河北省梨树褐斑病菌对不同机制杀菌剂的敏感性及其与戊唑醇敏感性的关系

为明确河北省梨树褐斑病菌(Septoria piricola Desm)对戊唑醇和双胍三辛烷基苯磺酸盐、吡唑醚菌酯、环丙唑醇等不同作用机制杀菌剂的敏感性及交互抗性,采用室内菌丝生长速率法和田间小区试验分别测定了不同杀菌剂对11个地市分离到的133株病菌菌株的毒力,以及对梨树褐斑病的防治效果,研究了病菌对戊唑醇与对双胍三...

Sensitivity of Septoria piricola Desm from pear in Hebei Province to different classes of fungicides and correlation coefficient with tebuconazole

Resistance detecting and monitoring are critical to manage the fungicides and pathogen populations. We collected 133 isolates of Septoria piricola Desm from pear from 11 counties in Hebei Province. The sensitivities to tebuconazole, iminoctadine trialbesilate, pyraclostrobin and cyproconazole were determined by the mycelial growth method in the laboratory. The correlation between tebuconazole and iminoctadine trialbesilate, pyraclostrobin and cyproconazole were further evaluated. The results showed that EC₅₀ values of tebuconazole for all isolates ranged from 0.0392 to 2.0522 μg·mL^-1 with the average at 0.5486±0.0012 μg·mL^-1. The ratio of lowest and highest EC₅₀ values of tebuconazole for the isolates from the different regions ranged from 2.7 to 7.4. All the isolates did not exhibit the significant difference on the sensitivity to tebuconazole with the average EC₅₀ values from 0.1639 to 0.9124 μg·mL^-1. In compare with the baseline sensitivities for mycelia growth of S. piricola to iminoctadine trialbesilate and pyraclostrobin with the average values of 0.2621±0.0014 μg·mL^-1 and 0.2750±0.0017 μg·mL^-1, respectively, there was no significant correlation of sensitivity between tebuconazole and iminoctadine trialbesilate, pyraclostrobin, while correlation to cyproconazole. Therefore, tebuconazole and iminoctadine trialbesilate, tebuconazole and pyraclostrobin can be mixed, and the best mix ratio is 1∶6 and 4∶1, respectively. The control efficacy, compared with the single fungicide application for pear brown spot caused by S. piricola, was significant differences between tebuconazole + iminoctadine trialbesilate (30+180 μg·mL^-1) and tebuconazole + pyraclostrobin (100+25 μg·mL^-1) that was 95.49%, 93.48% in 10 days after spraying application just once, and 86.51%, 87.40% or 69.02%, 70.33% in 10 or 50 days after the third applications, respectively. The combination of the fungicides displayed a significantly better effectiveness and duration of protection than with their use only.