Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706.
Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706.
Plant Dis. 2023 Sep;107(9):2763-2768. doi: 10.1094/PDIS-12-22-2875-RE. Epub 2023 Aug 31.
Sclerotinia stem rot (SSR) is a major disease of soybean across the Upper Midwest region of the United States. Management of this disease has relied on fungicide applications, but due to the environmental conditions necessary for SSR to develop, many of these applications are unnecessary. To mitigate this, predictive models have been developed using localized weather data for predicting the formation of apothecia, the inoculum source of SSR, and these models were integrated into a decision support system called Sporecaster. However, these models do not account for the soybean resistance levels to SSR. In this study, fungicide trials were performed across seven site-years in Wisconsin between 2020 and 2022 examining fungicide applications applied at one of three action thresholds (low, moderate, and high) following Sporecaster recommendations in combination with four soybean varieties representing three SSR resistance levels (susceptible, moderately resistant, and resistant). From these trials, the low and moderate action thresholds resulted in similarly low disease severity index (DIX) levels comparable to the standard across all varieties. However, the low action threshold was most accurate for predicting SSR development in the susceptible variety, and the high action threshold was most accurate for predicting SSR development for the three resistant varieties. Both the susceptible soybean and a moderately resistant line yielded similarly high results. Additionally, the use of all fungicide applications led to similar partial profits at grain sale prices of either $0.44 or $0.55 kg. Overall, this study uncovered relationships between soybean resistance levels to SSR and Sporecaster, allowing for improved recommendations for fungicide applications.
菌核茎腐病（SSR）是美国中西部地区大豆的主要病害。这种疾病的管理一直依赖于杀菌剂的应用，但由于 SSR 发展所需的环境条件，许多应用都是不必要的。为了减轻这种情况，已经使用局部天气数据开发了预测模型，用于预测子囊盘的形成，子囊盘是 SSR 的接种源，这些模型已集成到称为 Sporecaster 的决策支持系统中。然而，这些模型没有考虑到大豆对 SSR 的抗性水平。在这项研究中，2020 年至 2022 年在威斯康星州的七个地点进行了杀菌剂试验，共进行了七年，研究了根据 Sporecaster 建议在三种作用阈值（低、中、高）下应用杀菌剂的情况，同时结合了四种代表三种 SSR 抗性水平（敏感、中度抗性和抗性）的大豆品种。从这些试验中，低和中作用阈值导致与所有品种的标准相比，疾病严重指数（DIX）水平相似地低。然而，低作用阈值最适合预测敏感品种中 SSR 的发展，高作用阈值最适合预测三种抗性品种中 SSR 的发展。易感大豆和中度抗性品种的产量同样高。此外，以每公斤 0.44 或 0.55 美元的谷物销售价格使用所有杀菌剂应用都会产生类似的部分利润。总的来说，这项研究揭示了大豆对 SSR 和 Sporecaster 的抗性水平之间的关系，为杀菌剂的应用提供了更好的建议。
