Department of Plant and Environmental Sciences, Coastal Research and Education Center, Clemson University, Charleston, SC 29414.
Plant Dis. 2019 Oct;103(10):2592-2598. doi: 10.1094/PDIS-02-19-0323-RE. Epub 2019 Jul 26.
The objective of this study was to evaluate fungicide applications, host resistance, and trellising, alone and in combination, as management practices for downy mildew on slicing cucumber. A split-split plot experimental design was used with three and four replications in spring and fall 2017, respectively. The whole-plot treatment was fungicide, four applications of chlorothalonil (Bravo Weather Stik 6SC) alternated with three applications of cyazofamid (Ranman 400SC), or water. Split plots were nontrellised or trellised with four strings supported by stakes. Split-split plots were cultivar Bristol, which is intermediately resistant to downy mildew, or cultivar Speedway, which is susceptible to downy mildew with similar parentage as Bristol. In both seasons, area under the disease progress curve (AUDPC) values were lower with fungicides than water for both cultivars. In the spring, AUDPC for Bristol was lower than for Speedway regardless of fungicide treatment. In the fall, Bristol had a lower AUDPC than Speedway with fungicides, but the AUDPC did not differ between the two cultivars with water. The mean AUDPC for trellised plants (376.2) was lower than for nontrellised plants (434.0; = 0.007). Fungicide applications increased marketable and total fruit weights in both seasons ( ≤ 0.0002). Marketable weight with fungicides was almost double (93% greater) the marketable weight with water. Marketable weight was 55% greater for Bristol than for Speedway in spring, but yields did not differ between cultivars in fall (season-by-cultivar interaction, ≤ 0.0003). Because trellising had no effect on marketable yields ( = 0.11), trellising is not recommended for managing downy mildew on slicing cucumber. Of the three management techniques examined, fungicides had the largest effects on disease and yields, followed by cultivar resistance.
本研究旨在评估杀菌剂应用、寄主抗性和棚架栽培单独及组合使用作为防治切片黄瓜霜霉病的管理措施。采用裂区-裂区-裂区试验设计，春季和秋季分别进行了三次和四次重复。主处理为杀菌剂，交替使用四次氯噻啉（Bravo Weather Stik 6SC）和三次氰霜唑（Ranman 400SC），或清水。副区为未棚架和棚架栽培，用 4 根绳子支撑在桩上。裂-裂-裂区为中抗霜霉病的布里斯托尔品种或与布里斯托尔亲缘关系相近的感病品种斯帕达速度。在两个季节中，与清水相比，杀菌剂处理下的两种品种的病情指数曲线下面积（AUDPC）值均较低。在春季，无论杀菌剂处理如何，布里斯托尔的 AUDPC 均低于斯帕达速度。在秋季，杀菌剂处理下布里斯托尔的 AUDPC 低于斯帕达速度，但清水处理下两个品种的 AUDPC 没有差异。棚架栽培的平均 AUDPC（376.2）低于无棚架栽培的平均 AUDPC（434.0； = 0.007）。杀菌剂处理在两个季节均增加了可销售和总产量（ ≤ 0.0002）。杀菌剂处理下的可销售产量几乎是清水处理的两倍（增加 93%）。春季布里斯托尔的可销售产量比斯帕达速度高 55%，但秋季两个品种的产量没有差异（季节-品种互作， ≤ 0.0003）。由于棚架栽培对可销售产量没有影响（ = 0.11），因此不建议在切片黄瓜上使用棚架栽培来防治霜霉病。在所研究的三种管理技术中，杀菌剂对疾病和产量的影响最大，其次是寄主抗性。
