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Black Pin Mold

Rhizopus / Mucor spp.

Fast-growing contamination that starts white/grey then develops black spherical spore heads. Can overtake a grain jar in 24-48 hours. Common on bread and grain substrates.

Reference Images

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What It Looks Like

Fast-spreading fuzzy white/grey mold with tiny black pin-like dots (sporangia) on top, looks like a forest of black-headed pins

Recommended Action

Dispose immediately. Do not open indoors as spores spread easily. Bag and discard. Review sterilization and filtration protocols.

How to Identify
  • 1Starts as white/grey fuzzy growth
  • 2Develops black spherical heads on stalks
  • 3Looks like tiny black pins or dots
  • 4Spreads extremely fast (24-48 hours)
  • 5Often appears on grain spawn
  • 6Has a musty smell
Common Causes
  • Insufficient sterilization time
  • Contaminated grain or substrate
  • Poor air filtration
  • Dirty hands, gloves, or tools
  • Working in dusty or moldy environment
Prevention Tips
  • Proper sterilization (full pressure cooker cycle)
  • Use HEPA filter or laminar flow hood
  • Maintain sterile technique
  • Store materials in clean, dry areas
  • Ensure good air filtration

Learn more from external sources:

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