Forecasting and control of rice diseases

Abstract

The study of the relation of meteorological factors on development of rice diseases has been in progress at the Central Rice Research Institute in respect of blast, helminthosporiose and false smut. As regards blast it was found that a coincidence of low night temperature of 20-26°C and below, especially 24°C and below with high relative humidity of 90 per cent and above during the susceptible stages of the crop growth (seedling, tillering and neck emergence) was accompanied by blast outbreak. Data have been obtained to show that timely application of fungicides based on forecasting of the disease will help in effective control of the disease. Fungicides based on copper, mercury, tin and organo-phosphates (Hinosan, Kitazin) and Kasumin (antibiotic) have been found to be effective in controlling blast. On local indica varieties, application of copper fungicides has been found to be effective and economical, but on account of phytotoxicity copper cannot be recommended for use on high-yielding varieties. Fungicides like Hinosan, Kitazin or Kasurnin are suggested for high-yielding varieties. As regards helminthosporium disease, cloudy days, low sunshine hours, slight drizzle and lower range of daily temperature during the flowering to maturity of crop were associated with higher incidence of the disease. Severe incidence of false smut of rice was associated with higher percentage of relative humidity and lower maximum temperature during flowering period of rice.