Golf Course Management

FEB 2019

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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72 GOLF COURSE MANAGEMENT 02.19 Zane Raudenbush, Ph.D. Lloyd R. Stark, Ph.D. Differing genetic traits in silvery-thread moss on greens and in native habitats Silvery-thread moss in putting greens appears to be uniquely adapted to the golf course environment, and management practices likely contribute to its success. Silvery-thread moss (Bryum argenteum Hedw.) is the most pervasive moss species on putting greens in the United States. Several chemical and cultural control strategies have attempted to eradicate this species in putting greens with limited success (9). Interestingly, putting greens present an altered microhabitat that is ideal for silvery-thread moss, a special - ist that requires disturbance to survive. On greens, this disturbance is provided through daily mowing, aeration, brushing, groom - ing, foot traffic and irrigation. Additionally, silvery-thread moss is tolerant of desiccation (8), which allows it to survive prolonged peri - ods without water. Silvery-thread moss is also capable of producing prodigious amounts of buoyant, specialized asexual propagules called bulbils (14), and fragmentation of its shoots only serves to propagate populations because the entire plant body is capable of regenerat - ing new plants (2). Both bulbils and shoot fragments produce an extensive network of rhizoids, which effectively anchor these struc - tures in the thatch layer of putting greens (Fig- ure 1). us, it is no surprise that this moss has proved to be a formidable weed species for superintendents. An infestation of silvery-thread moss typi - cally begins as a small, circular colony (<5 cen- timeters in diameter). If this colony is not me- chanically removed with a knife or cup cutter, then it will continue to persist in the putting green either as new colonies establishing close to the original colony, forming pure patches (Figure 2, top), or interwoven within the grass canopy, that is, not exhibiting discrete patch- forming behavior (Figure 2, bottom). Superin - tendents typically use chemical control strat- egies to keep silvery-thread moss populations in check. Most often a product containing the active ingredient carfentrazone-ethyl is applied, which inhibits chlorophyll synthesis and ultimately results in destruction of cel - lular membranes (13). Unfortunately, a single application of this contact herbicide merely in - jures the shoot tissue, and new shoot growth is typically observed two to three weeks after application (9). Many superintendents have observed reductions in populations using fo - liar applications of zinc-containing products, ferrous sulfate and copper sulfate, with the literature revealing mixed results. Overall, most researchers reported about 30%-50% silvery-thread moss control using three to four repeated applications of the aforementioned products (9). e ability to develop a successful control This research was supported in part by funding from the United States Golf Association. Figure 1. Silvery-thread moss shoots produce rhizoids that anchor the moss in the thatch layer of a putting green. Photo by Lloyd Stark

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