Paddy Bacterial Leaf Blight - High Yields Agro

Symptoms

Bacterial blight syndrome exhibits three types of symptoms: leaf blight, kresek (the seedling blight or wilt phase) and the pale-yellow leaf.
The disease has been referred to as “bacterial leaf blight” to indicate that the “leaf blight” phase of the syndrome is the most distinct and commonly observed symptom.
Seedlings in the nursery show circular, yellow spots in the margin, that enlarge, coalesce leading to drying of foliage.
“Kresek” symptom is seen in seedlings, 1-2 weeks after transplanting.
The bacteria enter through the cut wounds in the leaf tips, become systemic and cause death of entire seedling.
In grown up plants water soaked, translucent lesions appear near the leaf margin.
The lesions enlarge both in length and width with a wavy margin and turn straw yellow within a few days, covering the entire leaf.
As the disease advances, the lesions cover the entire lamina which turns white or straw coloured.
Milky or opaque dew drops containing bacterial masses are formed on young lesions in the early morning.
They dry up on the surface leaving a white encrustation.
The affected grains have discoloured spots.
If the cut end of leaf is dipped in water, it becomes turbid because of bacterial ooze.

Management

Favourable conditions / Epidemiology:
- Clipping of tip of the seedling at the time of transplanting
- Heavy rain, heavy dew, flooding, deep irrigation water
- Severe wind and temperature of 25-30 ⁰C
- Application of excessive nitrogen, especially late top dressing
Antagonistic Bacteria: Use biological control agents like Pseudomonas fluorescens and other antagonistic bacteria that can suppress Xanthomonas oryzae populations in the field