Disease:Bacterial Leaf Blight

The disease is prevalent in two major rice growing regions of Kerala viz. Palghat and Kuttanad. In Kuttanad, it is noticed in both punja (Nov-Dec to Feb-Mar) and additional crop (June-Jul to Sep-Oct), the severity being more in the additional crop.

  • Disease 1
  • Disease 2
  • Disease 3
  • Disease 4
  • Disease 5
  • Disease 7
  • Disease 8


  • The disease is noticed both in the seedling and in mature plant stage .One to two weeks after transplanting, the seedlings show systemic infection known as Kresek.
  • Infected leaves and sheath starting from the older ones at the periphery become water soaked and grayish green and fold up and roll along the midrib. These leaves wither and float in water.Thereafter, the bacterium is carried through xylem vessels and becomes systemic and the entire plant wilts. This symptom is often confused with damage caused by stem borer injury (dead heart) but the latter can be easily pulled out while it is not so with kresk affected tillers.
  • On the mature leaf blades, lesions appear as yellow to white water soaked stripes at the margins which enlarge in length and width and produce the characteristic yellow lesions with wavy margin.
  • The regions adjacent to the lesion show water soaking. Later, as a result of growth of saprophytic fungi the dead portion of the lesion turns dark or grayish. On susceptible varieties, the sheaths are also affected.
  • On resistant varieties, yellow stripes may be formed which after several days turns brown and necrotic.
  • Milky or opaque dewdrops may be noticed on the surface of young lesion in the early morning. These dry up to form small, yellowish, spherical beads, which get detached easily and fall down into the field.The grains may also show infection, which become discoloured and get surrounded by water soaked margin.

Procedure for Observation

Ooze test is a simple method to identify the disease. Mark 4 one square meter plots randomly in the field. From each square meter select five hills at random. Conduct ooze test to confirm the incidence and workout the % of plants affected.

2- 5 % Light to moderate


  • ET L: 2%.
  • Control Measures

  • Use of disease free seeds.
  • Eradication of bacterium by soaking the seeds in Agrimycin 100-250 ppm (2.5g/10kg seed) for 12 h. followed by hot water treatment at 52oC for 30 min. In BLB prone areas treat the seeds with bleaching powder (100g/L)and Zinc sulphate (2%).
  • Destruction of collateral weed hosts.
  • Apply of bleaching powder at the rate of 5kg/ha in the irrigation water to check the spread of BLB especially in the kresek stage.
  • Spraying fresh cow dung extract (20g cow dung is mixed in 1L water and allowed to settle and sieved). The supernatant is taken for spraying @500l/Ha. Spraying antibiotics like Streptocycline 15g/300l/ha. Agrimycin 100 750g/500l/Ha.