Lecanicillium psalliotae

The most visible symptom is the appearance of a white or creamy, fluffy mycelial growth on the surface of the casing soil or the mushrooms themselves.

Initial signs consist of small, localized patches that expand quickly under high moisture levels, covering the substrate in a dense mat.

Infected fruiting bodies show clear signs of deformity, softening, and tissue decay, accompanied by the production of a white powdery spore mass.

The affected mushrooms emit an unpleasant odor and stop growing, making them completely unsalable and unsuitable for consumption.

• White, fluffy mycelial growth.
• Softening and decay of fruiting bodies.
• Visible powdery spore production.
• Stunted growth of the cultivated mushrooms.

Lecanicillium psalliotae is an entomopathogenic fungus belonging to the Cordycipitaceae family. While it is known for infecting insects, it is a significant nuisance in mushroom farming.

This pathogen acts as a competitor, colonizing the substrate and outcompeting the commercial mushroom mycelium for nutrients and space.

The fungus produces a large quantity of conidia, which are easily dispersed by air currents, facilitating rapid spread within mushroom production facilities.

Microbiologically, the pathogen is recognized by its verticillate conidiophores, which produce spores that thrive in high-humidity environments.

Persistence is a key feature, as the spores can survive on equipment and building structures, making it difficult to eradicate completely.

High relative humidity, typically exceeding 85 to 90 percent, is the primary driver for the development and spread of this fungal disease.

The pathogen prefers moderate temperatures, usually ranging from 20 to 25 degrees Celsius, which overlap with the requirements for most commercial mushrooms.

Poor ventilation leads to stagnant air, allowing spores to accumulate and settle on fresh substrates or maturing fruiting bodies.

Inadequate sterilization of the substrate before spawning provides the pathogen with a substrate free from competition, allowing it to dominate.

Cross-contamination via tools, water droplets, and human handling is a common factor in transferring the infection between different grow rooms.

The economic impact of Lecanicillium psalliotae is significant, often resulting in severe yield losses if management practices are neglected.

Direct competition with the cultivated mushroom mycelium leads to a reduction in the biological efficiency of the crop.

The quality of the harvest is completely compromised as the pathogen renders the mushrooms unappealing and potentially unhygienic due to tissue degradation.

Once established, the pathogen can become endemic to a facility, requiring costly and time-consuming efforts to restore hygiene standards.

The necessity to dispose of contaminated substrate adds further costs to production, affecting the overall financial performance of the mushroom farm.

Implementing strict hygiene protocols is the most effective way to prevent the establishment of the pathogen in production environments.

Ensure that all substrate undergoes thorough pasteurization to eliminate dormant spores before being introduced into the growth chambers.

Regular monitoring allows for the early detection of infection; removing localized outbreaks immediately can prevent wider contamination.

Maintaining optimal airflow and avoiding excessive moisture on the surfaces of the mushrooms helps create conditions unfavorable for the fungus.

Disinfection of tools and footwear between rooms is essential to stop the mechanical spread of the spores throughout the facility.