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研究了8种杀菌剂5种浓度对褐飞虱2、3龄若虫的直接杀伤作用和毒力大小。杀伤试验结果表明，异稻瘟净即使在1／4倍常规推荐浓度（43．75mL／667m2）下，对褐飞虱2、3龄若虫杀伤作用也很明显。甲基立枯磷除1／4倍常规浓度（25mL／667m2）下对褐飞虱2、3龄若虫杀伤作用不明显外，在50、100、200、400mL／667m2的浓度下，于第3天开始均有显著的杀伤作用。4倍常规推荐浓度的叶枯灵（600g／667m2）、井岗霉素（500mL／667m2）、三环唑（400g／667m2）、叶青双（400g／667m2）对褐飞虱的2、3龄若虫的杀伤在第1天很小，在第3、5、7天与对照差异显著，其它各浓度均无明显杀伤作用，但百菌清、多菌灵各浓度对褐飞虱杀伤作用不明显。毒力测定结果表明，异稻瘟净对褐飞虱2、3龄若虫的毒力回归式为Y=3．7124＋3．3248X（r=0．9742），致死浓度LC30=417．28mg/kg。
The direct killing effect and virulence of 8 fungicides at 5 concentrations on the 2nd and 3rd instar nymphs of BPH were studied. The results of the killing test showed that the killing effect of the third generation nymphs of N. lugens was significantly different even at 1/4 times of the conventional recommended concentration (43.75mL / 667m2). In addition to the second and third instar nymphs of the brown planthopper, the effect of methylpulclite on the 2nd and 4th instar nymphs was not obvious at the concentration of 50, 100, 200, 400mL / 667m2, on the third day Have significant killing effect. Four times the conventional recommended concentration of leaf killer (600g / 667m2), Jinggangmycin (500mL / 667m2), tricyclazole (400g / 667m2), Yeqing double (400g / 667m2) It was very small on the first day and significant difference with the control on the 3rd, 5th and 7th day. There was no significant killing effect on other concentrations. However, the killing effect of chlorothalonil and carbendazim at each concentration was not obvious. The results of virulence test showed that virulence regression of different isolates of Pyricularia oryzae to the second and third instar nymphs of the BPH were Y = 3.7124 + 3.3248X (r = 0.9742) and lethal concentration LC30 = 417.28mg / kg.