Udbatta Disease of Rice
Symptoms first become evident at the time of panicle emergence.Infection is systemic and all tillers are involved. Infected plants are usually stunted and characterized by a white mycelial mat that ties panicle branches together. Panicles emerge as single, straight, dirty coloured, cylindrical rods out of the sheath. Upper leaves and sheath leaves can also be distorted and appear silvery. The white mycelium form narrow stripes along the veins. No grains are formed on the affected ear.
Occur in severe forms in many parts of South India. The disease incidence is less severe on very early and late sown crops. Presence of the fungi on seeds or on leaves of rice and other hosts in the surroundings before planting. Fungal spores surviving in the debris left after harvest and being carried by wind or water. The fungus also has grasses Isachne elegans, Cynadon dactylon, Pennisetum sp., and Eragrostis tenuifolia as collateral hosts.Warm temperature and high humidity. Of all plant stages, planting and seedling development are the most affected. However, symptoms may first become evident at the time of panicle emergence.
Hot water treatment of the seeds at 50-54°C for 10 minutes before sowing gives effective control of the disease. Solar treatment of seeds is also effective in killing the pathogen carried in the seeds.
Always consider an integrated approach with preventive measures together with biological treatments if available. Seed treatment with captan or thiram can be used. Different combinations of carbendazim, benomyl, aureofungin (a fungicidal antibiotic), iprobenfos and mancozeb reduced disease intensity and also sometimes increased grain yield in different varieties of rice. Soil treatments with carbendazim, thiram alone or followed by quintozene were better than seed treatments in reducing the incidence of Udbatta disease and increasing yield in rice.