摘 要 ：采用菌落生长速率法测定了2005年从云南、贵州、山东烟区病株上分离到的38个烟草黑胫病菌Phytophthora nicotianae var. nicotianae菌株对三种内吸性杀菌剂的敏感性。结果表明:甲霜灵、霜脲氰和乙膦铝对38个菌株的EC50值均呈单峰频次分布,分别分布在0.0867~1.6781、24.042~62.663和60.468~239.51μg/mL之间,均值分别为0.2991±0.0842、35.891±2.7823和105.73±11.154μg/mL;烟草黑胫病菌对甲霜灵、霜脲氰和乙膦铝的敏感性高,未出现敏感性下降的抗药性亚群体。敏感性频次分析结果表明:甲霜灵、霜脲氰和乙膦铝分别对组成连续单峰频次分布的34、37、37个菌株的EC50均值为0.2389±0.0292、35.167±2.4317、102.11±8.6497μg/mL,可分别作为烟草黑胫病菌对甲霜灵、霜脲氰和乙膦铝的敏感性基线。
Abstract:The sensitivities to metalaxyl, cymoxanil and fosetyl-Al of the 38 strains of Phytophthora nicotianae var.nicotianae collected from tobacco plants in Yunnan, Guizhou, Shandong, China in 2005 were determined with the method of colonial growth-rate. The frequency distributions of EC50 values to the 38 strains of three fungicides were all unimodal and the EC50 values ranged from 0.0867μg/mL to 1.6781μg/mL, from 24.042μg/mL to 62.663μg/mL and from 60.468 μg/mL to 239.51μg/mL and the mean EC50 values (±Se×t0.05) were 0.2991±0.0842μg／mL, 35.891±2.7823μg/mL and 105.73±11.154μg/mL respectively. The results of frequency-analysis showed that there were high sensitivities to metalaxyl, cymoxanil and fosetyl-Al in Phytophthora nicotianae var. nicotianae and no resistant subcolony had been discovered. The mean EC50 values (±Se×t0.05) of metalaxyl, cymoxanil and fosetyl-Al to the 34, 37, 37 strains, which composed the continuous unimodal distributions-sensitivity, were 0.2389±0.0292μg/mL, 35.167±2.4317μg/mL and 102.11±8.6497μg/mL. They could be used as the baselines-sensitivity to metalaxyl, cymoxanil and fosetyl-Al of Phytophthora nicotianae var.nicotianae respectively.