MushroomFarming / disease

Mushroom Disease Library

An evidence-led guide to separate symptoms, causal agents, disease development, differential diagnosis and confirmation.

Practical explanation + detailed referenceSources & review ↓

Cultivation context—not a diagnostic photograph. See the labelled symptom references below.MarvinBikolano · CC BY-SA 4.0View full photograph ↗

On this pageChoose a section, or keep reading below

Read this in the full guide: Investigate a crop problem without losing the evidence →

Understand the topic

What you need to know.

This library sorts mushroom diseases into the groups the ICAR-DMR manual uses: fungal diseases, competitor moulds, bacterial diseases, virus diseases and abiotic disorders. Each group tends to leave its own pattern and points to a different check. Use this page to decide which group fits your evidence and which sub-page to open next, not to name a disease from a picture.

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

Part 01

Five groups, and the pattern each tends to leave

The ICAR-DMR manual sorts crop diseases into five groups. Each tends to appear at a different point in the crop and to leave a different pattern.

Competitor moulds grow in the compost, casing or substrate and compete with the mushroom mycelium for space and food. They usually show first, during spawn run or on newly cased beds, and often across a whole batch, because many follow a fault in composting or pasteurisation.

Fungal diseases attack the mushroom itself. Dry bubble's whitish growth can appear on the casing; wet bubble, dry bubble and cobweb then deform or rot mushrooms in a patch that grows outwards through casing, water splash, hands and tools. The manual notes dry bubble becomes more common when cropping runs beyond two months.

Bacterial blotch, the most important bacterial disease of button mushroom, follows water: spots develop on caps that stay wet in a warm room, so its pattern tracks watering, condensation and airflow.

Virus disease is the hardest to see. The manual names die-back as the most serious in button mushroom, with highly variable symptoms, and says delayed pinheads in the first flush can be an important sign. Viruses pass on through mycelium and spores.

Abiotic disorders have no organism behind them. The manual traces them to conditions such as fumes, fast dry air, water stress and wet casing over dry compost; weepers, for example, appear before and during the first break.

Source: ICAR-DMR manual, 2011

When each group tends to show in a button crop

Spawn runCompetitor moulds such as ink caps and green mould show in the compost, often across a batch.
After casingMould growth, and the whitish growth of dry bubble, can appear on the casing surface.
First flushDelayed pinheads can signal die-back virus; weepers appear before and during the first break.
CroppingBubble diseases and cobweb deform or rot mushrooms in growing patches; blotch spots form on caps that stay wet.
Long cropsDry bubble grows more common in crops run past two months.

Part 02

Fungal diseases as the ICAR-DMR manual describes them

These descriptions help you compare, not identify. Other causes can produce similar shapes, and a specialist or laboratory confirms the organism.

Wet bubble: infection before cap and stem separate gives shapeless masses; later infection gives thick stems and deformed gills. Rotting tissue carries white mouldy growth, a golden brown liquid and a foul smell.
Dry bubble: whitish growth on the casing that turns greyish yellow. Early infection gives onion-shaped mushrooms and later infection crooked stems and tilted caps; mature caps get light brown sunken spots that join into dry, leathery, cracked blotches.
Cobweb: small white patches on the casing spread to nearby mushrooms as a fine grey-white growth, which may turn pink or red with age, and the mushroom finally rots.
Green mould: a dense, pure white growth that looks like mushroom mycelium and turns green as it forms spores. Mushrooms near it may brown, crack and show peeling stems.

Source: ICAR-DMR manual, 2011

Part 03

Competitor moulds usually point back to a process step

The manual's table of moulds reads like a checklist for compost and casing. Each mould is listed with the fault that usually lets it in.

Olive green mould follows poor aeration during Phase II, or pasteurisation above 60 °C. Ink caps follow ammonia or too much nitrogen in the compost, old wheat straw or too much moisture. Brown plaster mould follows poor, old straw, wet compost, high temperature or too little gypsum. Cinnamon mould follows casing that is too wet or strongly disinfected. White plaster mould is linked to high compost pH, green mould to low pH and immature spawn, and false truffle to poor pasteurisation and a hot spawn run.

For oyster mushroom the manual makes the same point: most competitor moulds come from lapses in pasteurisation, incubation temperature, bag size, substrate pH or hygiene, or from keeping a crop too long in heat.

So after a mould appears, the useful question is not which spray to buy but which step in the batch record was out of range. That step is what you change for the next batch.

