Rice kernel smut

Taxonomic position and type of pathogen. Neovossia horrida (syn. Tilletia barclayana) belongs to the kingdom Fungi, phylum Basidiomycota, and class Ustilaginomycetes. It is a highly specialized fungal pathogen known as the causal agent of kernel smut in rice, a disease that presents a significant challenge to global rice production.

Diseases and susceptible crops. The pathogen primarily infects rice (Oryza sativa). The disease manifests when the developing grain is transformed into a mass of black teliospores. This infection ruins the quality of the rice, rendering it unsuitable for milling or consumption due to contamination and a distinct, unpleasant fishy odor caused by trimethylamine.

Biology and life cycle. The life cycle of Neovossia horrida involves the survival of teliospores in the soil or on crop debris. Under favorable environmental conditions, these spores germinate to produce basidiospores, which are then disseminated by wind or rain splash. The pathogen infects the rice plant during the flowering stage, penetrating through the floral parts to colonize the developing ovaries.

Conditions for development and economic impact. The development of kernel smut is favored by high humidity (often exceeding 85%) and moderate temperatures during the anthesis period. The economic damage is significant, as the pathogen reduces both grain yield and quality. Furthermore, because it is a regulated quarantine pest, its presence can lead to severe restrictions on grain trade and export.

Protection and control measures. Management of rice kernel smut requires an integrated strategy to minimize pathogen transmission:

• Using high-quality, certified pathogen-free seeds.
• Implementing crop rotation practices to reduce spore load in the soil.
• Cultivating resistant rice cultivars suited to local conditions.
• Deep plowing to bury crop residues that harbor overwintering teliospores.
• Applying systemic fungicides at the early flowering stage if conditions are favorable for disease outbreak.