Disease:Sheath Rot

Sarocladium oryzae (syn. Acrocylindrium oryzae) - Anamorph

Sheath rot was considered a minor disease but became increasingly destructive and widely distributed. The disease causes 3-20% damage and up to 85% in severe disease conditions.

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  • Disease 1
  • Disease 2
  • Disease 3
  • Disease 4
  • Disease 5
  • Disease 6
  • Disease 7
  • Disease 8
  • Disease 9
  • Disease 10
  • Disease 11
  • Disease 12

Symptoms

  • Sheath rot affects the upper leaf sheaths, which encloses young panicles.
  • The lesions are oblong to irregular in shape, and are 0.5-1.5cm long. The lesions may have brown margins and grey centre or uniformly grayish brown.
  • Gradually lesions enlarge and cover entire sheath.Whitish mycelium can be seen in the centre of the lesions on the inner side of the affected sheath.The developing panicles are choked within the rotten sheath.
  • Sometimes partial emergence is also noticed. The resulting grains will be chaffy or poorly filled, shriveled and discoloured.

Procedure for Observation

Mark 4 one square meter plots in the field at random. Select 5 hills at random from each plot. From this calculate the total number of tillers and the tillers showing the symptoms of sheath rot. Estimate the % infection.

ETL

  • At panicle initiation to booting and flowering and after: 5 % or more tillers affected.

    • Control Measures

  • Use of healthy seeds collected from disease free plants.
  • Seed treatment by dipping seeds in hot water at 500C for 5-10 min.
  • Seed treatment with carbendazim 2g/kg seed.
  • Destroy crop residues immediately after harvest to reduce inoculam level.
  • Manage pests such as stem borer and nematodes.
  • Balanced application of NPK fertilizers.
  • Apply neem cake coated urea.
  • Apply 50% more potash than recommended dosage in split application. Apply potash at tillering stage..
  • Ensure good weed control.
  • Use of resistant varieties such as Aruna, Athira, Asha, Resmi, Nila, Remya, Rajani, and Arathy.
  • Spray fungicides such as Carbendazim 500g /Ha or carboxin 500 g/Ha at booting stage.