Source: ICAR-DMR manual, 2011

Close view of two plastic substrate bags; one is streaked dark green and grey, the other is brown with pale growth. — Two sawdust substrate bags on a farm in Malaysia; the left one is streaked dark green where white mycelium would be expected. The mould has not been identified, and more than one mould turns green. Photo: Arne Müseler, CC BY-SA 3.0 DE. Source

Part 04

Figures that tell you how far back to look

A sign you see today began days earlier, and some sources of infection survive for years. These figures come from the disease chapter of the ICAR-DMR manual.

Dry bubble, infection to distorted mushrooms10 daysAt 20 °C.

Dry bubble, infection to cap spots3 to 4 daysAt 20 °C.

Dry bubble left uncontrolled can destroy a crop in2 to 3 weeks

Wet bubble resting spores survive in casing soilup to 3 yearsCasing is the main route in.

Dry bubble spores survive in moist soilone year

Cobweb causes most loss at19 to 22 °CWith high humidity.

Source: ICAR-DMR manual, 2011

Part 05

Deciding which group fits your evidence

Use the pattern and the room conditions together. Each rule starts from what you can see and points to a check, not to a final answer.

IfSlimy brown spots appear on caps that stay wet after watering, in a warm and humid room.: ThenLook at bacterial blotch and at the room first. The manual advises avoiding temperatures above 20 °C with humidity above 85 percent, airing after watering so caps dry, and avoiding temperature swings that cause condensation.
IfA white or coloured growth appears in compost or casing before any mushroom is affected.: ThenTreat it as a competitor mould first and pull the composting, pasteurisation and casing records for that batch.
IfDeformed mushrooms appear in a patch that grows outwards from a point.: ThenSuspect a fungal disease, contain the patch and ask for identification before any treatment; wet bubble and dry bubble are handled differently.
IfPinning is delayed, pins form under the casing, caps open early or drumsticks appear, and room readings are normal.: ThenConsider a virus only after carbon dioxide and temperature have been ruled out, and ask for laboratory testing, because the manual says die-back symptoms vary widely.
IfMushrooms weep water, show scales, lumpy rose-comb gills or hollow stems, with no spreading patch.: ThenLook for a disorder. The manual links weepers to compost below 64 percent moisture under wet casing, scales to fast air with low humidity, rose comb to fumes from kerosene, petrol, diesel or paint, and hollow core to water stress.

Sources: ICAR-DMR manual, 2011 · NHB DPR model, 2018

Part 06

Mistakes that carry one outbreak into the next crop

Common mistakeReusing casing soil from an affected crop, or using untreated soil.

Do this insteadUse treated casing every time. Wet bubble resting spores can survive for years in casing soil, and dry bubble reaches farms on infected casing.

Common mistakeDropping cut stems and spoiled mushrooms on the bed or floor.

Do this insteadCollect picking waste as you go and take it out; the manual says dropped stem cuttings encourage unwanted organisms.

Common mistakeEmptying an affected room straight after the last flush.

Do this insteadCook out the compost first. The NHB model DPR holds compost at 70 °C for 12 hours at crop end to kill the pathogen's mycelium and spores.

Common mistakeWatering over a patch of affected mushrooms as if nothing had changed.

Do this insteadMark and contain the patch before routine watering. The manual names water splash as a way wet bubble and cobweb spread.

Common mistakeLeaving caps wet after watering.

Do this insteadIncrease ventilation and air movement after watering so the mushrooms dry quickly.

Sources: ICAR-DMR manual, 2011 · NHB DPR model, 2018

Keep exploring

Every part of this topic.

Choose the stage, material or decision you need to understand next.

Fungal Diseases

An evidence-led guide to compare true fungal disease with mushroom mycelium, competitor moulds and abiotic injury.

Bacterial Diseases

An evidence-led guide to connect bacterial symptoms to surface water, handling, environmental history and laboratory evidence.

Viral Diseases

An evidence-led guide to treat non-specific crop decline cautiously and make molecular confirmation explicit.

Competitor Moulds

An evidence-led guide to distinguish substrate competition from direct mushroom disease.

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

Disease

Mushroom Disease Library

An evidence-led guide to separate symptoms, causal agents, disease development, differential diagnosis and confirmation.

Evidence postureExternal specialist review not recordedNo single-photo diagnosisNo operational chemical doseEditorially published

Button mushroom · Photo reference and management

See the symptom. Check the cause. Act carefully.

