Golf Course Management

MAR 2014

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80 GOLF COURSE MANAGEMENT 03.14 Dollar spot lesions on tufted bulrush (Trichophorum cespitosum) on the seashore near Peggys Cove, Nova Scotia, Canada. Photos by T. Hsiang specimens were deposited in the WSU My- cological Herbarium as WSP 72345 to WSP 72348. This is the frst report of U. cynodontis causing smut on bermudagrass in Washing - ton state and represents the northernmost re- cord of this fungus in North America. The occurrence of U. cynodontis in Washington suggests that the pathogen may exist in other hot and dry areas of northwestern North America where bermudagrass can be associ - ated with recreational, landscape or natural settings. Source: Plant Disease, February 2014, 98(2):280. http://dx.doi.org/10.1094/PDIS-05-13-0560-PDN J.K.S. Dung, Ph.D. (Jeremiah.Dung@oregonstate.edu), is an assistant professor in the department of botany and plant pathology, Central Oregon Agricultural Research Center, Oregon State University, Madras, Ore.; L.M. Car - ris, Ph.D., is an associate professor in the department of plant pathology, Washington State University, Pullman, Wash.; and P.B. Hamm is station director and professor emeritus in the department of botany and plant pathology, Hermiston Agricultural Research and Extension Center, Oregon State University, Hermiston, Ore. (Report) Dollar spot disease on the oceanside sedge Trichophorum cespitosum Sclerotinia omoeocarpa is a fungal patho- gen that causes dollar spot disease on more than 40 plant species, mostly in the family Poaceae, and is considered the most wide - spread pathogen of golf course turfgrasses in the St. Lawrence River region. In June 2011, lesions were observed on tufted bulrush, Tric o orum cespitosum (Poales, Cyperaceae), on the seashore near Peggys Cove, Nova Scotia, Canada. Single bunches had up to 40% of the leaves affected. The foliar symptoms were large hourglass- shaped lesions, up to 2 inches (5 centimeters) long, with a straw-colored portion capped at two ends by dark zone lines on surrounding green foliar tissue. These lesions were simi - lar to dollar spot lesions found on turfgrasses such as Kentucky bluegrass (Poa pratensis). A fungus was isolated from symptomatic leaf segments and, after three days of growth on nutrient agar at room temperature, white fuffy mycelia covered the entire petri dish. Brown columnar structures began to form in the colony centers after seven days with abundant aerial growth, and cultures became cinnamon-colored after 14 days. Dark brown or black substratal stroma were formed on or in the agar, and cultures appeared dark brown from the bottom. DNA was extracted and amplifed using ribosomal DNA primers ITS1 and ITS4, and the DNA fragment sequenced (GenBank Accession No. KF447776). The sequence showed a top match of 522/524 bp identity with the ITS sequence of an isolate of S o - moeocarpa, with the next 40 top matches also identifed as S. omoeocarpa. This was an un - expected fnding, so attempts were made to test the ability of this isolate to cause disease on turfgrasses. Two-week-old seedlings of Penncross creeping bentgrass (Agrostis stolonifera), Touchdown Kentucky bluegrass (Poa praten - sis) and Express perennial ryegrass (Lolium perenne) were inoculated by placing 0.2- inch (5-millimeter) diameter mycelial plugs from fve-day-old cultures onto the leaves of plants grown in small containers, and in - cubating under enclosed humid conditions throughout the test. White aerial hyphae on the leaves and straw-colored leaf lesions were observed by seven days after inoculation on Kentucky bluegrass and perennial ryegrass, but no lesions or hyphal growth were ob - served on creeping bentgrass. No signs or symptoms were observed on leaves where sterile agar plugs were used as inoculum. These tests were repeated three times with the same results, and a positive control was included by using an S. omoeocarpa isolate known to be pathogenic to creeping bent - grass under the same test conditions. Disease was observed on creeping bentgrass with the control isolate but never with the isolate from T. cespitosum. Sclerotini omoeocarpa was re- isolated from the lesions on Kentucky blue - grass and perennial ryegrass to satisfy Koch's postulates. To the best of our knowledge, this is the frst report of S. omoeocarpa on T. cespitosum worldwide, involving an isolate that was found to cause disease on Kentucky bluegrass and perennial ryegrass, but was not pathogenic to creeping bentgrass in vitro. 078-095_March14_TechwellCuttingEdge.indd 80 2/18/14 1:46 PM

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