Rice Sheath Blight

  • Symptoms

  • Trigger

  • Biological Control

  • Chemical Control

  • Preventive Measures

Rice Sheath Blight

Rhizoctonia solani

Fungus


In a Nutshell

  • Oval, green to grey water-soaked lesions on stalks (sheaths) near the water line.
  • Irregular grey to white lesions with brown margins appear on leaves and stalks.

Hosts

Rice

Symptoms

Initial symptoms of the disease are lesions on stalks (sheaths) near the water line. 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.

Trigger

Optimal conditions for rice sheath blight are high temperatures between 28 and 32°C, high levels of nitrogen fertilizer and a high relative humidity of 85-100%. Especially during rainy season, the risk of infection and spreading of the disease is high. Close canopy is favoring 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.

Biological Control

Sorry, we don't know of any alternative treatment against Rhizoctonia solani . Please get in touch with us in case you know of something that might help to fight this disease. Looking forward hearing from you.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. To prevent an infection, use fungicides of the family of the strobilurins or a combination of strobilurin + propiconazole to control the disease. Other possible treatments include propiconazole and trifloxystrobin + tebuconazole, alternating the sprays twice at 15 days interval.

Preventive Measures

Use a recommended dose of fertilizer adapted to the cropping season.,Maintain optimum density of crop establishment (direct seeding or transplanting).,Control host weeds, especially on the bunds.,Ensure good drainage of the field early in the season to avoid epidemic proportions.,Keep sufficient space between plants.,Avoid early planting as this favor the disease.