Real research photographs with practical, nonchemical first steps. These examples come from published studies, not MushroomWale farms. Resemblance is a clue, not confirmation of disease in your crop.

01Observe the crop and record the pattern
02Limit transfer to clean areas
03Check the diagnosis and follow a response plan
04Review the next crop for recurrence

Dry bubble

Look for malformed mushrooms, split stems or wart-like growths. Later infection can appear as grey-brown cap spots; the appearance changes with crop stage.

What to do first: Mark the patch and do not pick out or handle dry bubbles. Avoid splashing exposed affected tissue. Have a trained supervisor contain the patch using the linked extension procedure.
Reduce the chance of recurrence: Keep casing, casing equipment and clean tools protected from contaminated dust and debris. Check fly control and movement of people between rooms.
What can look similar?: Wet bubble and other causes of spotting can look similar. A photograph cannot identify the pathogen; ask for specialist examination when the pattern is unclear.
What to record: Record when the first affected mushrooms appeared, their bed positions, watering history and whether new spots developed nearby.

Read the full condition guide →AHDB: dry bubble recognition and containment ↗Undated archived guidance; accessed 17 September 2026. International guidance: adapt with a qualified adviser for your Indian farm.

Wet bubble

Irregular swollen tissue, severely distorted mushrooms and amber droplets are useful clues. Decay can develop as affected tissue deteriorates.

What to do first: Mark the area and avoid splashing it. Once wet bubble is identified, trained staff can carefully enclose local affected material in a disposable bag, seal it and follow the farm's containment and disposal procedure.
Reduce the chance of recurrence: Protect casing and water supplies from soil, dust and crop debris. Keep clean equipment away from contaminated floors and spent material.
What can look similar?: Do not apply this removal approach to an unidentified bubble: dry bubble handling differs. Ask a crop-health specialist to distinguish them.
What to record: Record the casing lot, first affected location, water source, spread after watering and photographs before intervention.

Read the full condition guide →AHDB: wet bubble recognition and containment ↗Undated archived guidance; accessed 17 September 2026. International guidance: adapt with a qualified adviser for your Indian farm.

Research reference: white cottony growth spreading across mushrooms and casing, captioned as cobweb in Gea et al. Figure 1b. — **Published research photograph**Panel 1b, lower photograph. Display cropped; no symptom retouching.Gea, Navarro, Santos, Diánez & Carrasco (2021), Figure 1, Microorganisms 9:585 CC BY 4.0The publication identifies crop symptoms in the lower row; the upper row contains cultures. Only the crop photograph is shown here.

Cobweb disease

Watch for an expanding cottony surface growth across casing and mushrooms. Older growth may become powdery, with spotting or a pinkish tinge.

What to do first: Mark the patch before routine watering. Do not brush, blow or spray exposed growth. Arrange gentle containment by trained staff, following the extension procedure and the room's crop-management plan.
Reduce the chance of recurrence: Inspect before watering, control dust and crop debris, and clean equipment between rooms. Review how air movement and watering could carry material from an affected patch.
What can look similar?: Normal mushroom mycelium and other moulds may look white. Rate of spread, location and examination of samples matter more than colour alone.
What to record: Photograph the same marked area over time. Note nearby spotting, recent watering and which rooms shared tools or staff.

Read the full condition guide →AHDB: cobweb recognition and containment ↗Undated archived guidance; accessed 17 September 2026. International guidance: adapt with a qualified adviser for your Indian farm.

Research reference: green-sporulating growth in a Button mushroom crop, captioned as green mould in Gea et al. Figure 1d. — **Published research photograph**Panel 1d, lower photograph. Display cropped; no symptom retouching.Gea, Navarro, Santos, Diánez & Carrasco (2021), Figure 1, Microorganisms 9:585 CC BY 4.0The publication identifies crop symptoms in the lower row; the upper row contains cultures. Only the crop photograph is shown here.

Green mould observation

A dense white patch may later become green as spores form. Poor cropping can accompany the affected area, but colour does not identify a mould species.

What to do first: Flag the batch and restrict movement of affected material, tools and staff into clean areas. Do not shake bags or brush spores off beds. Obtain advice on containment and whether the crop should continue.
Reduce the chance of recurrence: Review compost preparation, spawning hygiene and batch history together. Check cleaning and the validated end-of-crop treatment before loading another crop.
What can look similar?: Several moulds can appear green. Laboratory identification may be needed to establish whether Trichoderma is involved and which species it is.
What to record: Record whether growth is in compost, casing or surface debris, which input lots are shared, and whether other rooms from the same batch are affected.

