus growing on a medium. Mother spawn: Spawn that is not used for inoculating substrate, but for inoculating another batch of spawn. Mycelium: The network of hyphae that form the vegetative body of the fungus. Mushrooms are the fruiting bodies of the mycelium. Mycorrhiza: A symbiotic relationship between fungi and plant roots. Parasite: Organism that lives at the expense of others, usually causing diseases in its hosts. Ultimately it may cause the death of its host. Pasteurisation: Heat treatment applied to a substrate to destroy unwanted organisms but keeping favourable ones alive. The temperature range is 60-80째c. The treatment is very different from sterilisation, which aims at destroying all organisms in the substrate. Petri dish: A round glass or plastic dish, with a cover, used for observing the growth of microscopic organisms. The dishes are partly filled with sterile growth medium (or sterilised after they have been filled). Petri dishes are commonly used to grow mycelium that will inoculate the mother spawn. Peak Heating: Pasteurisation of the compost in the growing rooms Pinhead: A term to describe a very young mushroom, when the cap is pin-sized. Primordium: The initial fruiting body. Pure culture: An isolated culture of a microorganism without any other microorganisms. Pure cultures are essential to the spawn production process. Relative humidity: The percentage of moisture in the air compared to the maximum amount of moisture that the air can contain at a given temperature and pressure.

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Saprophytes:

fungi that break down complex organic structures of plants and animals in order to feed on them Saprophytic mushrooms: e.g. Agaricus spp and Volvariella spp. Stem: stalk of a mushroom Slant: A test tube with growth medium, which has been sterilised and slanted in order to increase the surface area. Spawn: Mycelium growing on a substrate used as planting material in mushroom cultivation. Spawn run: The period of vegetative growth of the mycelium throughout the substrate after spawning. Species: Fundamental unit of biological taxonomy. Generally speaking, two individuals belong to the same species if they can produce fertile offspring. SMS: Spent Mushroom substrate, the substrate remaining after the mushrooms have been harvested. Spores: The means of reproduction in fungi. In cultivated mushrooms they are formed on the gills and dispersed in the air. One mushroom can produce millions of spores. Sterile: Conditions: see aseptic. Sterilisation: Destroying (completely) all microorganisms present, by heat. Spawn substrate always has to be sterilised prior to inoculation. Stipe: Stalk of a mushroom. Strain: A group of individuals within a species. Equivalent to “race” or “variety” in plants. Subculture: A culture derived from another culture. Substrate: the material in which the mycelium grows. Taxonomy: Science of classification of living things Test tube: A tube of thin, transparent glass closed at one end used in chemical and biological experiments. Tissue culture: A culture made from the tissue of a young and healthy mushroom. Veil: Layer of tissue that completely surrounds the baby mushroom.

Glossary

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Small-scale mushroom cultivation  

Agrodok 40 Peter Oei with contributions by Bram van Nieuwenhuijzen oyster, shiitake and wood ear mushrooms ISBN Agromisa: 90-8573-038-4 ISBN...

Small-scale mushroom cultivation  

Agrodok 40 Peter Oei with contributions by Bram van Nieuwenhuijzen oyster, shiitake and wood ear mushrooms ISBN Agromisa: 90-8573-038-4 ISBN...

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