Abstract: A field trial was conducted under natural ecological conditions and regular management to evaluate the effect of the rice leaffolder, Cnaphalocrocis medinalis, damage on the yield of early-season hybrid rice (Shanyou 402) by artificial defoliation. Foliar area of plants were cut off at the rate of 5%-30% at early tillering, peak tillering, elongation, booting, and milky stage, respectively, with each treatment including four 1 m² replications. The average yields from the plots defoliated at peak tillering were significantly higher than that of the control whereas the yields from the plots defoliated at the milky stage were lower than that of the control. Thus, the hybrid plants were apparently tolerant to foliar injury at tillering. This indicates that the current control thresholds recommended for the leaffolder should be reevaluated and that no spray one month after transplanting should be an acceptable practice for the strategy of the leaffolder control.

Key words: Cnaphalocrocis medinalis, control thresholds, hybrid rice, rice leaffolder

关键词: 稻纵卷叶螟, 食叶性害虫, 防治指标