Short notes on Bacterial blight of rice (Xanthomonas oryzae)

This disease is caused due to Xanthomonas oryzae syn Pseudomonas oryzae, syn Bacterium oryzae, syn Phytomonas oryzae.

This disease was first reported in Japan in 1908 and was thought to be confined to that country. However, the incidence of disease has been reported in India in recent years.

Symptoms

The bacterial leaf blight or bacterial blight is a typical vascular disease, the effect of which is expressed on the foliage. It appears early or late in August when the stems and leaves, begin to extend and it causes maximum damage during the heading season.

Water soaked translucent spots appear on the margins of the leaves and along the mid ribs and sometimes on leaf sheaths. They gradually increase to elongated streaks. Soon the streaks turn yellow to white in color. The margins of all these, leaves appear dry.

Under humid conditions, there is generally bacterial exudate in the form of clouded droplets in the affected portions. The bacterial exudates dry and harden into yellowish resinous granules.

Internally, the vascular bundles become filled with bacteria. The plant growth ceases, all vital functions get affected, leaves roll up and droop, become yellow to brown and finally the plant dies.