Cobweb mold

Cobweb mold, caused by fungi of the genus Cladobotryum, is one of the most destructive diseases in commercial mushroom production. It is a mycoparasite that specifically targets mushroom mycelium and fruiting bodies, leading to rapid degradation and complete loss of crop quality if left unmanaged.

The pathogen spreads primarily through airborne conidia. Because these spores are microscopic and lightweight, they can easily travel across a growing facility via ventilation systems. Furthermore, human activity, contaminated equipment, and infestations of sciarid or phorid flies act as major vectors for the pathogen’s spread throughout the growing room.

Symptoms are easily identifiable as a fluffy, white mycelial growth that spreads rapidly across the casing soil. As the disease progresses, it covers the mushrooms with a web-like appearance. The infected fruiting bodies eventually become distorted, turn soft and brown, and finally decompose into a slimy, foul-smelling mass.

The development of Cladobotryum is heavily influenced by the environment. High relative humidity (often exceeding 90%), poor air circulation, and warm temperatures create a perfect environment for the mold to flourish. Excess water remaining on the casing surface after irrigation is a primary trigger for an outbreak.

Effective management requires a proactive approach to farm hygiene and environmental control:

• strict sanitation protocols for tools and work surfaces;
• implementation of effective fly control measures;
• monitoring humidity levels to avoid condensation on caps;
• spot-treating infected areas with salt or approved disinfectants to prevent sporulation;
• maintaining rigorous air circulation to promote a drier surface environment.