🍄Mushroom Cultivation -- From Solan to Your Plate (Button, Oyster, Paddy Straw & Exam Facts)

From Forest Floor to Farm Income

In the cool hills of Solan, Himachal Pradesh — rightly called the Mushroom City of India — rows of climate-controlled growing rooms produce tonnes of white button mushrooms every winter. A farmer fills trays with composted wheat straw, mixes in grain-based spawn, covers the surface with a thin casing layer, and within three weeks the first flush of mushrooms pushes through. Mushroom cultivation is unique in agriculture: there is no soil, no sunlight, and no photosynthesis — instead, the crop feeds on decomposing organic matter in the dark.

This lesson covers:

1. What mushrooms are — classification and edible types
2. Button mushroom cultivation — the six-step technology (spawn to fruiting)
3. Other commercial types — oyster and paddy straw mushrooms
4. Pests, diseases, and poisoning — exam-critical identification facts

All sections are high-yield for IBPS AFO, NABARD, and ICAR exams.

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What Is a Mushroom?

A mushroom is a fleshy fruiting body of certain fungi, arising from a network of mycelium (thread-like fungal cells) buried in the growing substrate. Mushrooms are not plants — they lack chlorophyll and cannot photosynthesise. Instead, they obtain nutrition by decomposing organic matter.

• Most edible mushrooms belong to the Sub-Division Basidiomycotina
• A few belong to Ascomycotina of Kingdom Fungi
• Mushroom City of India: Solan (Himachal Pradesh)

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Classification of Edible Mushrooms

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Button Mushroom (Agaricus bisporus) — The Dominant Species

Key Facts

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Nutritional Value

Button mushrooms are a low-calorie, high-protein food source with negligible fat:

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Growing Conditions — Vegetative vs Reproductive

The growing conditions for the two stages are opposite in temperature and CO2 requirements — a frequently tested distinction:

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Six-Step Cultivation Technology

Button mushroom cultivation follows a precise sequence — each step creates the conditions needed for the next. Deviations in temperature, humidity, or CO2 at any stage can ruin the entire crop. Understanding this sequence is essential for both practical cultivation and exams.

The cultivation of button mushroom involves 6 sequential steps. Understanding this sequence is essential for exams:

Spawn Production —> Compost Preparation —> Spawning —> Spawn Running —> Casing —> Fruiting

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Step 1: Spawn Production

• Spawn = the vegetative mycelial network of a mushroom developed after germination of fungal spores, grown on a convenient medium
• It comprises mycelium along with a supporting medium providing nutrition
• Master culture and spawn are produced on wheat or rye grains buffered with Calcium carbonate (CaCO3) and Calcium sulphate (CaSO4)

Think of spawn as the “seed” of mushroom cultivation. Just as a farmer needs quality seed for a good crop, quality spawn determines the success of mushroom production.

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Step 2: Compost Preparation

The substrate for button mushroom is prepared from:

• Plant wastes: cereal straw, sugarcane bagasse, etc.
• Salts: urea, superphosphate, gypsum
• Supplements: rice bran, wheat bran
• Water

Key ratios and requirements:

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Step 3: Spawning

• The process of mixing spawn with compost is called spawning
• Spawn is thoroughly mixed into or layered onto the compost in growing trays or beds
• Uniform distribution of spawn ensures even colonisation of the compost

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Step 4: Spawn Running

• Fungal mycelium grows out from spawn grains and colonises the compost in about 12-14 days (2 weeks)
• Temperature maintained at 23 +/- 2°C
• Relative humidity: ~90%
• Higher CO2 concentration (5,000-10,000 ppm) is beneficial at this stage
• Higher temperature is detrimental; lower temperature causes slower spawn run

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Step 5: Casing

After complete spawn run, compost beds are covered with a layer of soil (casing) about 3-4 cm thick to induce fruiting.

Alternatives used in India:

Casing soil must be sterilised before application:

• Pasteurised at 66-70°C for 7-8 hours
• OR treated with Formaldehyde (2%) + Bavistin (75 ppm)
• OR steam sterilised
• Treatment must be done at least 15 days before use

After casing: temperature maintained at 23-28°C, RH 85-90% for 8-10 days. Low CO2 is favourable for the transition to reproductive growth.

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Step 6: Fruiting

• Induced by lowering temperature to 17 +/- 1°C
• Humidity: 85-90%
• CO2 concentration: 0.08-0.15%
• Proper ventilation is required to maintain low CO2 levels

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Harvesting and Yield

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Other Important Mushroom Types

While button mushroom dominates Indian production, two other species are commercially important and frequently tested in exams. They differ from button mushroom in climate requirements, substrate, and ease of cultivation.

Oyster Mushroom (Pleurotus spp.)

Oyster mushroom is recommended for beginners because it tolerates a wider range of growing conditions and substrates compared to button mushroom.

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Paddy Straw Mushroom (Volvariella spp.)

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Button vs Oyster vs Paddy Straw — Comparison

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Pests and Diseases of Mushrooms

Mushroom growing rooms provide ideal conditions for pests and pathogens — warm, humid, and rich in organic matter. Maintaining hygiene at every step (from compost preparation to harvesting) is the primary defence. The following pests and diseases are frequently tested in exams.

Insect Pests

Common pests include: Nematodes, Sciarids (fungus gnats), Phorids (scuttle flies), Mites, and Springtails

Diseases

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Mushroom Poisoning

Poisonous mushrooms can cause four types of disorders:

1. Gastric disorder
2. Nervous disorder
3. Muscular disorder
4. Haemolytic disorder

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Summary Table — Mushroom Cultivation Key Exam Facts

Summary Cheat Sheet