Bacterial Leaf Blight and Its Control

The BLB is caused by the bacteria (Xanthomonas oryzae pv. Oryzae).

• The infestation can start at seedling stage and occurs more often at tillering stage.

• Dried leaves, withered and dead seedlings can be seen in the nursery.

Symptoms

• The symptoms start at the leaf tips and leave margins. It appears water-soaked to yellowish stripes and progress toward the leaf base. In one-two days, become grayish green to yellow or straw color stripes.

• Greenish-blue color or orange lesions with wavy margins can be seen where the infected leaf tissues and non-infected tissue are met. 

Source: Research Gate

 

Disease Cycle

• It survives in straw, plant residues of infested rice field, wild rice plants, weeds and infected seeds, then remitted to next season.

• Irrigation and drainage practices and the strong winds encourage pathogen bacteria spread across areas and infected into other rice fields through the injuries on plant parts.

 

Resistant Varieties

• The PSB Rc82 variety is resistant to BLB in South East Asia.

• Macassane variety in Mozambique Country, IR22 in Tanzania Country and IR 55 are moderate resistant varieties to BLB.

Good practices for prevention

• Clean the hosts in the field by ploughing the weeds, other host plants, straws and buried these under the soil.

• Fallow the plot between two rice seasons, to reduce pathogens staying in plant residues and in the soil. 

Chemical Control

 

• Seed treatment- seed treatment with recommended fungicides such as Copper oxychloride (or) Copper sulphate 

• Soak the seeds in Ceresan (0.1%) for 8 hours and then mix soaked seeds with Streptocyclin (3g/Lit of water)

• In the field - Spray Streptomycin sulphate+ Tetracycline 300g+ copper oxychloride 1.25kg/ha