Elmore W C, Gooch M D, Stiles C M
Department of Plant Pathology, University of Florida, P.O. Box 110680, Gainesville 32611-0680. Florida Agricultural Experiment Station Journal Series Number R-08989.
Plant Dis. 2002 Dec;86(12):1405. doi: 10.1094/PDIS.2002.86.12.1405B.
Gaeumannomyces graminis var. graminis is an ectotrophic, root-infecting fungus found on some warm-season turfgrass species (1). A sample of seashore paspalum (Paspalum vaginatum) exhibiting rotted roots and stolons was taken from dying patches of turf in a home lawn in Hernando County, FL, and submitted to the Florida Extension Plant Disease Clinic, Gainesville, in October 2001. The lawn had been established within the previous year. Strongly lobed hyphopodia typical of G. graminis var. graminis (3,4) were present on diseased roots and stolons, and no other fungal plant pathogens were detected in the sample. Diseased roots and stolons with lobed hyphopodia were surface-sterilized and placed on one-quarter-strength potato dextrose agar (PDA) amended with rifampicin and streptomycin. One isolate produced structures characteristic of G. graminis var. graminis (3,4), including dark, strongly lobed hyphopodia, and perithecia and ascospores in PDA after incubation. The isolate (PDC 2965) was grown on a sterile ryegrass seed substrate at 25°C for 4 weeks to produce inoculum (2). The isolate was used to inoculate pots of 'Sea Isle 1' seashore paspalum grown in sterile soil from sprigs. An inoculum layer, 1 to 2 cm deep, was placed 2 to 4 cm below each sprig and covered with an overlay of sterile soil prior to sprigging (2). Following 4 weeks of plant growth in a greenhouse, dark, necrotic lesions appeared on leaf bases. Very dark lesions developed on roots, and brown runner hyphae and strongly lobed hyphopodia were observed on root and shoot tissues. Selected pieces of symptomatic root and shoot tissue were surface-sterilized and placed on PDA. One week later, dark mycelia and deeply lobed hyphopodia were observed growing from roots and shoots on the PDA. After 1 month, black, flask-shaped perithecia, 156 to 234 μm in body width, developed in cultures. Hyaline, filiform, septate ascospores ranged from 75 to 100 μm (mean = 89 μm; n = 250) long and were approximately 2.5 μm wide. Hyphopodia, perithecia, and ascospores were characteristic of G. graminis var. graminis (3,4). To our knowledge, this is the first report of take-all root rot disease due to G. graminis var. graminis on seashore paspalum in the United States. References: (1) L. E. Datnoff et al. Plant Dis. 81:1127, 1997. (2) M. L. Elliott. Plant Dis. 79:699, 1995. (3) M. L. Elliott and P. J. Landschoot. Plant Dis. 75:238, 1991. (4) P. J. Landschoot. Taxonomy and biology of ectotrophic root-infecting fungi associated with patch diseases of turfgrasses. Pages 41-71 in: Turfgrass Patch Diseases. B. B. Clarke and A. B. Gould, eds. American Phytopathological Society, St. Paul, MN, 1997.
禾顶囊壳小麦变种是一种外生、侵染根部的真菌，存在于一些暖季型草坪草品种上（1）。2001年10月，从佛罗里达州赫尔南多县一个家庭草坪上濒死的草皮斑块中采集了一份海滨雀稗（Paspalum vaginatum）样本，该样本表现出根部和匍匐茎腐烂，并提交给了位于盖恩斯维尔的佛罗里达大学推广植物病害诊所。这块草坪是前一年铺设的。在患病的根部和匍匐茎上存在典型的禾顶囊壳小麦变种的强烈分叶状附着胞（3,4），且样本中未检测到其他真菌性植物病原体。将带有分叶状附着胞的患病根部和匍匐茎进行表面消毒，然后放置在添加了利福平和平霉素的四分之一强度马铃薯葡萄糖琼脂（PDA）上。一个分离株产生了禾顶囊壳小麦变种的特征性结构（3,4），包括深色、强烈分叶状的附着胞，以及在PDA上培养后产生的子囊壳和子囊孢子。该分离株（PDC 2965）在25°C下于无菌黑麦草种子基质上培养4周以产生接种物（2）。该分离株用于接种由嫩枝在无菌土壤中生长的“海岛1号”海滨雀稗盆栽。在每个嫩枝下方2至4厘米处放置一层1至2厘米深的接种物层，在嫩枝扦插前用无菌土壤覆盖（2）。在温室中植物生长4周后，叶基部出现深色坏死病斑。根部出现非常深色的病斑，并且在根和地上组织上观察到褐色的匍匐菌丝和强烈分叶状的附着胞。选取有症状的根和地上组织的部分进行表面消毒，然后放置在PDA上。一周后，观察到从根和地上组织在PDA上长出深色菌丝体和深深分叶状的附着胞。1个月后，在培养物中形成了黑色、烧瓶状的子囊壳，其主体宽度为156至234微米。透明、丝状、有隔膜的子囊孢子长75至100微米（平均 = 89微米；n = 250），宽约2.5微米。附着胞、子囊壳和子囊孢子是禾顶囊壳小麦变种的特征（3,4）。据我们所知，这是美国关于禾顶囊壳小麦变种引起的全蚀根腐病在海滨雀稗上的首次报道。参考文献：（1）L. E. Datnoff等人，《植物病害》81:1127，1997年。（2）M. L. Elliott，《植物病害》79:699，1995年。（3）M. L. Elliott和P. J. Landschoot，《植物病害》75:238，1991年。（4）P. J. Landschoot，与草坪草斑块病害相关的外生侵染根部真菌的分类学和生物学。载于：《草坪草斑块病害》，B. B. Clarke和A. B. Gould编，美国植物病理学会，明尼苏达州圣保罗，1997年，第41 - 71页。
