白菜型冬油菜根腐病病原鉴定及室内毒力测定

引起甘肃省白菜型冬油菜根腐病的病原菌为半裸镰刀菌(Fusarium semitectum)、链格孢(Alternaria al-ternata)、尖孢镰刀菌(F.oxysprorum)、黑根霉(Rhizopus nigricans)和青霉菌(Penicilliumsp.)5种真菌,其中半裸镰刀菌和链格孢为主要致病菌,其分离频率分别为47.1%和30.9%,半裸镰刀菌和链格孢有伤接种发病率分别为90%和80%,无伤接种发病率分别为76.7%和70.0%.采用室内平皿生长速率法,研究7种杀菌剂对冬油菜根腐病的病原半裸镰刀菌和链格孢的毒力测定.结果表明:多菌灵、甲基硫菌灵、噁霉灵、代森锌、福美双、多福和丙.噁.甲霜灵7种药剂对2种病原菌都有显著的抑制作用,对半裸镰刀菌的有效中浓度(EC50)分别为17.66、16.89、0.13、1 435.20、50.84、59.03和0.53μg/mL,对链格孢菌的EC50分别为36.06、41.54、0.29、59.30、34.06、109.27和0.81μg/mL.以噁霉灵的抑菌作用最为突出,对半裸镰刀菌和链格孢菌的EC50均在0.3μg/mL以下,丙.噁.甲霜灵次之,代森锌最差.7种药剂的毒力相关系数均在0.90以上,药剂质量浓度与抑制作用呈正相关.

Identification of root rot pathogen of winter turnip rapeseed and toxicity measurement

The five pathogens causing root rot of winter rapeseed in Gansu Province were identified as Fusarium semitectum,Alternaria alternate(Fr.)Keissl.,F.oxysprorum,Rhizopus nigricans,Penicillium sp.,the main pathogens causing postharvest diseases of apricots were F.semitectum and A.alternate,the isolation frequencies of them were 47.1% and 30.9% respectively.After artificial inoculation with or without wounds,the incidence of root infected by F.semitectum and A.alternate were 90.0% and 80.0%,or 76.7% and 70.0%.With mycelium growth rate test method,the toxicity of seven fungicides to F.semitectum and A.alternate had inhibition effect,the result indicated that EC50 of Carbendazim,Thiophanate-methyl,Hymexazol,Zineb,Thiram,Thiram+carbendazim and Hymexazol+metalaxyl were 17.66、16.89、0.13、1435.20、50.84、59.03 and 0.53 μg/mL,36.06、41.54、0.29、59.30、34.06、109.27 and 0.81 μg/mL,EC50 of Hymexazol showed strong inhibitive effects on F.semitectum and A.alternate were under 0.3 μg/mL.There were significantly positive correlation between pharmacy concentration and inhibition effect.The relative coefficienes of seven fungicides were all above 0.9.