mushroom production

Basic Requirement:

Substrate

Substrate is any material used to support growth of crops instead of soil.  Mushroom can be classified as:

-          Primary decomposers of organic matter (like wood, leaves and straw in nature) e.g. shitake and oyster mushroom,

-          Secondary decomposers-matter degraded by bacteria or other fungi e.g. button mushroom

Examples of Agricultural waste substrate materials include:

Wheat straw, banana leaves, banana pseudo stems, barley straw, bean pods/straw, coconut fibre,coffee parchment, coffee pulp, coffee sawdust, corn fibre, corn cobs, corn stovers, cotton straw, cotton husks, grass, groundnuts shells, legume straws, paper pulp, potato foliage, rice straw, saw dust, sorghum stover, sugarcane bagasse, sunflower stypes, tea leaves, water hyacinth, wood shavings.

Factors to consider in substrate selection

• High yielding substrate
• Ease of use
• Cost of substrate
• Availability
• Storage
• Cost of transport
• Clean (without moulds/coloration)
• If possible from the previous harvest

Mushroom Housing

Materials used include: -

• Steel structure tubing covered with tarpaulin
• Bamboo woven matting insulated inside with polythene sheets.
• Grass thatched houses or with shade cloth thatching
• Green houses clad with insulation (glass wool) and roof vents
• Mud walled house

Housing conditions: -

i) Temperature

• Incubation 20 -27^o C
• Fruiting/pin formation 10-18^o C

ii) Humidity

• Substrate moisture - 60-70%
• Fruiting body 80-95% humidity

iii) Light- Mycelia growth (Incubation) can take place without light

- Fruiting body (mushroom growth process) requires light

iv) Ventilation -Fungi are aerobic therefore need fresh air especially during the reproduction stage.

The Process of Mushroom Growing:

Substrate preparation

• Sterilization/pasteurization (decontamination) of substrate
• Inoculation (spawning)-This is introduction of seeds to substrate
• Fruiting (growth processes of mushroom)
• Harvesting, post-harvest handling
• Marketing

Substrate preparation for oyster mushroom:

The best substrates for oyster mushrooms include wheat straw, banana leaves, cotton seeds hull, rice straw. Unlike others, Banana leaves and cotton seed hulls may not require supplementations.

The main supplements used are wheat bran and rice bran.

Good substrate should have a C: N ratio of 2:5

Steps:

i) Substrate mixing ratio:

To make 10kg of substrate: use bulk substrate (wheat straw) 80% = 8kg, supplement (wheat bran) 20% = 2kg and buffer lime 1% of 10kg) =100grams

Note: Buffer is used to maintain pH at 6.5-7.0

Lime (Ca (OH)_2, Chalk (CaCo₃) or  Gypsum (CaSo₄) can be used

ii) Shredding - cut bulk substrate into 2-3cm (one inch)

Soaking - put cut material in gunny bag and soak it in water for 2 hours to attain 70% moisture content.

Remove it from gunny bag, spread it on a clean polythene sheet and use Squeeze/fist method to verify 70% moisture content. Pick a handful, when squeezed it gives 2-3 drops of water.

Then sprinkle wheat bran, lime, and mixed thoroughly.

Bagging - Put mixture in polythene bags - 9×15 inches neck with a ³/₄ inch piece of PVC pipe,  plug with the mouth with  a piece of cotton wool, tie, and covered with 10 x15 inch polythene bags.

Decontamination of Substrate

Sterilization- Put bags in an autoclave and heat to 121^oC for 60-90 minutes to kill all micro-organisms, leaving a biological vacuum

Pasteurization- uses low heat

Pasteurization methods:

-          Immersion in hot water; Put substrate in gunny bag and immerse it in hot water at 60C^o for 30 minutes to kill competitors while leaving friendly micro-organisms like thermophiles.

-          Oil drum steaming; place the two kg substrate - filled bags- on the rack inside the oil drum, already containing 40 litres of clean water then seal then steam the content for 3-4 hours

Bulk steaming

Cooling- Cool substrate to 25^o C

Spawning (Inoculation)

Inoculate 30-50 (2 kg) bags with1 litre of spawn

a) Conditions for spawning;

i) Provide sterile conditions for spawning as shown below

Size: - 90cmX60cmX45cm (one plywood is used)

Open the spawning box, thoroughly disinfect the inside using 70% alcohol or propane, then put substrate bags and spawn them.Put spawns in the bag and then close the bag ready for incubation

b). Incubation

Put the bags under room temperature (25^oC ) for28-30 days until white mass (mycelia) until substrate is fully covered.  Remove and discard contaminated bags.

Do the incubation in the growing house/room with no mushroom growing

Fruiting

Maintain the following Conditions:

Light: one should be able to read a newspaper in the growing room

Temperature: 8-20 ^o C.

Relative humidity: 85-95%

Aeration: keep CO₂ at 0.1%d or 1000ppm by partially opening the windows.

During fruiting remove the cotton wool, rubber band and plastic neck to allow mushroom to grow from the top.

