Gevens A J, Nequi N, Vitoreli A, Marois J J, Wright D L, Harmon C L, Harmon P F
Department of Plant Pathology, University of Florida, Gainesville.
Department of Plant Pathology, Florida Extension Plant Disease Clinic, University of Florida, Gainesville.
Plant Dis. 2008 Oct;92(10):1472. doi: 10.1094/PDIS-92-10-1472C.
Soybean rust (SBR), caused by the obligate fungus Phakopsora pachyrhizi Syd. & P. Syd., was initially reported on soybean (Glycine max L.) in Louisiana in 2004 and has since been reported on soybean and/or kudzu (Pueraria lobata (Willd.) Ohwi) in 9 states in 2005, 15 states in 2006, and 19 states in 2007 (1). The host range of P. pachyrhizi includes plants that are all in the Fabaceae or legume family. Six plant species in the United States have been reported as hosts of P. pachyrhizi: soybean, kudzu, Florida beggarweed (Desmodium tortuosum (Sw) DC.), dry bean (Phaseolus vulgaris L.), lima bean (P. lunatus L.), and scarlet runner bean (P. coccineus L.) (4). On 17 April 2008, a rust disease was observed on a weedy legume host with red showy flowers that was growing with kudzu in an overgrown vacant lot in the understory of live oak trees (Quercus virginiana Mill.) in Citra, FL. The discovery was made during routine scouting of this Integrated Pest Management Pest Information Platform for Extension and Education (IPM PIPE) mobile sentinel plot (3). The plant was confirmed by University of Florida botanists to be Erythrina herbaceae L., commonly known as coral bean. Coral bean is native to the southeastern United States and also is planted as a perennial ornamental. A sample of leaves exhibiting rust pustules characteristic of P. pachyrhizi uredinia was collected and examined with a microscope. Brown-to-brick red, angular lesions that were 3 to 11 mm in diameter (average 6.75 mm) were observed on the undersides of the leaves of two trifoliates. Within these lesions, there were several uredinia, some exuding hyaline, echinulate urediniospores (20 × 25 μm). The visual diagnosis and the species of the rust fungus were confirmed to be P. pachyrizi by a real-time PCR protocol (2). The diagnosis on this new host was verified by a USDA, APHIS National Mycologist in Beltsville, MD. Coral bean may serve as an additional overwintering host for P. pachyrhizi in the southeast. To our knowledge, this is the first report of soybean rust caused by P. pachyrhizi on E. herbaceae. References: (1) R. S. C. Christiano and H. Scherm, Phytopathology 97:1428, 2007. (2) R. D. Frederick et al. Phytopathology 92:217, 2002. (3) S. A. Isard et al. Online publication. doi:10.1094/PHP-2006-0915-01-RV. Plant Health Progress, 2006. (4) T. L. Slaminko et al. Plant Dis. 92:767, 2008.
大豆锈病（SBR）由专性真菌大豆层锈菌（Phakopsora pachyrhizi Syd. & P. Syd.）引起，2004年首次在路易斯安那州的大豆（Glycine max L.）上被发现，此后在2005年于9个州、2006年于15个州、2007年于19个州的大豆和/或葛藤（Pueraria lobata (Willd.) Ohwi）上被发现（1）。大豆层锈菌的寄主范围包括豆科或豆科植物家族中的所有植物。在美国，已报道六种植物为大豆层锈菌的寄主：大豆、葛藤、佛罗里达山蚂蝗（Desmodium tortuosum (Sw) DC.）、菜豆（Phaseolus vulgaris L.）、利马豆（P. lunatus L.）和红花菜豆（P. coccineus L.）（4）。2008年4月17日，在佛罗里达州西特拉市活橡树（Quercus virginiana Mill.）林下一片杂草丛生的空地上，一种开红色艳丽花朵的豆科杂草寄主上观察到一种锈病，该寄主与葛藤生长在一起。这一发现是在对这个用于推广和教育活动的综合虫害管理害虫信息平台（IPM PIPE）移动监测地块进行常规巡查时发现的（3）。佛罗里达大学的植物学家确认该植物为刺桐（Erythrina herbaceae L.），俗称珊瑚豆。珊瑚豆原产于美国东南部，也作为多年生观赏植物种植。采集了带有大豆层锈菌夏孢子堆特征性锈疱的叶片样本，并在显微镜下进行检查。在两片三出复叶的叶背面观察到褐色至砖红色、直径为3至11毫米（平均6.75毫米）的角状病斑。在这些病斑内，有几个夏孢子堆，一些正在散发出透明、具刺的夏孢子（20×25微米）。通过实时荧光定量聚合酶链反应规程（2），目视诊断和锈菌种类被确认为大豆层锈菌。马里兰州贝尔茨维尔的美国农业部动植物卫生检验局国家真菌学家对这一新寄主上的诊断结果进行了核实。珊瑚豆可能是大豆层锈菌在东南部的另一种越冬寄主。据我们所知，这是关于大豆层锈菌引起的大豆锈病在刺桐上的首次报道。参考文献：（1）R. S. C. Christiano和H. Scherm，《植物病理学》97:1428，2007年。（2）R. D. Frederick等人，《植物病理学》92:217，2002年。（3）S. A. Isard等人，在线出版物。doi:10.1094/PHP - 2006 - 0915 - 01 - RV。《植物健康进展》，2006年。（4）T. L. Slaminko等人，《植物病害》92:767，2008年。
