Rhizoctonia fusispora blight

Causal agent and disease type: Rhizoctonia fusispora is a soil-borne fungal pathogen responsible for root and stem rot in various plant species. It is a member of the Rhizoctonia genus, characterized by the absence of asexual spores and the production of resilient mycelium and sclerotia. The disease is primarily a soil-borne vascular and root infection that significantly hampers plant nutrient uptake.

Susceptible crops: This pathogen affects a wide range of host plants, including various horticultural crops, cereals, and ornamental species. It is particularly destructive during the germination and seedling stages, causing pre-emergence and post-emergence damping-off. Its ability to survive on crop debris makes it a persistent challenge in diverse agricultural environments.

Symptoms and signs: Typical symptoms include necrotic lesions on roots and the hypocotyl area, often turning dark brown or black. Affected seedlings may exhibit constriction at the stem base, leading to collapse and lodging. In advanced stages, the roots appear decayed, and the plant stops growing. Under high humidity, a sparse, cobweb-like mycelium may be visible at the base of the stem.

Development and spread conditions: The development of Rhizoctonia fusispora is highly favored by cool, moist soil conditions. The pathogen thrives in temperatures between 15°C and 22°C, which often coincide with early planting seasons. Poorly drained soils, high plant density, and high organic matter content that remains waterlogged create a perfect environment for the fungus to multiply and spread.

Protection and prevention measures: Effective management relies on an integrated approach to reduce the inoculum levels in the soil. Recommended practices include:

• Implementing strict crop rotation schedules to starve the pathogen of its host.
• Sanitation protocols, such as removing and destroying all infected plant residues.
• Using high-quality, fungicide-treated seeds to protect young seedlings.
• Improving soil drainage and physical structure to prevent excessive moisture build-up.
• Applying balanced fertilization to improve plant vigor and natural resistance against soil-borne infections.