Disease symptoms and visual identification
- Kresek phase (seedling stage): Translocated infection causes seedlings to wilt, roll up, turn dull greyish-green, and wither completely within 1 to 3 weeks of transplanting.
- Leaf blight phase (vegetative to reproductive stage): Water-soaked lesions appear on leaf tips and margins, expanding into yellowish-white wavy stripes along leaf veins.
- Bacterial ooze test: Freshly infected leaf sections suspended in clean water release milky cloudy bacterial ooze from cut vascular bundles within minutes.
- Severely diseased leaves turn straw-yellow, dry up prematurely, and cause poorly filled, discoloured panicles.
Epidemiology and disease transmission factors
- Favourable conditions: Temperatures of 25 to 34 degrees Celsius paired with high relative humidity exceeding 80 percent, heavy rainstorms, and strong winds.
- Transmission: Bacterium enters plant tissues through natural hydathodes or mechanical wind-inflicted leaf tears and moves systemically through xylem vessels.
- Aggravating factors: Excessive application of nitrogenous fertilizers creates soft, succulent foliage highly susceptible to rapid bacterial multiplication.
Integrated management and spray protocols
Cultivate resistant or tolerant paddy varieties recommended by local agricultural universities. Avoid excessive urea application; instead, apply nitrogen in split doses combined with recommended potash. Spray copper hydroxide or validamycin formulations mixed with bactericides at early symptom onset, ensuring field water depth is regulated to prevent bacterial spread across bunds.
Official source
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ICAR - National Rice Research Institute (NRRI) ↗Related on KisanPe
Common questions
What causes bacterial leaf blight in rice?
Bacterial leaf blight is caused by the vascular plant pathogen Xanthomonas oryzae pv. oryzae.
What is the difference between kresek and leaf blight symptoms?
Kresek is the acute seedling wilt phase occurring 1 to 3 weeks after transplanting, while leaf blight is the chronic foliar striped lesion phase occurring during tillering and heading.
How does nitrogen fertilizer management help control BLB?
Excessive nitrogen produces lush, succulent leaves that facilitate bacterial infection; applying balanced, split nitrogen doses with adequate potassium reinforces leaf cell walls.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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