Impact of rice harvest on diapausing yellow stem borer, scirpophaga incertulas (walker) populations
The cffcct of transplant aman and dccpwatcr rice harvest on diapausing populations of ricc yellow stem borer, Scirpophaga incertulas (Walker), werc studied during 1983-85 in Bangladesh. Harvcstivng of decpwatcr rice rcmovcd only 12% of borcrs from thc field with straw of 83 cm long but had no ctTcct at on borers in transplant aman harvcstcd at 15 cm height. It might bc possible to rcducc 20% of S. incertulas diapausing larvae from the field by increasing the harvcstcd dccpwatcr rice straw length from 83 cm to 100 cm without affccting the straw quality as cattlc feed, but reduction would not bc possible by the manipulation of harvcstcd straw lcngth in transplant aman rice. During the winter, S. incertulas remained in thc stubblc on an avcragc 110 cm awav from the base of dccpwatcr rice but below the soil surface in transplant aman stubblc. The prcscnt practicc of destroying most dccpwatcr ricc stubblc by burning during March-April has littlc cffcct on borer populations as moths cmcrgc carlicr (February-March). To dcrivc benefit, stubbles arc to bc dc.strovcd in a largc scalc by thc end of January. An casv and economic mcthod of destruction of short and isolated transplant aman stubblc is nccdcd.
- Vol-1 1991