Seasonal incidence of rice stem borer, Scirpophaga incertulas (Walker) on different varieties of rice in relation to weather parameters

Abstract

Transplanting of eight paddy varieties (PR-113,HKR-47,NDR-359, Sarju-52,PS-4,PS-5,PS-15 and PS-21) was done on 11th july 2016 during Kharif season for investigate the seasonal incidence of rice stem borer, Scirpophaga incertulas (Walker) on different varieties of paddy. Dead heart started from 32th standard week and continued upto 38th standard week, while white ear head was recorded on 35th standard week and it reached peak in 45th standard week .On the basis of peak infestation period, the maximum dead heart was recorded on PS-15(30.3%) while, minimum dead heart was found in HKR-47(14.6%) variety of paddy. The white ear head percent was ranged from 27% to 44.9%. Varietal reaction did not play a prominent role for the high or low stem borer incidence. Relationship of weather parameters indicated that they play a major role in creating the variation in S. incertulas prevalence. Temperature and relative humidity conducive during the cropping season, wide variation was recorded in the amount of rainfall and its distribution in along with the variation in sunshine hour. High rainfall during, August with low sunshine hours in September, followed by gradual decrease of rainfall with increase in sunshine hours towards October resulted in more S. incertulas incidence.