Lehner M S, Del Ponte E M, Gugino B K, Kikkert J R, Pethybridge S J
School of Integrative Plant Science, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456.
Departmento de Fitopatologia, Universidade Federal de Viçosa, MG, 36570-900, Brazil.
Plant Dis. 2017 Jul;101(7):1253-1258. doi: 10.1094/PDIS-12-16-1731-RE. Epub 2017 Apr 27.
White mold (Sclerotinia sclerotiorum) of leguminous crops in New York is generally managed with preventive applications of fungicides. However, no research has been conducted during the last decade to assess the sensitivity of the S. sclerotiorum population to fungicides or compare their performance under field conditions. The sensitivity of S. sclerotiorum to boscalid, fluazinam, and thiophanate-methyl was assessed in 151 isolates from 15 fields across New York using an agar dilution method with discriminatory concentrations. In addition, the effective concentration at which mycelial growth is reduced by 50% (EC) was estimated for one representative isolate from each field. The efficacy of commercial formulations of each fungicide on white mold incidence in plants and pods was also tested in two field trials (2015 and 2016). The EC values ranged from 0.068 to 0.219, 0.001 to 0.002, and 1.23 to 2.15 µg/ml for boscalid, fluazinam, and thiophanate-methyl, respectively. Evidence of resistance was not found using the discriminatory concentration tests. The mycelial growth inhibition relative to the control ranged from 56 to 83%, 66 to 84%, and 53 to 83% at discriminatory concentrations of boscalid (5 µg a.i./ml), fluazinam (0.05 µg a.i./ml), and thiophanate-methyl (5 µg a.i./ml), respectively. Fourteen isolates with mycelial growth inhibition lower than 60% at 5 µg/ml of thiophanate-methyl, did not exhibit point mutations within a partial sequence of the β-tubulin gene. In the field trials, fungicides effectively reduced white mold incidence on plants by 75% (2015) and 93% (2016) and on pods by 81% (2015) and 87% (2016), both relative to the nontreated plots. However, fungicide applications led to significant increases in pod yield, relative to the nontreated plots, only in 2015 when the incidence of white mold on plants and pods were higher (85 and 49.2%) than in 2016 (31.3 and 10.3%). Although fungicide resistance was not detected, and thus control failures reported by New York snap bean growers may be due to other factors, further monitoring of sensitivity within the S. sclerotiorum population is encouraged as well as the use of rational systems to base their judicious and economic use.
纽约豆科作物的白霉病（核盘菌）通常通过预防性施用杀菌剂来控制。然而，在过去十年中尚未开展研究来评估核盘菌种群对杀菌剂的敏感性，或比较它们在田间条件下的表现。使用具有区分浓度的琼脂稀释法，对来自纽约15个田地的151个分离株进行了核盘菌对啶酰菌胺、氟唑菌酰胺和甲基硫菌灵的敏感性评估。此外，还对每个田地的一个代表性分离株估计了使菌丝体生长减少50%（EC）的有效浓度。在两项田间试验（2015年和2016年）中，还测试了每种杀菌剂商业配方对植物和豆荚上白霉病发病率的防治效果。啶酰菌胺、氟唑菌酰胺和甲基硫菌灵的EC值分别为0.068至0.219、0.001至0.002和1.23至2.15微克/毫升。使用区分浓度测试未发现抗性证据。在啶酰菌胺（5微克有效成分/毫升）、氟唑菌酰胺（0.05微克有效成分/毫升）和甲基硫菌灵（5微克有效成分/毫升）的区分浓度下，相对于对照，菌丝体生长抑制率分别为56%至83%、66%至84%和53%至83%。在甲基硫菌灵5微克/毫升时菌丝体生长抑制率低于60%的14个分离株，在β-微管蛋白基因部分序列内未表现出点突变。在田间试验中，相对于未处理地块，杀菌剂有效地将植物上的白霉病发病率降低了75%（2015年）和93%（2016年），将豆荚上的发病率降低了81%（2015年）和87%（2016年）。然而，相对于未处理地块，仅在2015年，当植物和豆荚上的白霉病发病率（85%和49.2%）高于2016年（31.3%和10.3%）时，施用杀菌剂才导致豆荚产量显著增加。尽管未检测到杀菌剂抗性，因此纽约菜豆种植者报告的防治失败可能是由于其他因素，但仍鼓励对核盘菌种群内的敏感性进行进一步监测，并使用合理的系统来明智且经济地使用杀菌剂。
