１９９２～１９９４年，分别以水稻辽盐２、辽盐２４１、辽粳５和辽开７９─３为试材，于水稻收获期按纹枯病情分级采集病穗标本，进行产量损失测定。结果表明：水稻穗重和病情严重度呈负相关，病害所致产量损失和病情呈正相关；比较３年４个品种间的测定结果，产量损失和病情的关系趋于一致；初步研究认为，纹枯病２级病情可定为病害损失和防治阈值。 From 1992 to 1994, the samples of diseased ears of Liaoyan 2, Liao salt 241, Liaojing 5 and LiaoKai 79─3 were collected at the harvest stage of rice paddy according to the severity of the sheath blight, and the yield loss was measured. The results showed that there was a negative correlation between the panicle weight and the severity of the disease, and the yield loss caused by the disease was positively correlated with the disease. The results of the comparison between the four varieties in three years showed that the relationship between the yield loss and the disease tended to be the same. Grade 2 disease can be identified as disease damage and control threshold.