Verticillium dry bubble

Lecanicillium fungicola is a serious fungal pathogen that causes a disease commonly known in the mushroom industry as dry bubble or Verticillium disease. It primarily affects the cultivation of Agaricus bisporus (button mushroom), leading to significant yield losses and lower product quality.

The fungus is soil-borne and can easily be introduced into mushroom houses via contaminated casing soil or infected compost. Furthermore, the spores can be spread rapidly through water splashes during irrigation, as well as by workers, farm tools, and sciarid flies that serve as efficient vectors for the pathogen.

Symptoms depend heavily on the timing of the infection. Early-stage infection typically results in severely deformed, irregular mushroom heads that develop thick, fleshy, bubble-like structures. In later stages, affected mushrooms often develop light brown spots or show greyish, fuzzy mycelial growth on the surface.

Development is favored by warm and humid conditions within the mushroom house. High relative humidity and poor air circulation allow spores to germinate quickly and colonize the mushroom tissues. The fungus produces large quantities of conidia, which can survive in the environment for extended periods if hygiene is not strictly enforced.

Preventative and control measures are essential to maintain a healthy crop.

• Rigorous sanitation practices and disinfection of all facilities
• Use of disease-free casing materials
• Effective control of pest populations, particularly mushroom flies
• Monitoring and maintaining optimal temperature and humidity levels
• Immediate removal and safe disposal of any infected mushroom clusters