Important Diseases of Rice – AgriBooks

Diseases of Rice

Disease of Rice/Paddy with their picture, causal organism, symptoms and management is mention below:

1. Blast or rotten neck of Rice/Paddy

Caused by Pyricularia oryzae.

  • Most severe Blast or rotten neck disease of rice, known as ‘rich man’s disease’ because high N, high relative humidity and night temperature of 20°C are congenial for fungus.
  • The fungus attacks the crop at all stages of crop growth (leaves, seed, panicle, nodes, etc.)
  • Affected plant shows diamond shaped lesions, eye-shaped spots with grey or dark brown margin from leaf and leaf sheath.
  • Air borne disease:- Conidia spread by wind cause secondary infection.
  • Favorable conditions:- Low night temperature (15-20 ℃) & high Relative humidity 93-99%.


  • Seed treatment with organomercurials like Agrosan GN @ 2.5 g/kg seed.
  • Use of resistance varieties of paddy like Jaya, IR 8, IR 24, IR 64 etc.Rotten Neck Blast
2. Brown leaf spot of Rice/Paddy

Caused by: Helminthosporium oryzae or Cochliobolus miyabeanus.

  • Responsible for Bengal famine of 1943.
  • Symptoms appear as minute spots on the coleoptile, leaf blade, leaf sheath, and glume, being most prominent on the leaf blade and glumes.

Favorable conditions

  • Temperature of 25-30with relative humidity above 80 per cent are highly favorable.
  • Severe on K deficient soils.


  • Treat the seeds with Thiram or Captan at 4 kg/kg.

Brown leaf spot of Rice

3. BLB (bacterial leaf blight) of Rice/Paddy

Caused by Xanthomonas oryzae.

  • bacterial leaf blight of rice is called Killer disease of rice.
  • ‘kresek‘ symptom is seen in seedlings, 1-2 weeks after transplanting.
  • Ooze test is used for this disease.


  • Balance dose of Nitrogen because high N can make the disease aggressive.
  • Use of tolerant varieties like IR 20, Pusa 2-21, TKM-6, Ajay etc.

bacterial leaf blight of rice

4. Sheath blight of Rice/Paddy

Due to Rhizoctonia solani.

  • Occurs in areas with high temperature (22-32°C) and relative humidity (85-100%)
5. Foot rot or bakanae disease or foolish seedling disease

Caused by Gibberella fujikuroi (prefect stage is Fusarium moniliforme)

  • Kurosova; a Japanese scientist isolated GA from Gibberella fujikuroi fungus and found the cause of this disease.
  • Due to this stunted growth and infertile seeds
Other Disease of Rice

S. No.




Blast of Rice

Pyricularia oryzae


Brown spot

Helminthosporium oryzae


Sheath blight

Rhizoctonia solani


False smut

Ustilaginoidea virens


Udbatta disease

Ephelis oryzae


Foot rot or Bakanae disease

Fusarium moniliforme


Bacterial leaf blight (Kresek)

Xanthomonas oryzae pv. Oryzae


Ufra disease

Nematode Ditylenchus angustus

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