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 [Indonesia]

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 Agromycin followed by hot water treatment and
spray streptomycin 250ppm