Read the full condition guide →Penn State Extension: green mold of mushrooms ↗Updated 23 December 2025; accessed 17 September 2026. International guidance: adapt with a qualified adviser for your Indian farm.

Research reference: brown surface blotching on a naturally affected mature Button mushroom, Huang et al. Figure 1b. — **Published research photograph**Panel 1b, natural symptoms. Display cropped; no symptom retouching.Huang, Huang, Nie & Liu (2024), Figure 1b, Phytopathology Research 6:21 CC BY 4.0Panel b shows naturally affected mature Button mushrooms from the study in Guangxi, China, not an Indian farm or an inoculation experiment.

Bacterial blotch

Yellow-brown to dark brown superficial patches may occur on caps, including places where mushrooms touch or surfaces remain wet.

What to do first: Check actual cap wetness after watering and look for condensation. Correct water timing and air distribution with the crop supervisor so surfaces can dry without desiccating the crop.
Reduce the chance of recurrence: Avoid persistent wet surfaces, uncontrolled temperature swings and splash transfer. Clean handling equipment and compare conditions across the room, not only at the wall sensor.
What can look similar?: Bruising, fungal spots and other bacteria can produce browning. The photographed study found more than one bacterial cause; matching a picture is not a species diagnosis.
What to record: Note when spotting appears relative to watering, picking and packing. Record wetness, condensation and affected positions before changing settings.

Read the full condition guide →Penn State Extension: bacterial blotch disease ↗Updated 23 December 2025; accessed 17 September 2026. International guidance: adapt with a qualified adviser for your Indian farm.

From symptom to cause

A first look, not a diagnosis. Most signs have more than one possible cause. Source: ICAR-DMR manual 2011.

What you see	One common cause	First step
Long stems, small caps	CO₂ building up around the crop; poor air movement	Correct the air circulation; cropping CO₂ 800 to 1,000 ppm
Green patches on compost	Green mould; low compost pH, immature spawn	Isolate, remove; check the next batch
No pins after casing	Room not aired and cooled	Air at 15 to 17 °C, RH 85%, ventilate
Brown sunken spots on caps	Bacterial blotch; a water film on the caps	Manage humidity, temperature and air movement so caps dry
White wet lumps	Wet bubble; spores survive in casing soil	Cover with plastic cups; treat the next casing
Small flies	Sciarid or phorid flies	Screens, light traps, hygiene

Picture → explanation → field task

Keep clean and suspect work separate

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

Generated illustration of dedicated work footwear and a handwashing basin at a farm entrance.

Make clean entry a routine

Clean entry has a place and a repeatable sequence. Footwear, hands and movement between areas are part of farm hygiene. The illustration does not demonstrate a validated disinfection process.

Try this on your farm

Assign the entry routine, provide suitable facilities and check that visitors and workers follow it.

Generated illustration of raw straw separated from closed cultivation bags on a different bench.

Protect prepared material

Raw inputs and protected prepared material are separated. Treatment does not protect a substrate indefinitely. Handling afterwards can introduce contamination.

Try this on your farm

Keep work areas, tools and movement routes separated. Label batches so a later problem can be traced to its preparation history.

Generated illustration of two closed cultivation bags in a washable tray with dedicated tools.

Keep suspect bags closed

A separate tray helps identify material being held for investigation. The bags are illustrative and not diagnosed. Opening, shaking or smelling suspect material is not a confirmation method.

Try this on your farm

Mark the batch, limit movement and seek qualified advice on sampling or disposal. Do not return dedicated tools to clean work without the appropriate procedure.

Generated illustration of a covered waste tub leaving a separate area away from covered harvest crates.

Plan the spent-material route

Used material and saleable harvest follow different handling paths. A disposal route can undo clean-work separation if it crosses incoming materials or harvest handling.

Try this on your farm

Map the exit route and cleaning responsibility. Check the actual workflow during a busy room turnaround, not only on a drawing.

Disease development needs context

A pathogen finding alone does not describe the whole outbreak.

Susceptible hostSpecies, strain and crop stage

PathogenIdentity, inoculum and pathway

Favourable environmentWater, temperature, airflow and time

Disease developmentExpression depends on their interaction

Infectious or non-infectious?

