Oyster mushrooms

Inspect straw or other approved substrate before using it. Record where it came from and whether storage has allowed rain, visible mould, soil or chemical contamination. A low purchase price is not a saving if preparation losses or crop failures increase. Use a crop-specific treatment method taught by a competent institution; treatment time and temperature belong to the method and load, not to a generic internet recipe.

The treated material must cool under protected conditions before spawn is added. Mixing hot material with spawn, draining on a dirty floor or handling treated and untreated straw with the same equipment creates different failure routes. Identify the transition from raw to treated material physically. Label each treatment load so that later contamination can be traced to preparation, spawn or handling rather than blamed on the whole room.

During colonisation, compare bags from the same batch at the same age. Note the progress of mycelium, stalled areas, damage to packaging and abnormal colour. Keep questionable bags out of routine opening or handling; follow your containment procedure and obtain advice. Opening a suspect bag to smell it spreads material and exposes the operator without reliably identifying the cause.

When the bag is ready, follow the opening and fruiting method for that species. Light, air exchange and moisture management must work together. Long stems or small caps are reasons to inspect crop identity, light and air distribution, not proof of a single cause. Dry margins near a fan and persistently wet clusters elsewhere can coexist in one room; raising the room's humidity setting alone may not solve that distribution problem.

If affected bags from several preparation dates cluster beside one inlet, investigate that location. If one preparation batch performs poorly across several shelves while neighbouring batches grow normally, investigate its materials and treatment record. Both patterns can overlap; map them before changing the whole room.

These are source-specific examples, not a universal relationship between stages. Match the supplier's strain protocol to the measured room conditions. Active substrate can differ from room air; measure both instead of assuming a fixed temperature offset.

The DMR seasonal folder gives a calendar. On the north Indian plains dhingri grows from September to May. In the mid-hills it grows all year. In the high hills it grows from May to August. Coastal states can grow oyster, paddy straw and milky mushroom in the natural climate all year; central and western India can grow dhingri in every season except summer.

Within that calendar, switch species. The oyster folder says: in summer grow P. sajor-caju, P. flabellatus, P. sapidus, P. djamor or P. citrinopileatus; in winter, when air falls below 20 C, choose P. florida or P. cornucopiae.

Temperature also sets colour. DMR reports P. florida caps light brown at 10-15 C but white to pale yellowish at 20-25 C; P. sajor-caju at 15-19 C is white with high dry matter, at 25-30 C brown with less. Below 100 lux of light caps go pale yellow; in bright light dark brown. Buyer preferences vary with market and product. Agree colour, cluster size and maturity with the intended buyer instead of assuming all buyers want white mushrooms.

Then settle the unit. A seasonal room follows the weather and changes species by season. A controlled room holds one band all year at much higher cost. The folder says an 18 x 15 x 10 foot room holds about 300 bags; start with one room and one species.

The substrate is the material the mycelium eats. For oyster in India it is usually wheat or paddy straw; DMR notes most such substrates hold 0.5-0.8 per cent nitrogen, enough without additives. Use fresh, dry straw from the current season, stored under cover; old or rain-wet straw brings ink caps and moulds.

Chop so it packs evenly. The DMR folder machine-cuts hard residues to about 2-3 cm; the 2011 manual chops 5-10 cm for hot water; TNAU uses 5 cm. DMR allows wheat or rice bran as a supplement but warns it raises bag temperature by 2-3 C or more, so not in summer.

Drain until the straw holds about 65-70 per cent moisture, a figure DMR gives in its milky folder for the same treatment. Squeeze test: no drip, palm just damp.

Larger units use steam. The manual packs pre-wetted straw in trays and holds a pasteurisation room at 58-62 C for four hours; the whole cycle takes 3-5 days. The folder's tunnel holds 60-65 C for about four hours.

DMR also describes chemical steeping: straw soaked 12-18 hours in water with a fungicide and formalin, which suppresses competitor moulds for 25-40 days after spawning. This lesson gives no doses; both chemicals carry regulatory and residue conditions, so check current label approval and prefer hot water if unsure.

The sterile method autoclaves soaked straw in polypropylene bags at 20 psi for 1-2 hours. It suits laboratories, not a first farm.

Competitor moulds can cut oyster yield by up to 70 per cent, so prevention beats any cure. DMR asks for the spawning room to be disinfected two days before spawning and kept closed. Wash the draining floor; keep hands, buckets and knives clean.

The opening and drainage pattern belongs to the chosen bag method. It does not by itself guarantee substrate temperature; inspect drainage and measure conditions. Use the supplied product's batch-specific storage and use-by instructions; age alone does not establish quality. Keep flies out with fine net on doors and windows. Keep suspect bags closed and limit movement. Follow a competent containment and locally appropriate disposal procedure rather than dumping material in an outdoor pit.

Spawn is the seed material: grain fully covered in mycelium. Use it fresh. Historical publications give age examples, but product, strain, carrier and storage conditions differ. Use traceable supplier guidance and receiving checks; these examples are not a universal expiry rule.

