Neumann Brebaum S, Boland G J
Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Plant Dis. 1999 Feb;83(2):200. doi: 10.1094/PDIS.1999.83.2.200C.
Diseases of dandelion (Taraxacum officinale) were surveyed in southern Ontario from 1993 to 1997 to identify promising pathogens for biological weed control. Two new pathogens of dandelion, Phoma herbarum Westend. and Phoma exigua Desm., were recovered and characterized from small necrotic lesions on dandelion foliage. Both Phoma spp. were frequently isolated from multiple locations and during various years of the survey, indicating that they were endemic and widespread on T. officinale in southern Ontario. Pathogenicity was assessed by inoculating detached leaves or seedlings with colonized agar disks (6 mm in diameter) or spore suspensions (1 × 10 conidia per ml). Inoculated leaves and seedlings were incubated at 22°C and 48 h of continuous leaf wetness. Lesion diameters were measured 3 days post-inoculation. Isolates that gave rise to necrotic lesions were reisolated from leaves and grown in pure culture. Their growth characteristics were compared with those of the initial isolate. Spores were ellipsoid, hyaline, and 5 × 2 μm for both species. Identification of representative isolates of both species was confirmed by the Centraalbureau voor Schimmelcultures, Oosterstraat 1, 3742 SK Baarn, The Netherlands. This is the first report of these two species as pathogens of dandelion in North America (1,2). References: (1) I. L. Conners 1967. An Annotated Index of Plant Diseases in Canada. Research Branch, Canada Dept. Agric. Pub.1251. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.
1993年至1997年期间，在安大略省南部对蒲公英（药用蒲公英）病害进行了调查，以确定有潜力用于生物除草的病原体。从蒲公英叶片上的小坏死病斑中分离并鉴定出两种新的蒲公英病原体，即草本茎点霉（Phoma herbarum Westend.）和极小茎点霉（Phoma exigua Desm.）。在调查的多个地点和不同年份，均频繁分离出这两种茎点霉，表明它们在安大略省南部的药用蒲公英上呈地方性流行且分布广泛。通过用定殖的琼脂圆盘（直径6毫米）或孢子悬浮液（每毫升含1×10个分生孢子）接种离体叶片或幼苗来评估致病性。接种后的叶片和幼苗在22°C下培养，并保持48小时连续叶片湿润。接种3天后测量病斑直径。从叶片上重新分离出产生坏死病斑的分离物，并进行纯培养。将它们的生长特性与初始分离物进行比较。两种菌的孢子均为椭圆形、透明，大小为5×2微米。这两个物种的代表性分离物的鉴定由位于荷兰巴恩市奥斯特拉特街1号、邮编3742 SK的中央真菌培养中心确认。这是这两个物种作为蒲公英病原体在北美的首次报道(1,2)。参考文献：(1) I. L. Conners 1967年。《加拿大植物病害注释索引》。加拿大农业部研究处。出版物1251。(2) D. F. Farr等人1989年。《美国植物及植物产品上的真菌》。美国植物病理学会，明尼苏达州圣保罗市。
