WHITE STEM BORER DAMAGE AND GRAIN-YIELD IN IRRIGATED RICE IN WEST JAVA, INDONESIA

Factors influencing the relationship between whiteheads caused by the white stem borer Scirpophaga innotata (Walker) and grain yield were in vestigated. We determined the effect of different numbers of whitehead s on grain yield using different cultivars, nitrogen application, and at different field locations in Cilamaya, West Java. At the same numbe r of panicles and whiteheads per plant, yield reduction is greater in cisadane than in IR64. With increasing nitrogen application, the range in panicle height increased. Except for Ketan, more whiteheads were r ecorded in shorter panicles. Two locations planted to the same cultiva r showed different relationships between whiteheads and grain yield. T he relationship between whiteheads and grain yield depends on the dist ribution of whiteheads in the field. Unless these factors have been ta ken into consideration, it may be difficult to make a damage predictio n of white stem borer in the field. (C) 1997 Published by Elsevier Sci ence Ltd.