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Agricultural crops :: Cereals :: Rice

Sheath Rot

Causal organism: Sarocladium oryzae (Syn : Acrocylindrium oryzae)

Symptoms:

  • Initial symptoms are noticed only on the upper most leaf sheath enclosing young panicles.
  • The flag leaf sheath show oblong or irregular greyish brown spots.
  • They enlarge and develop grey centre and brown margins covering major portions of the leaf sheath.
  • The young panicles may remain within the sheath or emerge partially. The panicles rot and abundant whitish powdery fungal growth is formed inside the leaf sheath
Brown discolouration of boot leaf sheath
Pathogen:
  • The fungus produces whitish, sparsely branched, septate mycelium.
  • Conidia are hyaline, smooth, single celled and cylindrical in shape.
Favourable Conditions :
  • Closer planting, high doses of nitrogen, high humidity and temperature around 25-30 C.
  • Injuries made by leaf folder, brown plant hopper and mites increase infection.
Mode of Spread and Survival :
  • Mainly through air-borne conidia and also seed-borne.

Management:

  • Spray Carbendazim 100g or Edifenphos 200ml or mancozeb 500 g /ac at boot leaf stage and 15 days later.
  • Soil application of gypsum (200 kg/ac) in two splits.
  • Application of NSKE 5% or neem oil 3 % or Ipomoea or prosopis leaf powder extract 10 Kg/ac.
    First spray at boot leaf stage and second 15 days later.

Source of information:

  • AICRIP rice, TNAU, Coimbatore Rice diseases- online resource, IRRI, Phillippines.

Acknowledgements:

  • IRRI, Phillippines


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