Shahbazi , H. (2024). Epidemiology and management methods of rice sheath blight disease. Plant Pathology Science, 13(1),42-54.
Sheath blight (ShB) caused by the soil-borne fungus Rhizoctonia solani AG1-IA is one of the most important diseases of rice in the world, which is also common in some areas of rice cultivation in Iran. The pathogen usually overwinters as sclerotia in soil and plant debries and mycelium in plant debris and seeds. Sclerotia can survive inactive in soil, and rice debris for several years. After transplanting susceptible rice cultivars, the sclerotia germinate, produce mycelium, and infect the lower sheaths of the rice plant. The characteristic symptoms of ShB are green-gray water-soaked lesions, spherical to oval, or irregularly discolored on rice sheath. The lesions are connected, and the center of the lesions becomes gray to light brown with a dark brown-to-red border, by passing time. Factors such as the rice variety, plant density, and growth stage, initial inoculum population of the pathogen, environmental conditions, and plant nutrition affect the disease severity and epidemic. The disease management is difficult, because of the wide host range of the pathogen, its ability to survive for a long time in the soil, and the low level of resistance of rice cultivars to it. Proper management such as avoiding cultivation of dwarf and high tillering cultivars in fields with a history of pathogen presence, seed disinfection, proper plant densities, and optimal use of nitrogen fertilizer, field sanitation, and chemical control can prevent the epidemy and damage of the disease.
