MushroomFarming / guide

Case run

Follow mycelial development into casing while protecting structure, moisture and uniformity.

Practical explanation + detailed referenceSources & review ↓

Real cultivation photograph. Read its source for location and context; it is not a universal operating specification.Pavimps · CC BY-SA 4.0View full photograph ↗

On this pageChoose a section, or keep reading below

Read this in the full guide: Run a Button mushroom crop from receipt to room reset →

Understand the topic

What you need to know.

Case run is the week or so after casing when mycelium grows up from the compost into the casing layer. The casing page explains the layer and how to lay it. This page goes further into the week itself: the two ICAR-DMR descriptions of the room, how to read the layer, how to water it, the airing schedules for the switch to fruiting, and how to choose between them.

Teaching revised 2026-09-24. Source-linked editorial synthesis; this date does not imply independent technical review.

Part 01

The case-run room, as two ICAR-DMR sections describe it

The manual describes case run twice, and the two passages differ in detail. The agronomy section gives one set of figures; the environment section keeps the spawn-run settings going. Both want warm, humid, closed air that keeps mycelium spreading. Pick one set, write it on the room sheet, and keep to it.

Temperature24 plus or minus 1 °CAgronomy section. The environment section gives air at 23 plus or minus 1 °C and the bed at 24 to 25 °C.

Relative humidity95 %Both sections.

Carbon dioxideabove 7500 ppmAgronomy section. The environment section keeps it as in spawn run, which the same chapter puts at 10000 to 15000 ppm.

Fresh airnoneThe manual says no fresh air is needed during case run.

Durationabout 7 daysBoth sections; the end is set by the layer, not the date.

Seasonal room22 to 25 °CThe ICAR-DMR button folder, with 80 to 90 percent humidity and a daily moisture check.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · ICAR-DMR button folder

Part 02

Reading the casing layer before you change the room

From about the fifth day, look at the layer daily at the same marked spots: near the door, in the middle and at the far end. Write down what you see and where. High carbon dioxide this week is expected; the manual notes it actually peaks during case run. The layer can show any of the following.

Mycelium showing in the valleys, the low areas between the peaks of the casing, across the whole bed: case run is complete.
Mycelium in the valleys at one end only: note the casing depth there, the watering record and the position before deciding anything.
Mycelium that hardly enters the casing, or fades after spreading: the manual lists this among the signs of die back, a virus disease. Record it and ask for a diagnosis.
Dense white patches that peel off the casing surface: stroma. The NHB report says stroma on casing rots quickly once watering begins.
Large round patches of white growth turning golden, then cinnamon brown: cinnamon mould, which the manual links to casing that is too wet.
Cream-white wefts where compost meets casing: false truffle is most conspicuous at that junction and on the casing.
Slender bell-shaped mushrooms in a newly cased bed: ink caps, a sign that ammonia remained in the compost.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · NHB DPR model, 2018

White button mushrooms in the corner of the frame with white thread-like mycelium running through dark growing medium. — White mycelium threads running through a dark growing medium, with young button mushrooms at the edge of the frame. In case run these are the threads you look for in the casing valleys. Photo: Ірина Бучнєва, CC BY 4.0. Source

Part 03

Watering the layer through case run

During case run the mycelium draws water from both the compost and the casing. The aim is a layer that is evenly damp when fresh air comes in, without wetting the compost below it.

Check every dayLift a pinch of casing from three places on each marked bed. It should be damp all through, not wet on top and dry below. The button folder checks moisture in the bags daily and sprays as needed.
Spray little and oftenGive light sprays in rounds rather than one heavy watering, so that no water runs through into the compost.
Never let the surface dryDried casing seals into a mat that no longer takes up water, and the manual reports heavy crop losses from it.
Do not overdo it eitherThe manual links casing that is too wet with cinnamon mould. The NHB report sees weeping mushrooms where wet casing sits on compost with less than 64 percent moisture.
Ruffle, if you use the practiceSome growers ruffle the casing 3 to 4 days after casing to get more even pinning.
Arrive at venting chargedThe casing should be wet enough at the moment fresh air comes in and the room is cooled. The manual's target at pinning is about 50 plus or minus 2 percent moisture.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · ICAR-DMR button folder · NHB DPR model, 2018

One watering round in case run

FeelA pinch of casing from three places on each marked bed.
Spray lightlyOnly where the layer is drying, in light rounds.
Wait and recheckNo water should reach the compost below.
RecordDate, time and quantity of every watering.

