Bacterial leaf blight (rice)
Rice leaves drying from the tips and margins in wavy, water-soaked yellow streaks — and, in seedlings, whole-plant wilt ("kresek").
- Pathogen
- Bacterium (Xanthomonas)
- Spreads by
- Water, wind-damaged leaves, seed
- Favoured by
- Warm, humid, rainy, windy weather
- Main risk
- Leaf drying; seedling wilt (kresek)
Overview
Bacterial leaf blight (Xanthomonas oryzae) is one of the most serious bacterial diseases of rice. It typically starts as water-soaked streaks at the leaf tips and along the margins, which turn yellow then straw-white and dry, spreading inward and downward in a characteristic wavy (undulating) margin. Heavily affected fields take on a scorched, dried look.
In young plants, an aggressive early infection can wilt and kill whole seedlings or tillers — a phase called "kresek" that looks like the plants have suddenly dried up. In the morning, dew may show tiny yellowish bacterial droplets (ooze) on fresh lesions. The bacterium spreads in warm, humid, rainy weather and through wind- and water-damaged leaves, enters through wounds and leaf pores, and is carried in irrigation water, on infected debris and in seed — so management centres on resistant varieties, balanced nutrition, water management and clean seed rather than sprays.
How to identify it
- Water-soaked streaks at the leaf tips and margins that turn yellow, then straw-white, and dry — spreading inward with a wavy (undulating) edge.
- Fields taking on a scorched, dried, straw-coloured look under heavy infection.
- In seedlings/young tillers, sudden wilting and drying of whole plants — the "kresek" phase.
- Tiny yellowish bacterial ooze droplets on fresh lesions in the early-morning dew (a bacterial, not fungal, sign).
What causes it and when
- The bacterium Xanthomonas oryzae, entering through wounds and leaf pores and blocking the water channels.
- Favoured by warm, humid, rainy and windy weather — wind and storms wound the leaves and let the bacteria in, and flooding spreads them.
- Spread in irrigation and flood water, by leaf-to-leaf contact, and carried in infected seed and crop debris/ratoons/weeds.
- Worsened by excess nitrogen and dense, lush crops, and by deep, stagnant flooding.
Cultural & organic control
- Grow resistant varieties — the single most effective control — and use clean, healthy seed (a hot-water/recommended seed treatment helps).
- Avoid excess nitrogen and split it into recommended doses; over-fertilised lush crops are hit far harder.
- Manage water — avoid deep, stagnant flooding, drain the field intermittently, and do not let run-off carry the disease from infected patches.
- Destroy infected stubble, ratoons and weed hosts, and avoid clipping/handling the crop when wet.
Chemical control
- There is no reliable chemical cure — bacterial leaf blight is managed with resistant varieties, nutrition and water, not sprays.
- Where recommended, a copper-based bactericide (and, per official advisory, specific bactericide/antibiotic combinations) can slow spread, but these are supplementary and not a substitute for resistant varieties.
- Do not rely on general fungicides — they do not control this bacterium.
- Confirm the resistant varieties and any recommended treatment for your area with your local KVK/rice research station.
Prevent it coming back
- Base management on resistant varieties, clean seed and balanced (not excess) nitrogen.
- Manage irrigation water to avoid deep stagnant flooding and cross-field spread, and destroy stubble, ratoons and weed hosts.
- Avoid working the crop when wet, and don’t create leaf wounds unnecessarily.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My rice leaves are drying from the tips and margins with wavy yellow streaks. What is it?
That drying from the leaf tips and margins inward, in wavy, water-soaked yellow-to-straw streaks, is bacterial leaf blight. In the morning dew you may see tiny yellowish bacterial ooze droplets on fresh lesions. It spreads in warm, humid, rainy, windy weather. Manage it with resistant varieties, balanced nitrogen and careful water management — there is no reliable chemical cure.
What is "kresek" in rice?
Kresek is the severe, early phase of bacterial leaf blight in which an aggressive infection wilts and kills whole young seedlings or tillers, so the plants suddenly dry up as if scorched. It is most damaging on young crops in warm, humid weather. Resistant varieties, clean seed, balanced nitrogen and good water management are the way to prevent it.
Why won’t fungicides control bacterial leaf blight?
Because it is caused by a bacterium (Xanthomonas), not a fungus, so ordinary fungicides do not control it, and there is no reliable chemical cure. It is managed with resistant varieties (the main tool), balanced nitrogen, careful water management, clean seed, and destroying infected debris. Copper-based bactericides may slow spread where recommended, but they supplement, not replace, resistant varieties.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.