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Mushroom Cultivation Troubleshooting
"Identify and resolve common issues with mycelial growth, fruiting stalls, and contamination."
Success in mycology often depends on your ability to read the mycelium and adjust environmental variables. This guide covers the most common failure points from spawning to bulk through harvest.
Objective: Diagnose growth stalls, identify competitors, and optimize environmental triggers to ensure a successful flush.
Phase 1: Growth & Colonization Issues
Before assuming contamination, verify that your temperature, hydration, and gas exchange are within the optimal parameters for your specific species.
- Stalled Mycelium: If growth stops abruptly, it is often due to moisture imbalance or CO2 buildup.
- Check Field Capacity: Substrate that is too wet suffocates mycelium. If the bottom of the tub looks "slushy," flip the lid to increase evaporation.
- Temperature Swings: Mycelium generates its own heat. If ambient temps exceed 80°F, the internal tub temp can reach levels that kill or stall growth.
- Overlay & Stroma: Dense, thick, leather-like white growth that refuses to pin.
- Cause: Usually caused by low humidity combined with excessive Fresh Air Exchange (FAE), or genetic predisposition.
- Fix: Lightly "fork" the surface to break the mat and apply a fresh, thin casing layer of pasteurized peat or CVG to re-induce a microclimate.
Phase 2: Environmental Indicators
| Symptom | Probable Cause | Corrective Action |
| Fuzzy Feet | High CO2 / Low FAE | Increase lid gap or fanning frequency. |
| Leggy/Thin Stems | Low Light / High CO2 | Increase light exposure and air exchange. |
| Mushroom Aborts | Stress / Dry Surface | Remove small, dark-capped pins; mist walls immediately. |
| Yellow Droplets | Metabolites ("Pee") | Mycelium is stressed or fighting bacteria. Check temps. |
- Aborts: Recognized by pins that stop growing and develop dark, often pointed caps.
- Prevention: Avoid direct spraying of young pins. Maintain a "cold soda can" level of condensation on the tub walls at all times.
- Fuzzy Feet/Caps: Fine white fuzz at the base or white dots on the caps.
- Insight: This is not contamination; it is the mycelium "reaching" for oxygen. It is the most common indicator that your FAE is insufficient.
Phase 3: Contamination Management
If you suspect contamination, isolate the tub from your grow space immediately to prevent spore load buildup.
- Trichoderma (Green Mold): Starts as a bright, thick white patch (whiter than mycelium) before turning green as it sporulates. Action: If it’s green, the tub is lost. Do not open it indoors.
- Cobweb Mold: Fast-growing, gray, wispy fibers that "hover" above the substrate.
- The Peroxide Test: Spray with 3% $H_2O_2$. Cobweb will melt instantly; healthy mycelium will not.
- Bacterial Blobs/Sour Rot: Characterized by a "sweaty" appearance on grains and a distinct sour or fermented odor.
- Cause: Usually improper grain sterilization or over-hydrated substrate.
Pro-Tips for Commercial Scalability
- Repeatable Cleanliness: Transition from a Still Air Box (SAB) to a HEPA-filtered Laminar Flow Hood as soon as volume demands it.
- Documentation: Use a "Project State" rule to log the date of spawn, substrate ratios, and the date of first pins to identify which variables yield the highest Biological Efficiency (BE).