Describe the change
Coarse, hairlike fungal growth on caps.
Fungal diseases
Syzygites cap mould
Hairlike growth on mushrooms can be mistaken for cobweb. The cap tissue and the stage at which the growth appeared both matter.
Organism / cause: Syzygites megalocarpus
Where this evidence applies: Reported in Agaricus crops and after harvest.
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
Cobweb, Mucor/Rhizopus and normal surface mycelium.
Collect one useful piece of evidence
Establish whether symptoms began before harvest, in packing or during storage.
A visual match is only a starting point. Specialist microscopy distinguishes this fungus from superficially similar growth.
01 · Observe
What you may see
- Coarse, hairlike fungal growth on caps.
- Changing yellowish to grey/green growth with damage to underlying tissue is described in extension guidance.
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
- Cobweb, Mucor/Rhizopus and normal surface mycelium.
- A postharvest contaminant that was not present in the growing room.
How it may arise or move
Affected mushrooms and contaminated crop debris can support further fungal growth; handling can carry material between locations.
03 · Check
Collect evidence before changing the crop
- Establish whether symptoms began before harvest, in packing or during storage.
- Photograph intact growth from the side as well as above.
What confirmation needs: Specialist microscopy distinguishes this fungus from superficially similar growth.
Use the field record and sampling checklist →04 · Respond
What to do next
- Separate affected produce from saleable lots pending assessment.
- Do not brush off the growth and return the mushroom to sale.
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
- Inspect crop and packing areas separately.
- Remove crop debris through a contained waste route and maintain suitable postharvest conditions.
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 disease account; photographs alone are not confirmation.
- Basic IPM: Syzygites Disease on the Agaricus Mushroom ↗
Penn State Extension · 8 July 2021
Used for: Hairlike growth, cap damage and postharvest occurrence.
Limit: Do not identify Syzygites from a fuzzy photograph alone.
Compare related explanations
Fungal diseases
Cobweb disease
Spreading surface growth can overrun casing and fruit bodies. The important clue is progression across the crop, not simply white colour.
Strong Agaricus evidence; additional cultivated hosts are documented in Korean studies. Susceptibility varies with isolate and host.
Signs, checks & response →Competitor moulds
Mucor/Rhizopus-like pin mould and wet-substrate growth
Upright fuzzy growth with tiny dark heads is an observation to record, not a reliable species identification.
Generic contamination differential, not a proven host disease on all crops.
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 →