Note: from inoculation to first harvest mushroom takes 2 months

Harvesting

Harvest mushroom by twisting the stem (stype) and uprooting and sell them while still fresh as they are perishable.

Preservation

Oyster mushroom can be preserved for several days.

Short term storage- refrigeration at 1- 4⁰ C keeps them good for 6 days

Long term storage:

1) Dry at10% moisture content.

a) Sun drying

b) Thermal drying

2) Canning

3) Pickling - storing in brine (21% salt)

iv)  Blanching- shortly cooked and the transferred to salty water.

Mushroom Monitoring and Evaluation:

Monitor for:

• Rodents and pathogens like fungi, bacteria, virus and ants

Temperature-uniform/constant temperature

• Humidity- Maintain at 85-95% or even 100% by avoiding opening of the windows wide open.
• Light- enough to enable reading a newspaper for fruiting to occur.
• Aeration-by ventilation as they are sensitive to CO₂.

Button Mushroom Production;

Fruiting body has the shape of a button.  Button mushroom is also called white buttom mushroom or champignon.Button mushroom is a secondary decomposer i.e. it cannot feed on fresh substrate but instead the substrate must be decomposed first.

Process of Growing Button Mushroom

This involves:

a. Composting substrate; Phase one,  Phase two, Pasteurization,Final conditioning

b. Spawning

c).  Incubation

d). Casing

e). Fruiting.

Composting

Substrate formulationButton mushroom is coprophagous (grows on manure).  Traditionally it was grown on horse manure, which is scarce hence the need for another substrate.

Preparation of artificial compost;

• Wheat straw - 40Kg Ammonium sulphate1.2kg Manure 6.8kg Urea 0.7 kg Super phosphate 1.2kg Calcium carbonate (chalk) 1.2kgProcess of composting:The purpose of composting is to make the substrate selective to Agaricus bispora and non-selective to other fungi.

i) Phase 1 of composting: Wet the rice straw thoroughly - spray water to the straw till water starts running. Blending - mix the ingredients thoroughly; Make a narrow heap or stack of 1.5m X 1.5m height and convenient length.  This will ensure adequate aeration. Too large heaps will lead to anaerobic conditions at the center of the heap.Turning of the heap every other day to ensure uniform decomposition.

Attributes of ready substrate: -

a. Substrate becomes pliable - bends very easily

b. Substrate absorbs water - improved water holding capacity

c. Substrate turns to dark brown

d. Very strong smell of ammonia

ii) Phase II of composition-

-Done in the mushroom growing house. The mushroom house has beds to contain the substrate.

Pasteurization

Transfer substrate from outside onto beds in the mushroom house and be fast enough to avoid cooling of the substrate. The temperature of the substrate should remain at 55oC during the transfer. There should be no mushroom growing in the house at the moment. Fill the whole house with substrate.Close the windows and let the substrate heat itself up to 60oC.  Easily accessible sugars and nitrogen in the form of ammonia will be used up.  This will be incorporated into microbial tissue when they die.
Maintain temperatures at 60oC for 6 hours by controlling ventilation.A small mushroom house may not generate 60oC so steam source may be done.

Conditioning:

Lower temperature from 60-50oC (by ventilation) should be used for a period of 12 hours.  During conditioning, ensure aeration to avoid anaerobic conditions.  Aeration should ensure that there is 1.5-2.5% carbon dioxide tested by lighting a match stick, if it goes off immediately, carbon dioxide is too high.
Nitrogen in the form of ammonia and any simple carbohydrates can be depleted from the substrate at 50oC for 5-7 days. This will ensure that ammonium ions are below 10-ppm. Easily tested by smelling the substrate for ammonia gas.Then cool the substrate suddenly to 25oC for spawning.

Spawning

Make a hole, using a finger on the bed 2″ deep and plant spawn at a spacing of 9-12″.  Spawning rate is 7kg of spawn per tone of wet substrate.After planting the spawn, sprinkle some spawn on the surface of the substrate to accelerate colonization and prevent contaminations.

Incubation

Best temperature of growth of button mushroom mycelia is 25oC of the substrate.  Occasionally, spray some water on the surface of the substrate.  Take 2 weeks to start fruiting.

Casing

After substrate is fully colonized (fully white), add casing soil - Button mushroom mycelia will not form primordial unless there is casing soil.  Casing will trigger fruiting.Casing material preparation is done outside the mushroom house.The materials include real/garden soil with enough humus.Sieve it to remove the stones, spray formalin (to disinfect the soil) into the soil.  Cover with polythene sheets and let it remain covered for 2 days to kill any soil fungi, nematodes and tiny insects.Apply a layer 2″ deep of casing soil on top of the mycelia.  When mycelium appears on the surface you the will trigger fruiting.

Fruiting

Environmental conditions necessary for button Mushroom fruiting

Temperature Agaricus bisporus 12-1o8 C

Agaricus bitorquis 21-25o C

Relative humidity 85-95o C

Aeration - Bring down carbon dioxide to below 600ppm or 0.06% CO2

After 7 days, pin heading (germination) and fruiting (growth) will start.

