Estación Experimental La Mayora (CSIC), Algarrobo-Costa, Málaga, Spain.
Pest Manag Sci. 2010 Jul;66(7):801-8. doi: 10.1002/ps.1948.
Cucurbit powdery mildew elicited by Podosphaera fusca (Fr.) U Braun & N Shishkoff limits crop production in Spain. Disease control is largely dependent on fungicides such as sterol demethylation inhibitors (DMIs). Fungicide resistance is an increasing problem in this pathogen. To overcome such risk, it is necessary to design rational control programmes based upon knowledge of field resistance. The aim of this study was to investigate the state of DMI sensitivity of Spanish P. fusca populations and provide tools for improved disease management.
Using a leaf-disc assay, sensitivity to fenarimol, myclobutanil and triadimenol of 50 isolates of P. fusca was analysed to determine discriminatory concentrations between sensitive and resistant isolates. As no clearly different groups of isolates could be identified, discriminatory concentrations were established on the basis of maximum fungicide field application rate, 100 mg L(-1) for the three fungicides tested. Subsequently, a survey of DMI resistance was carried out in different provinces located in the south central area of Spain during the cucurbit growing seasons in 2002, 2003 and 2004. Examination of a collection of 250 isolates revealed that 23% were resistant to fenarimol and 7% to triadimenol, the provinces of Almería, Badajoz and Murcia being the locations with the highest frequencies of resistance. By contrast, no resistance to myclobutanil was found.
Results show that fenarimol and, to a lesser extent, triadimenol have become less efficient for controlling cucurbit powdery mildew in Spain. These are important observations that should lead to reconsideration of the current disease management programmes.
由瓜白粉病菌（Podosphaera fusca）引起的瓜类白粉病限制了西班牙的作物产量。疾病控制在很大程度上依赖于杀菌剂，如甾醇脱甲基抑制剂（DMIs）。这种病原体的抗药性问题日益严重。为了克服这种风险，有必要根据田间抗性知识设计合理的控制方案。本研究旨在调查西班牙 P. fusca 种群对 DMI 的敏感性状况，并提供改进疾病管理的工具。
采用叶盘法分析了 50 个 P. fusca 分离物对 Fenarimol、Myclobutanil 和 Triadimenol 的敏感性，以确定敏感和抗性分离物之间的区分浓度。由于无法确定明显不同的分离物群体，因此根据三种杀菌剂的最大田间应用率（100mg/L）确定了区分浓度。随后，在 2002、2003 和 2004 年的葫芦科作物生长季节，在西班牙中南部的不同省份进行了 DMI 抗性调查。对 250 个分离物的收集进行检查发现，23%的分离物对 Fenarimol 具有抗性，7%的分离物对 Triadimenol 具有抗性，Almería、Badajoz 和 Murcia 是抗性频率最高的省份。相比之下，没有发现对 Myclobutanil 的抗性。
结果表明，在西班牙，Fenarimol 和在较小程度上 Triadimenol 控制瓜类白粉病的效果已经降低。这些重要的观察结果应该导致重新考虑当前的疾病管理方案。
