Paecilomyces variotii

Systematic position and nature of the pathogen: Paecilomyces variotii belongs to the kingdom Fungi and the genus Paecilomyces. It is an anamorphic ascomycete recognized for its high thermotolerance. While it frequently functions as a saprotroph in nature, it acts as a facultative plant pathogen capable of infecting various agricultural crops and stored commodities.

Diseases and host crops: This pathogen is responsible for various forms of rot, particularly in stored agricultural produce. It affects cereal grains, oilseeds such as soybeans and sunflowers, and many vegetable crops. Infection typically results in reduced seed germination rates, loss of vigor, and deterioration of the internal quality of the harvested produce.

Biology and life cycle: The life cycle of Paecilomyces variotii is characterized by the prolific production of conidia, which are easily disseminated by air currents. Due to its thermotolerant nature, the fungus thrives at temperatures that often suppress other competing microflora, allowing it to colonize materials rapidly in warm environments or heating storage piles.

Conditions for development and harmfulness: The fungus prefers high humidity and temperatures ranging from 25°C to 45°C. Its harmfulness is significant due to its ability to spoil crops, produce mycotoxins that threaten food safety, and reduce the economic value of stored grains by compromising their nutritional and physical integrity.

Protection and control measures: Management of Paecilomyces variotii requires strict adherence to post-harvest and field management protocols:

• Maintaining proper moisture levels (below 14% for grain) to inhibit fungal growth.
• Implementing effective aeration and cooling systems in storage facilities.
• Sanitizing agricultural equipment and storage bins to reduce inoculum levels.
• Using certified seeds treated with appropriate fungicides.