烟草黑胫病菌对三种内吸性杀菌剂的敏感性测定

Determination on sensitivity of Phytophthora nicotianae var. nicotianae to three systemic fungicides

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。

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 ECso values ranged from 0.0867μg/mL to 1. 6781 μg/ mL, from 24. 042 μg/mL to 62. 663 μg/mL and from 60.468 μg/mL to 239.51 μg/mL and the mean ECso values （ ±Sex to. 05 ） were 0. 2991 ± 0. 0842 μg/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, eymoxanil and fosetyl-Al in Phytophthora nicotianae var. nicotianae and no resistant subeolony had been discovered. The mean EC50 values （ ± Se× t0.05 ） of metalaxyl, eymoxanil 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. 6497 μg/mL. They could be used as the baselinessensitivity to metalaxyl, eymoxanil and fosetyl-Al of Phytophthora nicotianae var. nicotianae respectively.