苜蓿根腐病的病原分离、鉴定与杀菌剂毒力测定

为了解河北苜蓿根腐病病原种类,以便有目的地加以防治,对从河北采集的苜蓿根腐病样品进行了病原分离、鉴定以及致病性和室内毒力测定。根据形态学和核糖体内转录间隔区ITS4和ITS5、延伸因子EF-1H和EF-2T序列作为引物鉴定,分离出的71株致病菌株均为镰孢菌属(Fusarium),其中,木贼镰孢(F.equiseti)55株,尖孢镰孢(F.oxysporum)7株,层出镰孢(F.proliferatum)6株,变红镰孢(F.incarnatum)2株,茄镰孢(F.solani)1株。尖孢镰孢菌株D19-2、层出镰孢菌株S45和茄镰孢菌株Q1的致病性最强。通过含毒介质法测定,结果表明,40%腈菌唑可湿性粉剂(WP)、50%多菌灵WP、嘧环·咯菌腈(37%嘧菌环胺和25%咯菌腈)水分散粒剂(WDG)、50%福美双WP、70%甲基硫菌灵WP和10%苯醚甲环唑WDG对这3个菌株菌丝生长均有较好抑制作用,而80%代森锰锌WP、99%恶霉灵WP、40%菌核净WP的抑制作用较弱。

Isolation, identification and toxicity determination of pathogens causing alfalfa root rot

To discover the pathogens causing alfalfa root rot in Hebei Province, China, and to provide references for prevention and control of the disease, isolation, identification and indoor pathogenicity test of pathogens from the samples of alfalfa root rot collected in Hebei Province were conducted, and toxicity determination of fungicides for controlling the disease was investigated.A total of 71 pathogenic strains were isolated from the diseased tissues and were identified as Fusarium strains by using the morphological identification method and molecular biological identification method with the ribosomal internal transcribed spacers (ITS4 and ITS5) and extension factors (EF-1H and EF-2T) as the primers for PCR amplification, respectively.The identification results obtained by using the morphological identification method and the molecular biological identification method were consistent.The results showed that the 71 strains of Fusarium included 55 strains of F.equiseti, seven strains of F.oxysporum, six strains of F.proliferatum, two strains of F.incarnatum and one strain of F.solani.The pathogenic determination results demonstrated that strain D19-2 of F.oxysporum, strain S45 of F.solani and strain Q1 of F.proliferatum had the strongest pathogenicity among all of 71 strains. The sensitivity of the three strongest pathogenic strains (including D19-2, S45 and Q1) to 40% myclobutanil wettable powder (WP), 50% carbendazim WP, 99% hymexazol WP, 40% dimetachlone WP, cyprodynil·fludioxonil (37% cyprodynil and 25% fludioxonil) water dispersible granule (WDG), 50% thiram WP, 80% mancozeb WP, 70% thiophanate-methyl WP and 10% difenoconazole WDG, was determined using the poison medium method.The results indicated that 40% myclobutanil WP, 50% carbendazim WP, cyprodynil·fludioxonil WDG, 50% thiram WP, 70% thiophanate-methyl WP and 10% difenoconazole WDG had better inhibitory effects on mycelia growth of the three strains than the other three types of fungicides.