草坪草币斑病菌对甲基硫菌灵、异菌脲和丙环唑的敏感性

Sensitivity of Sclerotinia homoeocarpa from turfgrass to thiophanate-methyl,iprodione and propiconazole

依据鉴别浓度检测了中国不同地理来源的114株草坪草币斑病菌对甲基硫菌灵的敏感性,并采用菌丝生长速率法测定了供试菌株对异菌脲和丙环唑的敏感性。结果显示:对甲基硫菌灵敏感的菌株共98株,占总数的85.96%,抗性菌株16株,占总数的14.04%;在8个有甲基硫菌灵施药历史的采样点中,5个点检测到了抗性菌株。异菌脲和丙环唑对草坪草币斑病菌的EC50值分别在0.012 1~1.264 4和0.000 4~0.100 4μg/m L之间,平均EC50值分别为(0.525 6±0.207 7)和(0.015 2±0.020 1)μg/m L,最大EC50值和最小EC50值分别相差104.7和251.0倍。敏感性频率分布结果显示,币斑病菌对异菌脲和丙环唑已出现敏感性下降的亚群体。与从未施过相关药剂地区的币斑病菌群体相比,分离自8个有施药历史地块的菌株群体对异菌脲的敏感性均显著降低,4个有施药历史地块的群体对丙环唑的敏感性显著降低。相关性分析显示,对丙环唑最不敏感的10株币斑病菌对异菌脲的敏感性均呈现下降趋势,且两者间存在一定的正相关关系(ρ=0.755 4,P<0.000 1),推测这部分菌株可能存在多药抗药性。本研究结果可为杀菌剂的合理使用及币斑病的有效防治提供理论支持。

Sensitivity of 114 Sclerotinia homoecarpa isolates to thiophanate-methyl was assayed by discriminatory concentration, and sensitivity of the tested isolates to iprodione and propiconazole was determined by mycelial growth method. 98（85.96%） and 16（14.04%） of the 114 isolates were sensitive and resistant to thiophanate-methy respectively, resistance was detected in 5 out of the 8 sampling locations with the history of fungicide applications. The range and mean EC50 values of S. homoeocarpa isolates were 0.012 1 to 1.264 4 and（0.525 6 ± 0.207 7） μg/m L for iprodione, 0.000 4 to 0.100 4 and（0.015 2 ± 0.020 1） for propiconazole. The highest EC_（50） value was 104.7 and 251.0 times greater than the lowest one for iprodione and propiconazole respectively.The results of the frequency analysis revealed that subpopulation with less sensitivity to iprodione and propiconazole had been discovered.The average EC50 values of iprodione from all the eight locations with fungicide application history showed significant difference compared to the sensitive population, while those of propiconazole from 4 locations with fungicide application history showed significant difference. Correlation analysis revealed that the 10 isolates with the least sensitivity to propiconazole were also less sensitive to iprodione, and positive correlation between iprodione and propiconazole was observed in these isolates（ρ = 0.755 4,P〈 0.000 1）, which indicates a possibility of multi-drug resistance in these isolates. The results will serve a useful reference for appropriate application of fungicides and effective control of dollar spot.