Impact of Cultural Practices and Nitrogenous Fertilizer on the Development of Brown Spot Disease of Rice

Among the diseases the brown spot disease of rice caused by Bipolaris oryzae is most dominant fungal disease of rice after blast (Pyricularia oryzae) which is causing losses in the yield which resulted in instability in rice production particularly in north Bihar. This disease was considered to be one of the most important facet of 1943 Bengal Famine. The losses in famine were accounted to 50-90 per cent (Ghose et al. 1960; Padmanabhan, 1973). The disease is a serious and has global distribution and it has been found in all rice growing countries in Asia, America and Africa. The studies mainly adhered to see the effect of various doses of nitrogen and different cultural practices on development of brown spot disease of rice. Among the various cultural practices, minimum (17.64%) disease seventy and maximum yield (3.13/ha) were found with application of FYM (5 t/ha) + line sowing of 60 kg seed/ha + 50% N application after 15 DAS 25 % N at maximum tillering + 25% N at panicle initiation + weed control. Doses of nitrogen were positively related with the disease development and negatively related with the grain yield indicating the maximum (38.30 % and 39.0 %) disease severity and minimum (1.86 and 1.97 t/ha) grain yield with nitrogen dose of 120 kg/ha. In respect of varietal response, the minimum (12.10 % and 16.40 %) disease severity and the maximum (4.34 t/ha and 4.58 t/ha) yield were recorded in the variety Rajshree receiving 80 kg N/ha.