Agriculture Department asks farmers to guard their crop against bacterial leaf blight disease

Symptoms found in Tiruverumbur and Lalgudi blocks

With incidence of bacterial leaf blight disease being noticed in standing samba and thaladi paddy crop in a few parts of the district, the Agriculture Department has advised farmers to take appropriate measures to check its spread.

Symptoms of the disease could be seen in a few fields in Tiruverumbur and Lalgudi blocks in the district, officials said. Samba and thaladi paddy crop have been raised on about 56,000 hectares in the district this year. The disease could affect yield as it did in the district a few years ago, the department has cautioned farmers.

“Due to the intermittent rain during the north-east monsoon and favourable climatic conditions, symptoms of bacterial leaf blight are appearing in the crop. The bacterium enters through the cut wounds in the leaf tips and edges, becomes systemic and causes orange and yellow coloured wavy margins in the leaf tips and edges,” M. Murugesan, Joint Director of Agriculture, Tiruchi, told The Hindu.

Clipping of the tip of the seedling at the time of transplanting, heavy rain or dew, flooding, deep irrigation water, severe wind and application of excessive nitrogen, especially by way of late top dressing, are some of the favourable conditions for the spread of the disease.

The disease symptoms first appear as small water-soaked translucent lesions on the edges of the leaf blade which later turn yellowish orange or brown. As the disease progresses, the yellowish orange or brown lesions cover the entire leaf blade which may turn straw coloured. This would affect photosynthesis leading to a reduction in the yield, said R.Sugumar, Assistant Director of Agriculture, Lalgudi.

Farmers can diagnose the disease easily, by cutting the leaf blade of the plant and dipping it in water. If affected, the water would turn turbid due to white bacterial ooze. The bacterial infestation would lead to secondary infestation, causing fungal diseases in the later stage of the crop.

If the disease is in the initial stage, farmers can spray 20% cow dung extract on the crop, twice at 15 days interval. To control developed symptoms, 120 grams of streptomycin sulphate and tetracycline hydrochloride combination along with 500 grams of copper oxychloride mixed in 200 litres of water should be sprayed per acre. The spraying should be repeated after 15 days.