Bacterial blight is a damaging pest that affects rice crops. It has yellowish stripes on the leaves, a wavy edge, and a milky dewdrop visible on the leaf surface in the early morning. Lesions develop yellow to white as the illness spreads, and highly diseased leaves dry fast. Bacterial leaf blight of paddy is caused by Xanthomonas oryzae pv. oryzae happens when the crop is in the stage between tillering and heading.
The native name for this disease is “Dundanu Macchhe Roga.” Yield loss can range from 6-60% in severe circumstances, and alternative hosts include grasses such as Leersia spp. and Cyperus rotundus.
Bacterial Leaf Blight management in Paddy
The causal organism of Bacterial Leaf Blight disease
Xanthomonas oryzae is the bacterium that causes bacterial blight in rice crops. It is a non-capsulated, gram-negative, rod-shaped bacteria that are aerobic, does not form spores, and measures 0.5–0.8 x 1-2 micrometres. It moves with a single polar flagellum, forming waxy yellow colonies on agar media. The optimal development temperature is 28–30°C, while the thermal death point is 53°C.
The Disease cycle of Bacterial Leaf Blight disease
- Bacterial leaf blight can be transmitted by seed and live for lengthy periods in seed or plant residue.
- Seed, rain and sprinkler watering, and damp weather are all conditions that help spread the disease.
- Bacteria emerge in the mid to high canopy and can spread throughout the plant, harming leaves, pods, and fruits.
- The disease appears early in the growing season while seedlings are forming.
- Once infected, the bacterium affects all phases of plant development and can cause premature defoliation.
- Defoliation exposes the plant’s fruit to direct sunlight, potentially resulting in significant production loss.
Mode of spread and survival of the pathogen in Paddy crop
The pathogen survives in soil and infected stubbles and on collateral hosts Leersia spp., Plantago najor, Paspalum dictum, and Cyanodon dactylon. The pathogen spreads via irrigation water as well as rainstorms.
Causes of Bacterial Leaf Blight Disease spread in the field
- Combinations of Humid weather above 70%, dull windy days.
- Very late top dressing and Flooding.
- Excessive rain and deep irrigation water
- Air temperature ranges from 22 to 26 degrees Celsius.
- N in high concentrations in the field.
- Planting nearby
Symptoms of Bacterial Leaf Blight disease
- Bacterial Blight Disease expresses itself in three ways: leaf blight, kresek, and pale-yellow leaf.
- The most noticeable and prevalent symptom is leaf blight. Circular yellow dots form on the leaves of seedlings and can cause the seedling to die.
- Water-soaked transparent lesions occur along the leaf margin in mature plants, expand, and become straw yellow. Lesions can cover the entire leaf, resulting in a white or straw-colored appearan