These are tendencies, not absolute laws.

Infectious pattern may show

Progression over time
Localized spread
Characteristic signs
Recurrence through a pathway

Environmental pattern may show

Rack, layer or wall alignment
Correlation with airflow or sensors
Shared response to a control change
Rapid improvement after physical correction

Printable field sheet

Disease Incident Report

Use browser print

Farm and roomDate and crop stageRoom, rack, layer and positionObserved symptomPattern and progressionAir and compost measurementsWatering and chemical historyPest or trap evidencePossible causesEvidence still neededAction and outcome

Explore this system

Move from the hub to the most specific evidence record.

Disease

Fungal Diseases

An evidence-led guide to compare true fungal disease with mushroom mycelium, competitor moulds and abiotic injury.

Open resource Disease

Bacterial Diseases

An evidence-led guide to connect bacterial symptoms to surface water, handling, environmental history and laboratory evidence.

Open resource Disease

Viral Diseases

An evidence-led guide to treat non-specific crop decline cautiously and make molecular confirmation explicit.

Open resource Competitor mould

Competitor Moulds

An evidence-led guide to distinguish substrate competition from direct mushroom disease.

Open resource

Quick recognition

Use mushroom disease library to separate symptoms, causal agents, disease development, differential diagnosis and confirmation. Recognition begins the investigation; it does not confirm a cause.

Observe early, developing and advanced signs
Map distribution and progression
Compare biological and abiotic causes
Confirm before high-risk action

What to record

Capture crop stage, crop day, room, rack, layer, pattern, first observation, progression, compost and casing batches, watering, chemistry, pests and timestamped environmental readings.

Could it be something else?

Compare visual appearance with spatial pattern, progression, environmental history, process history and missing expected signs. Colour or one photograph is weak evidence.

Evidence still needed

State the unanswered questions and next measurement. Useful evidence can be visual, environmental, spatial, temporal, microscopic, laboratory, molecular, trap-based or process-history based.

Immediate safe direction

Document the affected area, avoid unnecessary disturbance or cross-room movement, isolate suspect tools, inspect adjacent areas and preserve representative evidence. Do not spray automatically.

Root-cause review

Trace the visible problem through water, evaporation, airflow, sensor placement, compost, casing, staff movement, flies, tools or room design where evidence supports the connection.

Chemical and regulatory boundary

Historical management literature is separated from current practice. No crop-protection dose is published unless the exact product, formulation, mushroom crop label, target, method, harvest interval, worker-safety information and current Indian status are verified.

When remote guidance is inadequate

Seek technical inspection or laboratory support for rapid unexplained loss, repeated outbreaks, suspected virus, unknown mould, severe pests, chemical injury, multiple affected rooms or unresolved contradictions.

Evidence and review

Trace the claim and its limits.

Pathogen biology, dated advisories and current regulatory status are stored separately.

Institutional Reference

Diseases and Competitor Moulds of Mushrooms and their Management

Indian mushroom disease descriptions, symptoms, epidemiology, historical taxonomy and competitor-mould records.

Open source

Institutional Reference

ICAR-DMR Technical Bulletin Library

Institutional publication index for disease, farm-design, post-harvest and spent-substrate references.

Open source

Institutional Reference

Fungal diseases of mushrooms and their control

Dry bubble, wet bubble and cobweb symptom progression and hygiene pathways.

Open source

Institutional Reference

Directorate of Plant Protection, Quarantine and Storage regulatory functions

Indian pesticide registration and regulatory-governance context under the Insecticides Act and Rules.

Open source

Chemical governance is a publication gate.

No operational pesticide, fungicide, insecticide, disinfectant or fumigant dose is published. Historical references are not current labels.

Current operational dose: Not published
Mushroom crop label: Not established by this record
Review status: Regulatory review required

Read the evidence

Sources & review.

Editorial update: 2026-08-23. Independent technical review is not recorded for this entry.

Diseases and Competitor Moulds of Mushrooms and their Management ↗
ICAR-Directorate of Mushroom Research · 2007
ICAR-DMR Technical Bulletin Library ↗
ICAR-Directorate of Mushroom Research
Fungal diseases of mushrooms and their control ↗
Teagasc · 2015
Directorate of Plant Protection, Quarantine and Storage regulatory functions ↗
Directorate of Plant Protection, Quarantine and Storage · 2024

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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