Describe the change
Growth stops and mushrooms become dry, leathery or spongy.
Bacterial diseases
Mummy disease / leathery stunted mushrooms
Mummy describes a recognisable crop syndrome, but the label should not hide uncertainty about cause.
Organism / cause: Bacterial associations described; a unique universal cause is not established here
Where this evidence applies: Agaricus production syndrome.
Picture → observation → next check
A visual guide to your observations
- Cap surface
Record a local spot versus whole-cap colour, and whether it was present before picking.
- Gills underneath
Separate normal maturity-related pigmentation from unusual wetness, exudate or deterioration.
- Inside the stem
Internal changes can differ from the outside. Obtain sampling instructions before cutting suspect material.
- Casing and compost
Note whether the change starts in the fruit body, the casing surface or the substrate below.
Keep another explanation open
Severe drying, root-zone damage and other causes of stalled growth.
Collect one useful piece of evidence
Map the direction and timing of the affected area.
A visual match is only a starting point. A crop-health specialist should evaluate the syndrome, process records and samples together.
01 · Observe
What you may see
- Growth stops and mushrooms become dry, leathery or spongy.
- Curved stems or longitudinal streaking can occur; affected mushrooms may remain firmly attached.
No verified reusable diagnostic photograph is included for this entry. The illustration above explains observation context, not a confirmed disease specimen. Consult the original source figures where available.
02 · Compare
What can look similar
- Severe drying, root-zone damage and other causes of stalled growth.
- Virus-associated abnormalities.
How it may arise or move
Room progression and compost condition matter; dense or overly wet compost and conditioning history deserve review.
03 · Check
Collect evidence before changing the crop
- Map the direction and timing of the affected area.
- Review compost condition, phase-II records and unaffected comparison beds.
What confirmation needs: A crop-health specialist should evaluate the syndrome, process records and samples together.
Use the field record and sampling checklist →04 · Respond
What to do next
- Avoid treating a provisional mummy label as proof of one bacterium.
- Seek advice before disruptive interventions such as bed trenching or removal.
These are investigation and containment steps, not a guaranteed cure. Do not eat, sell or distribute suspect material on the strength of a visual match. Do not culture unknown contaminants or experiment with pesticides in a growing room.
05 · Learn
Reduce recurrence
- Maintain suitable compost preparation and handling.
- Prevent movement of contaminated crop material into young rooms.
After intervention, compare new affected units, crop condition and inspection results against the same recorded baseline. A lack of visible growth does not, by itself, verify decontamination or food safety.
Read the stage-by-stage prevention plan →Evidence & sources
Extension synthesis; causal uncertainty is retained rather than replaced with a false precise name.
- Basic IPM: Bacterial and Viral Diseases of Mushrooms ↗
Penn State Extension · 8 July 2021
Used for: Mummy and La France recognition and exclusion.
Limit: Symptoms overlap with stress. Broad historical bacterial attribution does not establish a unique mummy pathogen.
- Seeding Substrate and Management of Growing Agaricus bisporus ↗
Penn State Extension · 23 December 2025
Used for: Spawn run, substrate heat, moisture and mummy-risk context.
Limit: Agaricus substrate management is not a sterilisation protocol for supplemented sawdust bags.
Compare related explanations
Viruses & culture health
La France virus disease
Poor cropping and malformed mushrooms can justify virus testing, but neither an image nor a low yield confirms a virus.
Agaricus virus investigation; symptoms are not specific.
Signs, checks & response →Environmental disorders
Condensation, wet caps, dry edges and cracking
Room humidity does not tell the whole water story. A crop can have wet caps in one rack zone and drying injury in another.
All production systems, with different crop-specific tolerances.
Signs, checks & response →Environmental disorders
Ammonia, waterlogging and unsuitable substrate
Poorly colonised substrate can be a process failure before a competitor arrives. Treating the visible late mould may miss the original cause.
Ammonia/conditioning is especially relevant to button compost. Bag substrates use different preparation systems.
Signs, checks & response →