The manual mixes spawn at 2-3 per cent of wet substrate weight; one 300 g bottle serves 10-12 kg of wet straw. The folder says about 100 g per 4 kg wet straw.

Bag sizes differ by institute: the folder uses 40-45 by 30-35 cm polythene; the manual 60 x 45 cm of 125-150 gauge; TNAU 60 x 30 cm of 80 gauge. Follow the chosen bag system's opening and drainage method. Holes do not guarantee a safe substrate temperature; check conditions with suitable measurements.

Mycelium grows between 10 and 30 C, best at 22-26 C. Above 30 C in the room it stops and dies, and the bag runs 2-4 C warmer than the room. If the bag climbs past 30 C, the folder says to splash water on walls and roof two or three times a day or run an air cooler.

The folder is blunt: during the run the bags need no water, no air and no light. The manual agrees: bags stay closed, no ventilation, no spraying. The mycelium tolerates carbon dioxide up to about 2 per cent, so a closed dark room is fine. TNAU instead asks for 22-25 C with 85-90 per cent humidity in a dark shed.

Days 1-5: white threads spread from each grain. Days 5-12: threads meet and the straw colour fades. The folder expects the whole bag white in 15-25 days. The manual sets a hard rule: never open before 16-18 days, except P. membranaceus and P. djamor var. roseus, which fruit through the holes within 10 days.

Trouble signs: green patches (Trichoderma), black spots, a sour smell, or a wet grey mass at the bottom from excess water. Slow, thin growth points to cold or old spawn. A bag hot to the palm is packed too tight or the room is too warm. Remove a contaminated bag at once and bury it in a deep pit away from the room.

Stack loosely. The manual sets 15-20 cm between bags so heat escapes; tight stacks push centre bags over 30 C. Racks with a gap under each bag drain better than a floor pile.

NHB repeats the ICAR advice to screen doors and ventilators with nylon net of 35 mesh or finer so flies cannot lay eggs in the bags. Keep the room closed; the manual wants it pre-fumigated before spawning and a closed room stays that way.

Work from clean to dirty: good bags first, suspect bags last, wash hands between. The diary tells you next batch whether the straw, the spawn or the room was at fault.

Everything the bag did not need during the run, it needs now: water in the air, fresh air and light.

Fruit at the band for your species: 18-22 C for P. florida, 22-26 C for P. sajor-caju and P. flabellatus, 14-18 C for P. eryngii. Warmer than its band, sajor-caju turns brown and thin.

Relative humidity, RH, is the water in the air as a share of the most it could hold. The manual says all Pleurotus need 75-85 per cent RH during fruiting; TNAU gives 80-85 per cent at 23-25 C. Raise it by spraying floor, walls and air two or three times a day and hanging wet gunny at windows.

Never leave water standing on caps; a water film in warm air lets bacteria spot and rot them.

Move air without blowing on the caps, which dries their edges. More air lowers RH, so spray again after venting.

Oyster needs light to form pinheads. The manual gives 200 lux for 8-12 hours a day; the folder asks for 6-8 hours from glazed windows or tube lights. A lux is a unit of light on a surface; 200 lux is a bright room, far below sunlight, and direct sun heats and dries bags.

Too little light looks like too much CO2: long stalk, small cap, poor yield. Below 100 lux the caps go pale yellowish; in very bright light they turn dark brown or grey. When you see long stalks, add air time first, then check light hours before blaming the spawn.

Twist the whole cluster off at the base before the cap edges flatten and curl; a flat cap is shedding spores and tears easily. The DMR folder adds a health rule: open doors and windows two hours before harvesting and wear a mask, because oyster spores cause allergy.

A flush is one wave of mushrooms. The folder says the first flush gives about half or more of the total, the second comes 8-10 days later, and three flushes are worth keeping; then the bags go to a deep pit.

The folder reports 700-800 g fresh mushroom per kg dry straw; the manual states a minimum of 500-700 kg per tonne in 45-60 days. Reports, not promises.

Fresh oyster keeps 24-48 hours at room temperature, so plan the sale before the pick. The folder's method: spread the mushrooms on a cloth for about two hours so surface water dries, then pack in perforated polythene; in a refrigerator they hold 2-4 days.

The DMR post-harvest bulletin specifies polythene under 100 gauge with holes giving about 5 per cent vent area. TNAU packs 200 g per bag for retail.

If you cannot sell fresh, dry. The manual says dried oyster at 2-4 per cent moisture keeps 3-4 months when sealed. Drying is a second product, not a rescue for spoiled mushrooms.

The DMR folder puts the cost of producing a kilogram of dhingri at 10-15 rupees. It is undated, from the early 2010s, and marked medium confidence. The 2011 manual's model assumes 70 per cent biological efficiency and a sale price of 50 rupees per kg. Use these to learn the shape of a budget, never as today's prices.

Your numbers come from your diary: straw, spawn, polythene, labour and power for one batch; kilograms sold, not picked; the price each buyer actually paid; kilograms thrown away. Divide cost by kilograms sold. The folder itself prints two cycle lengths, 45-60 days in its introduction and 40-50 in its economics, so measure yours.