Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706.
Wine and Viticulture Department, California Polytechnic State University, San Luis Obispo, CA 93407.
Plant Dis. 2021 Jan;105(1):149-155. doi: 10.1094/PDIS-11-19-2290-RE. Epub 2020 Nov 16.
Potato early blight caused by and potato brown spot caused by are two common potato foliar diseases. Fungicide applications in Wisconsin target early blight with the expectation of managing brown spot simultaneously. However, distributions of the two pathogens over time and space have not been previously reported in Wisconsin. In this study, six potato fields in Wisconsin were systematically sampled during 2014 to 2017 to investigate the incidences of both pathogens; incidences of the pathogens were compared by location, timing, and year. Incidence of had been recorded starting in late June in every field every year, whereas incidence of started later in some of the fields. At the end of each growing season throughout the four years, the highest incidence (100% most of the years) of was observed in a field in Plover, located in a concentrated potato production area of central Wisconsin, and a field in Arena, located in an isolated potato production area in southern Wisconsin. The highest incidence (100% every year) of was observed in a field in Madison, an isolated potato field that was managed organically. Such distribution patterns could be a result of the different host ranges of the pathogens and abundance of inoculum in different geographic locations. In 2016, disease severity was correlated with the incidence of both pathogens ( 0.0001 to 0.0299), but in 2017, disease severity was correlated with the incidence of in most of the fields ( < 0.0001 to 0.0799). These findings suggest that both spp. are important for considering disease management strategies in central and southern Wisconsin.
早疫病由引起，褐斑病由引起，这两种是常见的马铃薯叶部病害。威斯康星州使用杀菌剂防治早疫病，同时期望能够兼治褐斑病。然而，这两种病原菌在时间和空间上的分布在威斯康星州以前尚未有过报道。本研究于 2014 年至 2017 年在威斯康星州的 6 个马铃薯田系统采样，以调查这两种病原菌的发病率；通过位置、时间和年份比较病原菌的发病率。每年，每个田块的病原菌最早于 6 月底末记录到发病，而有些田块的病原菌则发病较晚。在四年的每个生长季末，发病率最高（大部分年份为 100%）的病原菌是早疫病，出现在一个集中种植马铃薯的中威斯康星州的普洛弗（Plover）田块和一个孤立种植马铃薯的南威斯康星州的阿雷纳（Arena）田块。发病率最高（每年 100%）的病原菌是褐斑病，出现在一个孤立的、有机管理的马铃薯田块，麦迪逊（Madison）田块。这种分布模式可能是由于病原菌的不同寄主范围和不同地理位置上接种体的丰度不同所致。在 2016 年，病情严重度与两种病原菌的发病率均呈相关（ 0.0001 至 0.0299），但在 2017 年，在大多数田块中，病情严重度与早疫病的发病率呈相关（ 0.0001 至 0.0799）。这些发现表明，在中威斯康星州和南威斯康星州，这两种病原菌都对考虑病害管理策略非常重要。
