Pellicularia filamentosa

Pellicularia filamentosa is a pathogenic soil-borne fungus belonging to the Basidiomycota division. In its asexual stage, it is widely recognized as Rhizoctonia solani. This fungus is a devastating polyphagous pathogen, known for its ability to infect a vast range of monocot and dicot plants across various agro-ecological zones globally.

The fungus is responsible for several destructive plant diseases, primarily characterized as damping-off, root rot, stem canker, and fruit blight. Among the most affected crops are potatoes, rice, cotton, legumes, and various vegetable species. The pathogen attacks the plant tissue by producing necrotrophic enzymes that cause rapid cellular collapse and necrosis of the stems and roots.

The biology of the pathogen centers on its survival in soil as mycelium or sclerotia, which are dark, durable resting structures. These sclerotia can remain viable in the soil for several years, making the pathogen difficult to eradicate. It infects plants through the epidermis of roots or hypocotyls, spreading rapidly through the soil matrix as environmental conditions become favorable.

Environmental conditions play a critical role in disease severity, with moderate temperatures (15–25 °C) and high soil moisture being the primary triggers for outbreaks. Excessive nitrogen fertilization, poorly drained soils, and acidic conditions often exacerbate the intensity of the infection, providing the fungus with competitive advantages over beneficial soil microorganisms.

Effective control measures require a multi-faceted approach to reduce the inoculum level in the field:

• Implementing strict crop rotation sequences using non-host crops to starve the fungus.
• Treating seeds, tubers, and transplants with effective chemical or biological fungicides.
• Ensuring optimal drainage and field preparation to prevent waterlogging.
• Deep tillage practices to bury and accelerate the decomposition of infected crop debris.
• Monitoring soil health and maintaining balanced nutrient levels to promote vigorous plant growth.