为筛选防治西瓜炭疽病的高效低毒杀菌剂，缓解和治理生产中病菌对药剂的抗性，在室内离体条件下采用生长速率抑制法及孢子萌发抑制法测定了9种杀菌剂对西瓜炭疽病菌（Colletotrichumorbiculare）的毒力。结果表明，嘧菌酯、咪鲜胺和甲基硫菌灵对病原菌菌丝生长的EC50在0．0933～0．1182 mg／L之间，均小于1 mg／L，表明西瓜炭疽病菌对上述杀菌剂比较敏感；百菌清、烯肟菌酯和戊菌唑的EC50在2．3101～5．9259 mg／L，病菌对药剂的敏感程度相对较低；代森锰锌、恶霉灵和多菌灵的EC50分别为36．8763、74．4666和99．8985 mg／L，抑菌活性较差。孢子萌发试验中，嘧菌酯、咪鲜胺和甲基硫菌灵对病菌孢子萌发的抑制活性最高，EC50在0．0694～0．1672 mg／L之间；百菌清、烯肟菌酯、代森锰锌的抑制活性次之，EC50在1．8530～9．5039 mg／L之间；多菌灵的抑制活性相对最低， EC50为99．3353 mg／L。将两种不同作用机理的杀菌剂嘧菌酯与咪鲜胺按照2∶1的比例混配，联合毒力测定和评价结果表明两者混配对抑制西瓜炭疽病菌具有增效作用。%The effects of nine fungicides and their mixtures on Colletotrichum orbiculare were tested with the mycelium growth rate and spores germination methods in vitro in laboratory. The results showed that azoxystrobin,prochloraz and thiophanate-methyl had significant inhibition activity on mycelium growth,with the EC50 values ranged from 0.093 3 to 0.118 2 mg/L. Chlorothalonil,enestroburin and penconazole were less effective,with EC50 values between 2.310 1 and 5.925 9 mg/L. Mancozeb,hymexazol and carbendazim were least effective,with EC50 values of 36.876 3,74.466 6 and 99.898 5 mg/L,respectively. Azoxystrobin,prochloraz and thiophanate-methyl had the best inhibitory actions on the spore germination,with the EC50 values of 0.069 4-0.167 2 mg/L. Chlorothalonil,enestroburin and mancozeb had less effects(with EC50of 1.853 0-9.503 9 mg/L),while carbendazim(with EC50of 99.335 3 mg/L)took the last place. Synergistic inhibition on mycelium growth was obtained when azoxystrobin and prochloraz were mixed.
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