Golf Course Management

MAR 2018

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

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03.18 GOLF COURSE MANAGEMENT 73 CUTTING EDGE Teresa Carson This research project was funded in part by a grant to GCSAA from the Environmental Institute for Golf. Mapping spring dead spot using drones Spring dead spot (SDS) (caused by Op iosp erella species) is among the most destructive diseases of bermudagrass in colder regions of adaptation. Although SDS has an irregular distribution, the disease frequently recurs in the same locations from year to year. O ios aerella species infect bermudagrass in fall and predispose the warm-season turfgrass to isolated patches of winterkill. Symptoms appear in spring and can persist for months. While fungicide treatments have proved most effective in fall, symptoms are no longer present to guide application. A common suppression tactic has been to apply two or three blanket fungicide applications across the entire managed acreage in fall. Because of the large area involved, turfgrass managers have opted for more affordable fungicides, producing sporadic results. Site- specific applications based on historical disease incidence may provide the option of using more effective fungicides, but emerging technologies such as unmanned aerial vehicles (UAVs), or "drones," present opportunities for rapid mapping of diseases over large areas. This research aims to develop effective methods to map, evaluate and quantify SDS epidemics. We are also comparing site-specific fungicide applications (based on historical disease incidence) with blanket applications. Initial results are encouraging, but more data will be necessary for validation. Fungicide reduction averaged 51% in 2016 and 65% in 2017. Initial disease suppression data showed that site-specific applications of penthiopyrad were statistically equivalent to full-coverage applications. This research demonstrates how treated fungicide acreage can be reduced using site-specific management from SDS distribution maps. — Jordan C. Booth, CGCS, and David McCall, Ph.D. (dsmccall@vt.edu), Virginia Tech, Blacksburg, Va. This research project was funded in part by the United States Golf Association. Winter overseeding of bermudagrass and effects on bermudagrass health Bermudagrass is the warm-season grass of choice for golf course fairways and tees across much of the South and in the transition zone. Because bermudagrass turns straw-brown during dormancy, many turf managers often overseed with ryegrass to provide winter green color. Although a lot is known about winter- overseeded bermudagrass turf management, several questions remain. Is there any positive or negative physiological effect on bermu - dagrass winter survival? Why is poor stand density common when the overseeded spe - cies is removed? A multistate field study was conducted at four locations: Blacksburg, Va.; Fayetteville, Ark.; Lexington, Ky.; and West Lafayette, Ind. Bermudagrass was overseeded with a ryegrass blend at three rates (0, 650, 1300 pounds/acre; 0, 735, 1470 kilograms/ hectare); surface soil temperature was taken via logging temperature probes buried at the crown/soil surface level; carbohydrate con - tent of rhizome/stolon tissue was measured at predetermined sampling dates; and visual ob - servations of quality and green coverage were made. Soil temperatures were quite variable, and slight increases (1-1.5 F; +0.5 C) were oc - casionally measured in the overseeded plots compared with the non-overseeded at some sites (for example, Lexington and Fayette - ville). Physiologically, total carbohydrates and starches (long-chained sugars) declined with time, regardless of overseeding at the most northern site (West Lafayette), and, at most sites, bermudagrass spring density was poor in overseeded turf (see photo). These studies reaffirm the potential negative effects of win - ter overseeding on bermudagrass. Given that overseeding will continue to be used to pro - vide winter color and playability, best man- agement practices to maximize bermudagrass health need additional study. — Cale Bigelow, Ph.D. (cbigelow@purdue.edu), Purdue University, West Lafayette, Ind.; Gregg Munshaw, Ph.D., Uni - versity of Kentucky, Lexington, Ky.; Mike Rich- ardson, University of Arkansas, Fayetteville, Ark.; Xunzhong Zhang, Ph.D., and Mike Goatley, Ph.D., Virginia Tech, Blacksburg, Va.; and Kevin Jackson, Purdue University, West Lafayette, Ind. Teresa Carson (tcarson@gcsaa.org) is GCM's science editor. Photo by Gregg Munshaw Photo by Jordan Booth

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