Part 04

The three airing schedules ICAR-DMR gives for the switch

The manual calls venting after case run a critical phase, and says that whether to cool first or bring in fresh air first is a question that troubles commercial growers. It answers with three schedules, chosen by the flush pattern you want.

Soft airing: air19 then 17 °C19 °C within 48 hours and 17 °C within 72 hours; compost 21 °C within 96 hours.

Soft airing: carbon dioxide and humidity4000 down to 1000 ppm4000 ppm in 48 hours, 2000 ppm over the next 24, 1000 ppm after 72 hours; humidity 98 to 92 percent in 48 hours.

Moderate airingbelow 1000 ppm within 48 hours2000 to 2500 ppm within 24 hours; compost 20 °C within 72 hours; humidity 98 to 92 percent in 24 hours.

Severe airing: air15 °C as soon as possibleCompost 20 °C within 48 hours.

Severe airing: carbon dioxide and humiditybelow 1000 ppm within 12 hoursHumidity 98 to 90 percent in 12 hours.

Source: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption

Part 05

Deciding when to vent, and how hard

The venting decision has two parts: whether the layer is ready, and which schedule suits your crop and your buyers.

IfMycelium shows in the valleys across the whole bed.: ThenThe layer is ready. Start the schedule you have chosen and record the day and hour.
IfOnly part of the bed is ready.: ThenFind the reason first: casing depth, water and position. Venting early leaves mycelium short of the surface, and pinning is thin and late.
IfYou need steady picking to match daily market demand.: ThenSoft airing restricts venting to give smaller flushes suited to the market; moderate airing gives well-spaced flushes of moderate size.
IfYou want as much as possible in the first flush.: ThenSevere airing puts no limit on fresh air. The manual expects a heavy pin set and a large first flush, followed by smaller flushes.
IfYour room cannot be cooled quickly, as in seasonal growing.: ThenFollow the button folder: after about a week of case run, bring the room down from 22 to 25 °C to 16 to 18 °C, and open doors and windows for a while every morning and evening.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · ICAR-DMR button folder

Part 06

Mistakes in the week after casing

Common mistakeTreating a high carbon dioxide reading in case run as a fault and opening the vents.

Do this insteadKeep the room closed until the layer is ready. The manual wants carbon dioxide high during case run.

Common mistakeLetting the casing dry while waiting for the mycelium.

Do this insteadKeep the layer evenly damp. A dry layer seals and stops taking up water.

Common mistakeWatering heavily to catch up after a dry spell.

Do this insteadCatch up in several light rounds. A heavy dose runs into the compost or leaves the casing too wet.

Common mistakeTreating a strange patch with a fungicide on a guess.

Do this insteadRecord it and ask for a diagnosis. Die back, false truffle, cinnamon mould and stroma can all show in the layer, and each needs a different response.

Common mistakeVenting without deciding on a schedule.

Do this insteadChoose soft, moderate or severe airing before you start, and write the targets on the room sheet.

Source: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption

Go deeper

Technical reference, records and tools.

Detailed crop-stage information, parameters, diagrams and specialist tools are kept together below. This material retains its source conditions and review limits.

Open the complete technical reference

Button Mushroom · cultivation stage

Case run

Agaricus bisporus

Follow mycelial development into casing while protecting structure, moisture and uniformity.

Publication: Public editorial page
External review: Not yet recorded · needed from Button Mushroom technical reviewer
Updated: 2026-08-22
Evidence records: 2

A few button mushrooms and pinheads emerging from black casing soil in compost bags, Tamil Nadu (uploaded by a TNAU student); dim and slightly soft. — Button mushrooms on casing soil in compost bags. Photo: Pavimps, CC BY-SA 4.0. Source

Button mushroom crop cycle

CompostDay 0Pasteurised, ammonia below 10 ppm
Spawn run12-14 daysAir 23 ± 1 °C, RH 95%
CasingDay 153-4 cm layer, pH 7-7.5
Case runAbout a weekMycelium reaches the casing valleys
Pinning3-4 daysAir to 15-17 °C, RH 85%, fresh air in
FlushesFlush by flushAir 15-17 °C, RH 80-85%

Picture → explanation → field task

A crop-room round

AI-generated educational illustrations. Not actual farm photographs, diagnostic evidence or construction specifications.

Generated illustration of gentle water application to a bare casing surface before mushrooms emerge.

Assess casing before watering

This scene shows casing without developing fruit bodies. Water needs depend on stage and material condition. The picture does not specify a quantity or a universal watering schedule.

