Department of Plant and Soil Sciences, University of Pretoria, Hatfield, Pretoria 0001, South Africa.
University of Idaho, Parma Research and Extension Center, Parma, ID 83660.
Plant Dis. 2018 Aug;102(8):1520-1526. doi: 10.1094/PDIS-09-17-1470-RE. Epub 2018 Jun 11.
Rhizoctonia is a major pathogen of potato causing substantial yield losses worldwide. Control of Rhizoctonia diseases is based predominantly on the application of fungicides. However, little is known about the fungicide response variability of different Rhizoctonia anastomosis groups associated with potato diseases in South Africa. A total of 131 Rhizoctonia isolates were obtained from potato growing regions of South Africa from 2012 to 2014 and evaluated for sensitivity to fungicides in vitro and in vivo. The fungicides comprised six chemical formulations and one bio-fungicide representing seven Fungicide Resistance Action Committee groups. All Rhizoctonia anastomosis groups were sensitive to tolclofos-methyl (EC: 0.001 to 0.098 μg a.i. ml) and fludioxonil (EC: 0.06 to 0.09 μg a.i. ml) and showed variation in sensitivity to pencycuron, iprodione, benomyl, and Bacillus subtilis QST 713. However, for azoxystrobin, Rhizoctonia isolates exhibited variable sensitivity ranging from sensitivity (EC: <0.09 μg a.i. ml) to insensitivity with EC values exceeding 5 μg a.i. ml. In greenhouse and field trials, tolclofos-methyl and fludioxonil exhibited significantly greater control of stem and black scurf whereas azoxystrobin was the least effective. This work demonstrated variable sensitivity within and among anastomosis groups of R. solani and binucleate Rhizoctonia to different fungicides. Information on fungicide sensitivity of Rhizoctonia isolates is crucial in the development of effective Rhizoctonia control strategies and facilitates monitoring of fungicide insensitive isolates in the pathogen population.
根肿菌是一种主要的马铃薯病原菌，在全球范围内造成了大量的产量损失。对根肿菌病的防治主要依赖于杀菌剂的应用。然而，人们对与南非马铃薯病害相关的不同根肿菌吻合群的杀菌剂反应变异性知之甚少。从 2012 年到 2014 年，从南非的马铃薯种植区共获得了 131 株根肿菌分离物，并在体外和体内评估了它们对杀菌剂的敏感性。这些杀菌剂包括六种化学配方和一种生物杀菌剂，代表了七个杀菌剂抗性行动委员会小组。所有根肿菌吻合群对甲基托布津（EC：0.001 至 0.098 μg a.i. ml）和氟啶酮（EC：0.06 至 0.09 μg a.i. ml）敏感，并对戊菌隆、丙环唑、苯菌灵和枯草芽孢杆菌 QST 713 的敏感性存在差异。然而，对于肟菌酯，根肿菌分离物表现出从敏感（EC：<0.09 μg a.i. ml）到不敏感的可变敏感性，EC 值超过 5 μg a.i. ml。在温室和田间试验中，甲基托布津和氟啶酮对茎和黑腐病的防治效果显著优于肟菌酯。这项工作表明，不同吻合群的根肿菌和双核根肿菌对不同杀菌剂的敏感性存在差异。了解根肿菌分离物对杀菌剂的敏感性对于制定有效的根肿菌防治策略至关重要，并有助于监测病原菌群体中对杀菌剂不敏感的分离物。
