Abstract

                                The blast disease of rice caused by Piricularia oryzae Cav. is a disease of great economic importance in South India. The intensity of its incidence and the severity of the damage caused by it are profoundly infinonced, apart from the varietal susceptibilty, by several environmental factors. Among these, the factor relating to the nutrition of the host plant is of considerable practical importance to the rice grower. Previous investigations in Coimbatore by Thomas (1932) and in Japan by Suzuki (1335) and Sawada (1937) have shown that application of heavy doses of nitrogonous manures is conducive to the development of the disease. With a view to obtaining further information relating to this aspect a series of field experiments were carried out as part of the programine of a special scheme sponsored by the Indian Council of Agricultural Research for the investigation of blast and foot-rot disease. of rice in the Madras State. In this paper an nccount is given of the experiments enrried out during the last seven years with the object af determining the effect of application of varying levels of nitrogen phosphorus and potash on the incidence of blast in different varieties of rice.

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