Try this on your farm

Check the approved crop protocol and the actual casing condition before deciding how much to apply. Record the application.

Generated illustration of a grower recording different pin densities along mushroom beds.

Compare the pinning pattern

The bed does not develop uniformly at every position. Differences can involve inputs, water or room conditions. A patch is an observation, not a diagnosis.

Try this on your farm

Compare fixed locations over successive rounds. Photograph the same patch and record nearby readings before changing settings.

Stage11

Crop-stage dashboard

Case run

Biological state: Mycelium develops through the casing interface
Operator objective: Create uniform biological readiness for initiation
Handoff: Begin pinning transition from mapped crop readiness

ObserveDevelopment patternmoisturesurface structure

Depends onCasing qualitywater historycompost condition

Quick orientation

Case run is a transition at the compost-casing boundary. Observations should describe spatial pattern, depth and crop history rather than relying on surface whiteness as a single readiness test.

System role

Case run links casing application with the later environmental transition into pinning.

What to observe

Build a record before making a change.

Mycelial distribution into casing
Moisture through depth
Surface and subsurface structure
Zone-to-zone differences

Decision framework

Use the observation to narrow a decision, then verify the response.

Protect or correct uniformity
Time interventions by crop response
Avoid sealing the surface
Prepare a deliberate pinning transition

Dependencies and handoffs

This topic cannot be interpreted in isolation.

Casing application
Water history
Compost activity
Room climate
Hygiene

Practical layer

Start in the room with mycelial distribution into casing and moisture through depth. Record location, stage and recent events before changing the process.

Technical layer

The technical model joins casing application, water history, compost activity. Any operating value must be attached to a registered parameter, measurement location and applicable condition.

Evidence boundary

This page is grounded in: Physicochemical characterization of casing materials used in Button Mushroom cultivation; Mushroom Cultivation, Marketing and Consumption. Source provenance does not remove the need to check stage, system, date and local applicability.

Progressive depth

Go deeper without losing the field question.

PracticalWhat to notice in the room

Mycelial distribution into casing
Moisture through depth
Surface and subsurface structure
Zone-to-zone differences

TechnicalHow the interacting system is interpreted

Casing application
Water history
Compost activity
Room climate
Hygiene

ResearchWhich evidence records govern this page

ICAR-MR-CASING-2025
ICAR-DMR-CULTIVATION-MANUAL

Technical registry

The numbers for this stage, with their source.

Values are published from ICAR-DMR guidance with the stage and measuring point they apply to. A parameter still marked pending has no published Indian value yet.

BUTTON.CASING.MOISTURE_STATUS

Casing moisture at pinning

48 to 52 % moisture

ICAR-DMR gives 48 to 52 percent casing moisture at pinning; the layer itself is 3 to 4 cm deep.

Stage: Casing and case run
Measured at: Representative depth through the casing layer
Crop meaning: Water availability at the crop surface when pins form.
Applicable conditions: Casing material; Depth; Sampling method

published sourced

BUTTON.CLIMATE.COMPOST_TEMPERATURE

Compost temperature

20 to 25 °C

24 to 25 °C during spawn run, easing to about 20 °C once the room is aired for pinning.

Stage: Colonisation and cropping
Measured at: Within compost at defined bed positions
Crop meaning: Crop heat, which can sit above room-air readings.
Applicable conditions: Stage; Crop load; Probe placement

published sourced

Evidence and review record2 mapped sources

Sources support the page architecture and conceptual guidance. Technical values remain governed separately in the Button registry.

Tier C · research

Physicochemical characterization of casing materials used in Button Mushroom cultivation

Casing function and material-characterization context. Trial findings remain bounded to the study design.

Accessed: 2026-08-22
Publisher: Mushroom Research, ICAR

Open original source

Tier A · foundational

Mushroom Cultivation, Marketing and Consumption

Broad cultivation, post-harvest and market context. Values are not promoted without page-level review.

Accessed: 2026-08-22
Publisher: ICAR-Directorate of Mushroom Research

Open original source

Read the evidence

Sources & review.

Editorial update: 2026-08-22. Independent technical review is not recorded for this entry.

Physicochemical characterization of casing materials used in Button Mushroom cultivation ↗
Mushroom Research, ICAR · 2025
Mushroom Cultivation, Marketing and Consumption ↗
ICAR-Directorate of Mushroom Research

Reading a source is not the same as applying its instructions to every farm. Confirm species, strain, crop stage, system, region and publication date. Old chemical recommendations are not current-use instructions.

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