Bacterial leaf streak
(Xanthomonas oryzae pv. Oryzicola)

• Initially, small, dark-green and water-soaked streaks on interveins from tillering to booting stage
• The progress of the streaks is longitudinal, limited by the veins and soon turn yellow or orange brown.
• All along the streaks bacterial exudates could be observed as tiny yellow or amber colored droplets.
• These streaks may coalesce to form large patches and cover the entire leaf surface.
• Lesions turn brown to greyish white then dry when disease is severe
• Infection in the florets and seeds results in brown or black discoloration and death of ovary, stamens and endosperm and browning of glumes.

• The bacteria causing the disease X. oryzae pv.oryzicola occur as rods.
• The bacteria have no spores and no capsules.
• They move with the aid of a single polar flagellum.
• They are Gram-negative and aerobic and can grow favorably at 28 °C.
• The bacterial colonies on nutrient agar are pale yellow, circular, smooth, convex, and viscid and have an entire margin.

Factors favoring disease development

• Presence of the bacteria on leaves and in the water or those surviving in the debris left after harvest
• Warm temperature and high humidity
• Early stage of planting from maximum tillering to panicle initiation

• The disease can be controlled by proper application of fertilizers and proper plant spacing, use of resistant varieties, and hot water treated seeds.
• Practicing field sanitation is important.
• Ratoons, straws and volunteer seedlings left after harvest can be destroyed to minimize the initial inoculum at the beginning of the season.
• Providing good drainage system especially in seedbeds can also manage this disease.
• Planting of resistant varieties (IR 20, TKM 6) is the most effective method of controlling bacterial leaf streak.
• Grow nurseries preferably in isolated upland conditions
• Avoid clipping of seedlings during transplanting.
• Spray fresh cowdung water extract or lemon grass or mint extract at 20 %.
• Spraying streptomycin sulphate and tetracycline combination 300g +copper oxychloride 1.25 kg/ha.