河北省梨树褐斑病菌对苯醚甲环唑的敏感性

 为明确河北省梨树褐斑病菌(Septoria piricola Desm) 对苯醚甲环唑的敏感性,采用菌丝生长速率法测定了苯醚甲环唑对从该省11个地市分离的133 株菌株的毒力,通过方差及聚类分析法对测定结果进行了分析,并分别研究了苯醚甲环唑与双胍三辛烷基苯磺酸盐、吡唑醚菌酯、戊唑醇敏感性的相关性。结果显示:梨树褐斑病菌对苯醚甲环唑菌丝生长的最低抑制浓度为3 μg·mL^-1;供试133株菌株对苯醚甲环唑的EC₅₀范围在0.032 2~1.882 2 μg·mL^-1 之间,平均EC₅₀为(0.488 8 ±0.003 9) μg·mL^-1;敏感性频率分布图显示,病菌群体中存在着对苯醚甲环唑敏感性较低的亚群体,但 81.95% 供试菌株敏感性频率呈正态分布,将此部分菌株的 EC₅₀平均值为(0.319 3±0.001 8) μg·mL^-1 作为梨树褐斑病菌对苯醚甲环唑的敏感性基线。方差分析及聚类结果均显示,不同县市内的菌株对苯醚甲环唑EC₅₀的最大值和最小值之比为1.7~7.5;各县市的菌株对苯醚甲环唑敏感性不同,苯醚甲环唑EC₅₀平均值变化范围在0.207 4~0.961 2 g·mL^-1 之间,最大值是最小值的4.6倍;梨树褐斑病菌对苯醚甲环唑的敏感性与其对双胍三辛烷基苯磺酸盐、吡唑醚菌酯的敏感性之间无明显相关性,与戊唑醇的敏感性之间存在相关性,苯醚甲环唑与双胍三辛烷基苯磺酸盐、苯醚甲环唑与吡唑醚菌酯可以复配使用。表明河北省梨树褐斑病菌群体中尽管存在着敏感性较低的亚群体,但可通过药剂复配进行防控。

Sensitivity of Septoria piricola Desm isolates from pear to difenoconazole in Hebei Province

In order to detect the sensitivity of Septoria piricola Desm isolates from pear in Hebei Province to difenoconazole, 133 S. piricola isolates were collected from 11 counties in 2018, and their sensitivities to difenoconazole were determined by measuring the mycelial growth on the fungicide amended media. Then the data were analyzed using the least significant difference (LSD) and the cluster in Data Processing System (DPS). The sensitivities to iminoctadine trialbesilate, pyraclostrobin and tebuconazole were also determined to analyze the correlation efficient between difenoconazole and these three fungicides. The results showed that the concentration of difenoconazole that could inhibit the mycelial growth totally was 3 μg·mL^-1. The EC₅₀ values of all the tested isolates to difenoconazole were ranged from 0.032 2 to 1.882 2 μg·mL^-1 with the average EC₅₀ value at (0.488 8±0.003 9) μg·mL^-1. The results of the sensitive frequency analysis revealed that there was subpopulation with low sensitive to difenoconazole. 81.95% of all isolates showed a normal distribution and the mean EC₅₀ value of these isoaltes (0.319 3±0.001 8)μg·mL^-1 was treated as the sensitive baseline of S. piricola to difenoconazole. The ratios of the maximum and minimum EC₅₀ values of isolates from different regions were ranged from 1.7 to 7.5. However, there was difference on the sensitivity to difenoconazole among the isolates form different regions, with the mean EC₅₀ values ranged from 0.207 4 to 0.961 2 μg·mL^-1 and the ratio of maximum and minimum of average EC₅₀ values at 4.6. There were no correlations of between difenoconazole-iminoctadine trialbesilate and difenoconazole-pyraclostrobin, correlation was found between difenoconazole and tebuconazole. Although there was low sensitive S. piricola subpopulation to difenoconazole in the field, difenoconazole could still be used to control S. piricola in combination with pyraclostrobin or iminoctadine trialbesilate.