Wet Spot / Sour Rot (Bacillus)

Grey, greasy, translucent patches in grain or substrate that mycelium refuses to cross; a sour, rotten smell.

Likely causes

• Under-sterilised or overly wet substrate
• Slow cooling

What to do

Dispose of it — this doesn't recover. Fix the sterilisation step and substrate moisture next time.

Easily confused with

• Bacterial Blotch (Pseudomonas)

Not sure?

Walk through the troubleshooting guide, ask the AI Grow Consultant, or check the conditions your species needs on its species page.

This entry is general growing guidance compiled from extension and trade practice; it has no single citation yet. Treat it as a starting point.

Last updated: 2026-10-19