Abstract Cultivated American ginseng (Panax quinquifolius) is a perennial herb valued as a traditional Chinese medicine. The crop is commercially produced under polypropylene shade cloth, creating a climate favorable for leaf blight caused by Alternaria panax; frequent fungicide applications are required annually to protect yields of the root and seed. Our objective was to improve Alternaria leaf blight tactic by identifying effective products and application intervals using a calendar or the TOM-CAST disease forecaster. Product efficacy trials were conducted at two sites over two years and included 14 products and an untreated control. The fungicides pyraclostrobin and azoxystrobin + difenoconazole were consistently effective in limiting leaf blight compared to the untreated control. Fluxapyroxad + pyraclostrobin was also effective both years across both sites with one exception. Mancozeb, fluazinam, chlorothalonil, difenoconazole, and penthiopyrad were effective when disease pressure was not severe. Applications of pyraclostrobin or mancozeb resulted in a higher seedhead yield than the untreated control. The TOM-CAST disease forecaster, with spray thresholds of 10 or 15 disease severity values (DSVs) was tested at four field sites for each of two years and compared to fungicides applied every 7 or 10 days or not applied (untreated control). All treatments at three of the four sites limited disease severity compared to the untreated control in both years. According to the area under the disease progress curve (AUDPC) data, fungicide treatment programs in 2013 were similar and better than the untreated control. The AUDPC data from 2014 indicated that the 7-day application treatments had fewer diseased plants than the untreated control at all sites; the TOM-CAST 10 and 15 DSV treatments limited disease compared to the untreated control at three of the four sites. The TOM-CAST 10 DSV treatment yielded similarly to the 10-day treatment at one site for both fresh and dried root; the TOM-CAST 10 and 15 DSV treatment yields were similar. At a second site, fresh and dried root yields were similar for the 7-day and TOM-CAST 10 DSV treatments; 10-day and TOM-CAST 15 DSV treatments were similar. TOM-CAST 10 DSV may provide a balance between reducing fungicide applications while protecting valuable ginseng root yields.

中文翻译：

---

西洋参链格孢叶枯病的防治策略

摘要 栽培西洋参（Panax quinquifolius）是一种多年生草本植物，具有重要的中药价值。该作物在聚丙烯遮阳布下进行商业化生产，创造了有利于由 Alternaria panax 引起的叶枯病的气候；每年需要频繁使用杀菌剂，以保护根和种子的产量。我们的目标是通过使用日历或 TOM-CAST 病害预测器确定有效产品和应用间隔来改进链格孢叶枯病策略。产品功效试验在两个地点进行了两年多，包括 14 种产品和未经处理的对照。与未处理的对照相比，杀真菌剂唑菌胺酯和嘧菌酯+苯醚甲环唑在限制叶枯病方面始终有效。Fluxapyroxad + 唑菌胺酯在两个站点的两年内也都有效，只有一个例外。代森锰锌、氟啶胺、百菌清、苯醚甲环唑和吡噻菌胺在疾病压力不严重时有效。与未处理的对照相比，唑菌胺酯或代森锰锌的应用导致更高的种苗产量。TOM-CAST 疾病预测器具有 10 或 15 个疾病严重程度值 (DSV) 的喷雾阈值，每两年在四个现场地点进行测试，并与每 7 天或 10 天施用或不施用（未处理的对照）的杀菌剂进行比较。与两年未治疗的对照相比，四个位点中三个位点的所有治疗都限制了疾病严重程度。根据疾病进展曲线下面积 (AUDPC) 数据，2013 年的杀菌剂处理方案与未处理的对照相似且更好。2014 年的 AUDPC 数据表明，在所有地点，7 天施用处理的病株比未处理的对照少；与未治疗的对照相比，TOM-CAST 10 和 15 DSV 治疗在四个部位中的三个部位限制了疾病。TOM-CAST 10 DSV 处理与 10 天处理的新鲜根和干燥根相似；TOM-CAST 10 和 15 DSV 处理产量相似。在第二个地点，7 天和 TOM-CAST 10 DSV 处理的新鲜和干根产量相似；10 天和 TOM-CAST 15 DSV 治疗相似。TOM-CAST 10 DSV 可以在减少杀菌剂使用和保护有价值的人参根产量之间取得平衡。与未治疗的对照相比，TOM-CAST 10 和 15 DSV 治疗在四个部位中的三个部位限制了疾病。TOM-CAST 10 DSV 处理与 10 天处理的新鲜根和干燥根相似；TOM-CAST 10 和 15 DSV 处理产量相似。在第二个地点，7 天和 TOM-CAST 10 DSV 处理的新鲜和干根产量相似；10 天和 TOM-CAST 15 DSV 治疗相似。TOM-CAST 10 DSV 可以在减少杀菌剂使用和保护有价值的人参根产量之间取得平衡。与未治疗的对照相比，TOM-CAST 10 和 15 DSV 治疗在四个部位中的三个部位限制了疾病。TOM-CAST 10 DSV 处理与 10 天处理的新鲜根和干燥根相似；TOM-CAST 10 和 15 DSV 处理产量相似。在第二个地点，7 天和 TOM-CAST 10 DSV 处理的新鲜和干根产量相似；10 天和 TOM-CAST 15 DSV 治疗相似。TOM-CAST 10 DSV 可以在减少杀菌剂使用和保护有价值的人参根产量之间取得平衡。7 天和 TOM-CAST 10 DSV 处理的新鲜和干根产量相似；10 天和 TOM-CAST 15 DSV 治疗相似。TOM-CAST 10 DSV 可以在减少杀菌剂使用和保护有价值的人参根产量之间取得平衡。7 天和 TOM-CAST 10 DSV 处理的新鲜和干根产量相似；10 天和 TOM-CAST 15 DSV 治疗相似。TOM-CAST 10 DSV 可以在减少杀菌剂使用和保护有价值的人参根产量之间取得平衡。