Abstract: Isolates of Bipolaris sorokiniana and B.coicis from diseased barnyardgrass(Echinochloa crus-galli) plants in Kunming,Yunnan Province were evaluated for their potentials against barnyardgrass as biocontrol agent.The results of bioassay showed that the 5-day culture filtrates of the two strains had high inhibitory activity to the growth of barnyardgrass,with the inhibitory rates of 99.59% and 95.78% on roots,91.14% and 82.13% on buds,respectively.And the barnyardgrass treated with mycelium suspension of the two strains showed 100% disease incidence in the laboratory experiment.In greenhouse,the barnyardgrass plants showed the defoliating of leaves,the wilting of shoots and the death of plants after 7 days treatment by the mycelium suspension from the two strains,and the mortality rate added up to 82.67% for B.sorokiniana and 80.00% for B.coicis respectively at 21 days after treatment.In addition,the crop safety test showed that B.sorokinina was safer to major crops than B.soicis and had a better application prospect as bio-agent.

Key words: Bipolaris sorokiniana, Bipolaris coicis, Echinochloa crus-galli, rice(Oryza sativa), biological control

摘要： 对分离自云南昆明感病稗草\[Echinochloa crusgalli (L.) Beauv.\]上的病原真菌麦根腐平脐蠕孢（Bipolaris sorokiniana）和薏苡平脐蠕孢（Bipolaris coicis）开展了防治稗草潜力的评价。结果显示，B.sorokiniana和B.coicis两菌株培养5 d的发酵原液对稗草根长和芽长均有很高的抑制作用,根长最高抑制率分别为99.59%和95.78%, 芽长最高抑制率分别为91.14%和82.13%。两菌株对稗草离体叶片致病性的室内试验表明，菌丝体悬浮液处理5 d后稗草叶片病情指数最高可达100%。两菌株对稗草植株防效的温室试验表明, 菌丝体悬浮液处理稗草7 d后植株下部叶片出现萎蔫症状、脱落及死亡,处理21 d后稗草最高死亡率达到82.67%和80.00%。菌株对作物的安全性试验表明，麦根腐平脐蠕孢对作物的安全性显著高于薏苡平脐蠕孢。作为生防潜力菌株，麦根腐平脐蠕孢具有更大的应用潜力。

关键词: 麦根腐平脐蠕孢, 薏苡平脐蠕孢, 稗草, 生物防治