Effect of date of transplanting and nitrogen doses on development of sheath blight in basmati type rice cv. Pusa 1121

Effect of high nitrogen dose and date of transplanting on development and spread of sheath blight was studied in basmati type rice cv. Pusa 1121 during Kharif 2011. Nitrogen was applied @ 0, 18, 36,54 and 72 kg urea/acre. An initial increase in N supply corresponds to an increase in yield, but at the highest N level, a reduction in yield was observed as the severity of blighted sheaths increased in the plots receiving higher dosages of nitrogen as compared to those receiving less or no nitrogen. Different nitrogen levels had significant effect on plant height, total number of tillers per plant, and plant girth and disease severity. Increased N supply resulted in increase in host plant tissue contacts, whether leaf to leaf or leaf to sheath. Plant girth, total number of tillers/plant and disease severity were maximum in 72 kg urea/acre treatment. However, maximum grain yield was recorded in plots supplied with 36kg urea/acre.