Harvesting/Yields

Picking is done with a second flush after one week.  There can be upto  6 flushes.Average yield is 33kg of fresh mushroom per square meter of compost.
NOTE: The main substrates for button mushroom production are rice straw, wheat straw and sugarcane bagasse.  Other types of substrates cannot be standardized for use.

Shiitake Mushroom Production;

It is also called black forest mushroom or log mushroom (Lentinula edodes).

Traditional method of growing shiitake in Japan is growing it on wood logs but in USA and China they found it easy to grow it on synthetic logs due to environmental conservation.

Synthetic Log Method:

Synthetic bag can be made using substrate placed into plastic bags.  Substrate + supplements + buffers

a) Substrate formulations

i) Substrates-Sawdust (cured if not from broad leafed tree varieties), cottonseed hulls, coffee hulls, corn cobs, sunflower seed hulls

ii) PH buffer use calcium carbonate or calcium hydroxide.

iii) Supplement with brown sugar

N.B. Keep bags on cemented floor for better results

Substrate preparation is done same way as oyster.

Incubation stages

1. Spawn run or mycelia growth stage- stage during which digestion of food takes place

2. Mycelial coat formation - mycelia will thicken and become dense forming a coat on the outer side of the sawdust or substrate

Environmental factors triggering coat formation are:

Carbon dioxide: - the higher the CO₂, the more the coating and the better the crop.

3. Bump formation on the substrate coat:  This stage can be called the blister stage, popcorn stage.  Too many bumps will increase chances of contamination so reduce the number of bumps by lowering CO₂ levels on bags by cutting slits on the polythene bags.

4. Browning\pigmentation\coat hardening

Oxygen stage and Diffused light-.  In the presence of oxygen and light, oxidation occurs and the white Mycelia turn reddish brown on the surface of the mycelia while middle of the bag remains white.  When one third of bag turns brown, they are ready for fruiting.

Fruiting

Is triggered by changing the environment:

Light

Humidity

Temperature

Aeration

Ways of triggering fruiting

Spraying cold water

Physical shaking

Soaking in cold water

Electrical stimulation

Harvesting

Shiitake mushroom will be ready for picking after 8 days.  After 14 days you can get another flush.  First flush of shiitake mushroom comes 3-4 months of incubation.  There can be a total of 4 flushes.

After harvesting separate harvested bags from the rest to reverse the environment as it was in beginning

GANODERMA SPP

Most common species;

Ganoderma luciderm.

Other species are

Ganoderma applanatum

Ganoderma oregonense

It is not an edible mushroom but most important medicinal mushroom.  It has been documented in material medical and classified as a superior herb 2000 years ago.

As a medicinal mushroom, it is used in small\low doses and costs US$500/kg

Has similar production process as oyster mushroom but incubation takes place at 85% RH.  It forms a wide primordial (pin heading) margin which disappears when the mushroom is ready for picking.

Primordial formation to picking takes 3- 4 weeks.

Utilization of Ganoderma:

Dry the ganoderma mushroom (this will keep for long), grind.  Boil powder in water.  Let it simmer for 30-60 minutes. It is used in manufacturing of mushroom tea/ coffee

Pests,Diseases and their Control:

(i)    Sanitation and hygiene;

- Clean and disinfect mushroom houses thoroughly before cultivation.

- Remove any waste, weed, mushroom debris and water containers inside and outside the mushroom houses that attract flies or on which flies can live.

- Exclude flies by use of mesh apertures not greater than 0.5-0.6mm on all inlets.  Keep doors closed, particularly during spawning and mycelium growth phase.

- Maintain insect free environment by burning mosquito coils

(ii)  Chemical control- use of chemicals is rare;

(iii)  Abnormalities in Fruiting Body;

Maintain required environmental conditions e.g. temperature, relative humidity, Co₂ concentration and moisture content in the mushroom substrate.

Effects of high temperature and humidity;

Cap: stype ratio is small than normal

Cap Colour becomes lighter (grayish brownish) and depression in the center.

Importance of Mushroom Cultivation:

The Importance of Mushroom Cultivation

• Nutritional value
• Protein content, 3-7% when fresh and 25- 40% when dry. Contain all essential amino acids, amides and lysine.
• Medicinal value
• Consumption of mushrooms slows down the spread and effect of cancer, heart disease, HIV/AIDS (by boosting immune system).
• Income generation and
• Employment creation.

Advantages of Mushroom Growing

• Use of idle structures,
• Involvement of small initial capital,
• Possible production all the year round
• Use of Agricultural waste as substrate- mostly waste materials from farms, plantations or factories.
• Is a Biodegrader hence environmental con-server.

Consumption benefits of mushrooms.

• Contain all essential amino acids
• Has Vit.C, cynocobalimin (Vit,B12) content found only in animal products
• Low in sodium ideal for people with heart and kidney ointments.
• Have iron, calcium, potassium, phosphorus and folic acid.

Challenges in Mushroom Growing

• Lack of skills on mushroom production
• Spawn is expensive and quality not guaranteed
• Lack of awareness of  benefits of mushroom
• Traditional beliefs of some communities