BACTERIAL BLIGHT

DISEASE OF FIELD CROPS

1. BACTERIAL LEAF BLIGHT

2. BACTERIAL LEAF BLIGHT CASUAL ORGANISM : Xanthomonas oryzae pv . oryzae Telugu name : bacteria aaku endu tegulu First identified in japan 1884 [ I ndonesia ]

3. SYMPTOMS AND SIGNS Wilting of plants . Wilt syndrome known as Kresek is seen in seedlings within 3-4 weeks after transplanting of the crop. The bacterium enters through the hydathodes and cut wounds in leaf tips, and cause death of entire seedling. The lesions enlarge both in width and length with a wavy margin and turn straw yellow within few days. Milky dew drops containing bacterial masses are formed on young lesions in the morning.

4. DISEASE CYCLE INOCULUM : Inoculum present in rice stubble and weed hosts. The pathogen may be present for a short time on infected seed and soil. TRANSMISSION : The bacterium spreads by irrigation water, rain, plant to plant contact, and tools for transplanting seedlings. INFECTION : The bacterium enters leaf tissues through natural openings such as hydathodes and stomata on leaf blades , wounds on leaves and roots. Some bacteria invade the vascular system and may ooze from hydathodes . PRIMARY INFECTION : through seeds.

5. FAVOURABLE CONDITIONS Clipping of tip of the seedling at the time of transplanting. Heavy rain. Heavy dew. Flooding. Deep irrigation water. Severe wind. Temperature of 25-30 degrees. Application of nitrogen.

6. MANAGEMENT Grow resistant cultivars like MTU 9992,Swarna,Ajaya,etc. Affected stubbles are to be destroyed by burning or through ploughing . Judicious use of nitrogenous fertilizer. Avoid clipping of tip of the seedlings at the time of transplanting. Avoid flow of irrigation water from infected to healthy field. Spray psuedomonas florescens at 1kg per acre with 200lt of water. Application of bleaching powder@ 2kg/acre in the irrigation water at kresek stage {>60 DAT }. Soak seeds with A gromycin followed by hot water treatment and spray streptomycin 250ppm