Golf Course Management

DEC 2013

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

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cutting edge Research in progress of both sun and shade cumulatively. Average daily light integral for the experiment was 47.2±8.9 mol/ meter/day. Under 50% shade, signifcant differences in turfgrass quality occurred at one, two and six weeks after initial shading (WAIS) for Jones Dwarf, Celebration and Tifway, respectively. For 70% shade, quality differences were observed at 2 WAIS for Celebration and 4 WAIS for Tifway. All shade treatments had below acceptable turfgrass quality for at least one week. Jones Dwarf appeared more susceptible to shade at a shorter duration than Celebration and Tifway and may require changes in management under extended cloud cover. — Photo by Z. Raudenbush Nitrogen source affects silverythread moss Soluble nitrogen (N) has been observed to increase severity of silvery-thread moss (STM) in putting greens. It is unknown how differing soluble N sources applied at various spray volumes affect STM colonization. Two N sources, urea and ammonium sulfate (AMS), were applied weekly at 4.36 pounds N/acre at three spray volumes: 10, 44 and 108 gallons of water/acre. STM was grown in the greenhouse from a population collected in the feld. Digital images were taken weekly and analyzed to determine percent STM cover. At seven weeks after initial treatment (WAIT), plants were harvested, dried and weighed. Nitrogen source had a signifcant effect in both runs on every rating date, regardless of spray volume. At 7 WAIT, AMS resulted in 74% moss coverage in run 1 and 56% in run 2, which was signifcantly higher than urea (42% and 36%, respectively). Moss treated with AMS produced a threefold increase in dry matter compared to plants treated with urea in both runs of the study; the increased dry weight was the result of longer gametophyte flaments. Longer flaments allow STM to better compete for light in the turf's canopy and likely improve its ability to withstand burial from frequent topdressing — Zane Raudenbush and Steven Keeley, Ph.D. (, Kansas State University, Manhattan Shade duration affects bermudagrass Photo by J. Bryan Unruh Teresa Carson 92 GCM December 2013 Field trials were conducted to evaluate the effect of shade duration on turfgrass health in three bermudagrass cultivars: Tifway, Jones Dwarf and Celebration. Four shade intervals were implemented (no shade, weekly, biweekly, monthly) for eight weeks using 50% shade cloth for Jones Dwarf, and 50% and 70% shade cloth for Tifway and Celebration. Each treatment received four weeks Brian Glenn, and Jason Kruse, Ph.D. (, University of Florida, Gainesville, Fla.; J. Bryan Unruh, University of Florida, Jay, Fla. Bermuda cultivarsÕ response to shade This study investigated the response of fve bermudagrass cultivars (Tifway, Patriot, Celebration, TifGrand and TifSport) under four light environments: full sunlight, 30%, 60% and 90% simu- Photo by Philipe Aldahir lated shade. Grass plugs from the cultivars were collected with a standard cup cutter and planted in pots prepared with a root zone built to USGA recommendations for putting greens. When turf was fully grown and had adequate quality, pots were placed under shade tents with individual irrigation systems at the Turfgrass Research Unit in Auburn, Ala. TifGrand and Tifway were also evaluated under feld conditions under 70% shade. Turf quality and cover were decreased by shade over time. Turf quality ranking for cultivars under 60% continuous shade after 10 weeks was: TifGrand > TifSport > Celebration ≥ Tifway > Patriot. TifGrand and Celebration had the lowest turfgrass quality under full sunlight, because of excessive seedhead production. Cultivars with superior quality had the least increase in leaf etiolation. In the feld, Tifway decreased in quality after six weeks under shade; TifGrand maintained maximum quality under 70% continuous shade throughout the experiment. — Philipe C.F. Aldahir and J. Scott McElroy, Ph.D. (, Auburn University, Auburn, Ala. GCM Teresa Carson ( is GCMÕs science editor.

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