Describe the change
Brown, necrotic tissue inside a cut stem.
Bacterial diseases
Internal stipe necrosis
A mushroom can look relatively normal outside while its stem is damaged internally. Internal quality checks can reveal a different problem from cap blotch.
Organism / cause: Ewingella americana in confirmed reports
Where this evidence applies: Reported in cultivated Agaricus; stem browning has multiple possible causes.
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
Mechanical injury, ageing and other internal rots.
Collect one useful piece of evidence
Record the proportion affected in a defined, documented sample.
A visual match is only a starting point. Published cases used isolation and pathogenicity tests; internal browning alone is not an Ewingella diagnosis.
01 · Observe
What you may see
- Brown, necrotic tissue inside a cut stem.
- External symptoms may be less obvious than the internal lesion.
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
- Mechanical injury, ageing and other internal rots.
How it may arise or move
Do not infer the route from a cut stem. Trace crop, picking and packing lots and discuss possible sources with the laboratory.
03 · Check
Collect evidence before changing the crop
- Record the proportion affected in a defined, documented sample.
- Keep separate photographs of external appearance and internal tissue.
What confirmation needs: Published cases used isolation and pathogenicity tests; internal browning alone is not an Ewingella diagnosis.
Use the field record and sampling checklist →04 · Respond
What to do next
- Hold affected produce and use clean sampling tools.
- Do not let the inspection knife spread material through saleable stock.
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
- Include internal quality in a proportionate inspection plan.
- Keep harvest and packing records linked to rooms and dates.
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
Primary disease report from Korea; not evidence of prevalence in India.
- Occurrence of Internal Stipe Necrosis of Cultivated Mushrooms Caused by Ewingella americana in Korea ↗
Mycobiology · 2009
Used for: Internal browning confirmed by isolation and pathogenicity tests.
Limit: A country-specific report; external appearance can miss internal damage. No figures reused under its restricted licence.
Compare related explanations
Bacterial diseases
Bacterial soft rot and tissue collapse
Wet, collapsing tissue is a reason to separate produce and investigate timing. It can be a primary infection or secondary decay after injury.
Symptom differential. The cited Burkholderia evidence includes Agaricus bitorquis; it is not the cause of every soft rot on this crop list.
Signs, checks & response →Food & worker safety
Postharvest spoilage, bruising and ageing
Separate when damage started from when someone noticed it. That distinction prevents a storage problem being mislabelled as a growing-room disease.
Harvest, packing, transport and storage; a crop can deteriorate after leaving a healthy room.
Signs, checks & response →