Rhizoctonia zeae

Rhizoctonia zeae is a soil-borne fungal pathogen belonging to the kingdom Fungi, phylum Basidiomycota, and the genus Rhizoctonia. It is a well-known agent of root and stem rot diseases affecting various crops, particularly maize (corn), sorghum, and rice, causing significant physiological stress and agricultural yield losses globally.

This pathogen causes several types of infections, primarily characterized by root rot, seedling blight, and lower stem decay. It functions as a facultative parasite, meaning it can survive as a saprophyte on decaying organic matter in the soil when host plants are not present, allowing it to remain viable in agricultural fields for extended periods.

The biological cycle of Rhizoctonia zeae revolves around the formation of sclerotia, which are compact masses of hyphae that act as dormant survival structures. These sclerotia germinate in the soil in response to chemical signals from growing plant roots. Once the fungus contacts the host, it colonizes the tissue, causing tissue breakdown and necrosis that disrupts the plant's nutrient and water uptake systems.

Favorable conditions for the development of Rhizoctonia zeae include warm, moist soil environments, with temperatures between 25°C and 30°C being optimal for mycelial growth and infection. It spreads through soil movement, contaminated machinery, irrigation water, and infected crop residues, making it a difficult pathogen to eradicate once it becomes established in a field.

The pathogenicity of this fungus leads to stunted plant growth, chlorosis, and severe lodging. Because the root system is often destroyed, affected plants are highly susceptible to drought and nutrient deficiencies. Economically, this results in significant grain yield reduction and poor kernel quality, which poses a substantial challenge for farmers managing large-scale monoculture systems.

• Implement strict crop rotation patterns to break the pathogen's life cycle.
• Treat seeds with systemic fungicides effective against Basidiomycetes.
• Ensure proper soil drainage to avoid waterlogged conditions.
• Remove or incorporate crop residues deeply to reduce the inoculum load.
• Monitor soil health and maintain balanced fertilization to promote vigorous root growth.