Rice Bacterial Blight Management

                                            S. Parthasarathy, Ph.D Scholar, Dept. of Plant Pathology, TNAU, Coimbatore

Bacterial Leaf Blight:

            Causal Organism : Xanthomonas oryzae pv. oryzae

Symptoms:

            Seedling in the nursery show circular, yellow spots in margin, later enlarge, coalesce and cause drying of foliage. ‘Kresek’ symptom is seen in seedlings.  The lesions cores the entire leaf blade which may turn white or straw coloured.  The affected grains have discoloured spots surrounded by water soaked areas.

Pathogen:

            The bacterium is strict aerobe, gram negative, rod shopped Non Spore forming.  The bacterial cells are capsulated and are joined to form an aggregate mass.  Colonies are circular, convex with entire margins.

Mode of spread and Survival:

            The pathogen survives in soil & on collateral hosts like Cyanodon dactylon, Leersia spp.  The pathogen spreads through irrigation water in dry season and also through typhoons and rain stroms.

Management:

            Avoid clipping of tip of seedling at the time of transplanting.  Remove weed hosts grow resistant cultivars like IR20 and TKM6.  Spray streptomycin sulphate and Tetracycline combination 300 g + Copper Oxychloride 1.25 g/ha.