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Brown leaf spot


Brown Spot: Helminthosporium oryzae (Breda de Haan) (Deuteromycotina: Moniliales : Dematiaceae )

Kannada Name: Kandu Chukke Roga

            Brown spot is a fungal disease that can infect both seedlings and mature plants. This disease is more severe in areas of poor management.

Period of occurrence: Seedling to maturity

Extent of yield loss: 50-90% in extreme cases

Collateral hosts: Digitaria sanguinalis, Leersia hexandra, Echinochloa colona, Pennisetum typhoides, Setaria italica, Cynodon dactylon.   

Favorable conditions for the pathogen

  • Temperature of 25-30°C
  • Relative humidity (>90%)
  • Heavy and late north-east monsoon
  • Cloudy days
  • High doses of N

Mode of transmission/ dissemination: wind

Sources of inoculum: Seed, Collateral hosts, Rice straw or Stubble


  • On seedlings - Small, slightly elongated or circular brown lesions are observed on coleoptiles and black discoloration of the roots cause distorted seedlings.
  • On leaves - Spots appear as circular to oval reddish brown lesions often surrounded by a yellow or gold halo.
  • On glumes - Black or brown spots appear and in severe cases the greater portion of the glume may be covered by these spots causing black discoloration.  This reduces the market value.

Brown Spot on leaves    Brown Spot on earhead   Brown Spot  affected on Grains

Preventive measures:

  • Use of resistant varieties - Rasi, IR 36, Jagannath.
  • Proper crop nutrition
  • Avoid water stress
  • Clean cultivation

Chemical control: Seed treatment with Mancozeb 75WP @ 2.5 g or Iprodione 50 WP @ 2 g per kg of seeds

Control measures:

Chemical control

Recommended fungicides

Sl. No.

Chemical name

Trade name

Dosage per l of water

Dosage for spray tank


10 l

12 l

16 l


Liquid/Spray formulations (EC, SL, WP, WG, WDG, SC)


Mancozeb 75 WP

Idofil M-45

2.5 g

25 g

30 g

50 g


Iprodione 50 WP


2.0 g

20 g

24 g

32 g


Carbendazim 50 WP

Bavistin, Jkstin Derosal

1.0 g

10 g

12 g

16 g


Chlorothalonil 75 WP


2.0 g

20 g

24 g

32 g


Edifunphos 50 EC


1.0 g

10 g

12 g

16 g


 Note : Spraying is to be avoided during the period of flowering.

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