Seasonal incidence of yellow stem borer (Scirpophaga incertulas Walker) in different rice ecosystem

Field experiment was conducted at research farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur during Kharif season 2013-14 using different rice ecosystem viz. upland direct seeded, upland transplanted, lowland organic and lowland conventional rice ecosystem. The results of experiments revealed that the maximum per cent incidence of dead heart and white ear head observed during 37 SMW and 43 SMW in month of September and October respectively with 6.96 and 21.38 per cent/hill in lowland conventional rice ecosystem. Seasonal mean of dead heart and white ear head were ranged from 0.50 to 1.49 per cent and 2.76 to 6.59 per cent respectively. The correlation and regression studies revealed that only rainfall showed significant negative correlation with per cent incidence of white ear head (r = -0.581*, r= -0.589*) and influence the pest incidence with 33 per cent and 34 per cent respectively in lowland organic and conventional rice ecosystem at 1 and 5 per cent level of significance. Similarly minimum temperature (0C) and evening relative humidity (%) showed highly significant negative correlation with white ear head (r = -0.726**, r= -0.717**) influence 52 and 51 per cent in upland direct seeded ecosystem whereas, significant negative correlation with white ear head (r = -0.656*, r= -0.545*) influence 43 and 29 per cent in upland transplanted rice ecosystem.