Disease and Insect Resistance in Hybrid Rice

Abstract

The rice crop is affected by many serious diseases and insect pest problems caused by reduced genetic variability, improved cultural practices and continuous rice cropping—factors for increased rice production. Although the exact number of rice diseases in the world is difficult to determine because of the uncertain nature of some and misidentification of others, 45 fungal diseases (Ou 1972; Phytopafthological Society of Japan 1975), 10 bacterial diseases (Ou 1972), 15 virus and virus-like diseases (Ling 1979) and six nematode diseases (Ou 1972; Birchfield et al. 1978) are well characterized. Similarly, about 100 insect species attack rice crops, and 20 of these, including different species of stemborer, planthopper, leafhopper, gall midge, etc., are of great economic importance (Khush 1984).