Rinehart T A, Copes W E, Toda T, Cubeta M A
United States Department of Agriculture, Agricultural Research Service, Thad Cochran Southern Horticultural Laboratory, 810 Highway 26 West, Poplarville, MS 39470.
North Carolina State University, Department of Plant Pathology, Center for Integrated Fungal Research, 225 Partners III, Raleigh, NC 27695-7567.
Plant Dis. 2007 May;91(5):616-623. doi: 10.1094/PDIS-91-5-0616.
Web blight on containerized azalea is an annual problem for commercial nurseries during summer months in the southern United States. Losses to web blight are associated with the cost of fungicide applications, delayed marketing of diseased plants, and plant death. Two hundred and eleven isolates of binucleate Rhizoctonia were recovered from azalea leaves with web blight symptoms from two nurseries in Mississippi and Alabama over 3 years. The internal transcribed spacer region (ITS) of the ribosomal DNA (rDNA) was sequenced from all isolates to determine genetic identity. A single anastomosis group (AG) of binucleate Rhizoctonia represented 92% of the samples collected from infected leaves. Genetic data and hyphal fusion experiments confirmed that these isolates belong to AG-U, which was recently identified from root and stem infections on miniature rose in Japan. Isolates of binucleate Rhizoctonia belonging to anastomosis groups AG-R, CAG-7 (=AG-S), and AG-G were also identified in the sample in low frequency. This is the first report of the occurrence of binucleate Rhizoctonia AG-U in the United States.
在美国南部的夏季，容器栽培杜鹃上的网枯病是商业苗圃每年都会面临的问题。网枯病造成的损失与杀菌剂的使用成本、染病植株上市延迟以及植株死亡有关。在三年时间里，从密西西比州和阿拉巴马州的两个苗圃中，从出现网枯病症状的杜鹃叶片上分离出了211株双核丝核菌。对所有分离株的核糖体DNA（rDNA）的内部转录间隔区（ITS）进行测序，以确定其遗传特性。从感染叶片上采集的样本中，92%由单一的双核丝核菌融合群（AG）组成。遗传数据和菌丝融合实验证实，这些分离株属于AG-U，该融合群最近在日本从微型玫瑰的根和茎感染中被鉴定出来。在样本中还低频鉴定出了属于融合群AG-R、CAG-7（=AG-S）和AG-G的双核丝核菌分离株。这是双核丝核菌AG-U在美国发生的首次报道。
