Abstract

Manuring and spacing (population per unit area) were believed to have some bearing on the incidence of crop pest. Vigorous growth of the rice plant, as a result of adequate manuring and proper spacing influences the resistance of plant to the infestation of crop pest. The effect of these two agronomic practices was studied for the attack of rice stem borer (Schoeno- bius incertellus Wlk.) on a Japonica x Indica rice H. R. 104 in comparison to a local Indica rice H. R. 5. The hybrid variety is of recent origion and information on these aspects was scanty. Narayanan (1953) observed that the severity of the attack can be reduced by keeping the field bunds clean free of grasses. Khan and Murthy (1955) reported varietal susceptibility to the rice stem borer with heavy egg laying by the moth and attack to the stem by the Caterpillars. Cultivation of such varieties could be avoided to minimise the losses in yield. Rao et al. (1956) stated that no variety under trial was completely immune but varied in degree of suscepti- bility to stem boner. Experiments conducted at the Central Rice Research Institute, Cuttack (1954-55) indicated that rice crop had shown a signi- ficantly greater number of white ears in plots with high nitrogen levels compared to unmanured plots. Ahmed and Rao (1965) observed that cultural practices of spacing and seedling rate did not influence the attack of stem borer nor there was an interaction between the two practices.

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