Initial symptoms of the disease are lesions on stalks (sheaths) near the waterline. These lesions are oval, greenish-grey, 1-3 cm long and water-soaked. These lesions grow irregularly and turn grey to white with brown margins. As the disease progresses, the upper parts of the plant are infected. On these parts, rapidly growing lesions appear and the whole leaf brightens. This can result in the death of the leaf and the whole plant. Furthermore, fungal pustules form on the plant surface.
Optimal conditions for rice sheath blight are high temperatures between 28 and 32°C, high levels of nitrogen fertilizer and high relative humidity of 85-100%. Especially during the rainy season, the risk of infection and spreading of the disease is high. Close canopy favors humid conditions and contact. The fungus survives in the soil for several years as a dormant sclerotium. It floats to the surface when sites are flooded. Once in contact with a rice plant, the fungus enters the leaf sheath, starting the infection process.
Unfortunately, no effective biological control methods are available at this time.
Always consider an integrated approach with preventive measures together with biological treatments if available. To prevent infection, use the following fungicides: hexaconazole 5EC (2 ml/l) or validamycin 3L (2ml/l) or propiconazole 25 EC (1ml/l) or trifloxystrobin + tebuconazole (0.4g/l). Alternate the sprays twice at 15 days interval.