Golf Course Management

NOV 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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11.18 GOLF COURSE MANAGEMENT 65 Prolonged ice cover causes another type of low-temperature kill. Ice cover on putting greens during the winter of 2013-2014 caused extensive winterkill throughout the Great Lakes region of the United States (4). e primary cause of winterkill from ice sheets is from toxic gas accumulation or oxygen deple - tion resulting in anaerobic conditions (14). Ice cover and crown hydration are the two pri - mary causes of annual bluegrass death over the winter. Re-establishment after winterkill Winterkill has no defined pattern; damage may be sporadic or complete, making re-es - tablishment difficult. Re-establishing follow- ing winterkill can also be challenging because of cool spring temperatures and the demand for spring golf that results in traffic on winter - kill areas (13). If creeping bentgrass (Agrostis stolonifera L.) is killed, seeding or sodding are viable options for re-establishment. However, if annual bluegrass is killed, commercially available annual bluegrass seed is limited to one cultivar, DW-184 (1), and annual blue - grass sod is not readily available in most lo- cations. Some golf courses maintain annual bluegrass nurseries for sodding if their annual bluegrass is killed. When an annual bluegrass nursery is not available or not large enough to repair all the damage, creeping bentgrass is commonly seeded into damaged areas. Golf course su - perintendents have also experimented with collecting clippings containing annual blue - grass florets (commonly called seed) from an- nual bluegrass putting greens and spreading them on dead areas to re-establish annual bluegrass (7). Annual bluegrass is unique in that seeds can ripen on panicles severed from the mother plant on the same day that pollination occurs (5). Annual bluegrass seed germinates over a temperature range of 40 F to 70 F (4.5 C- 21 C) (3), and annual bluegrass germina- tion has been reported in the fall and spring, and to a lesser extent throughout the entire growing season, in Michigan (2). Re-estab - lishment in the spring when temperatures are below optimum for creeping bentgrass ger - mination is difficult (13) because the optimal air temperature range for creeping bentgrass germination is 59 F to 86 F (15 C-30 C), with a soil temperature of 59 F to 77 F (15 C-25 C) (15). Many different cover systems have been used to raise canopy and soil temperatures to hasten establishment, including permeable geotextile, clear polyethylene, and cotton grow covers (6, 8, 10, 16). We conducted research to determine the effects of fertilizer program, protective cover, and seeding creeping bentgrass or annual bluegrass on putting green re-establishment following simulated winterkill. Materials and methods Research was conducted in 2007 and 2008 at the Hancock Turfgrass Research Center (HTRC) at Michigan State University. To simulate winterkill, a creeping bentgrass put - ting green was sprayed with glyphosate several times before seeding to ensure complete kill of the existing turf stand. e putting green was prepared for seeding using the Miltona Turf Tools Jobsaver aerator attachment on a Jacob - sen GA-30 aerator. e Jobsaver attachment creates cone-shaped depressions in the putting green to enhance seed establishment. Seeding Penn A-4, Providence and Alpha creep - ing bentgrass were seeded at 2 pounds/1,000 square feet (10 grams/square meter). Annual bluegrass florets were collected from an annual bluegrass putting green at the HTRC by mow - ing at a height of 0.16 inch (4 mm) on April 17, 2007, and April 28, 2008. e clipping-floret mixture was applied at 2 pounds/1,000 square feet to each plot receiving the annual bluegrass seeding treatment. e creeping bentgrass cul - tivars were seeded on April 21, 2007, and May 2, 2008, and the annual bluegrass clipping- floret mixture was applied to the plots on May 4, 2007, and May 9, 2008. e delay in apply - ing the clipping-floret mixture was due to tim- ing of annual bluegrass floret production in the annual bluegrass green at the HTRC. Im - mediately following seeding, sand topdressing was applied at 115 pounds/1,000 square feet (562 grams/square meter), and starter fertilizer (19N-25P-5K) was applied at 1 pound nitro - gen/1,000 square feet (5 grams/square meter), followed by 0.5 inch (12 mm) of irrigation. Cover treatments Creeping bentgrass seedling emergence was on May 10, 2007, and May 14, 2008. Cover treatments (a clear polyethylene cover or a non-covered control) were initiated upon creeping bentgrass seedling emergence. Plots were covered when nighttime temperatures were forecast below 50 F (10 C). Covers were applied in the late evening, with approximately two hours of sunlight remaining. e covers were removed for the day by approximately 8 a.m. the following morning in order to sim- ulate golf course putting greens that were kept open for play during re-establishment. Fertilization programs Fertilization programs were also initiated upon creeping bentgrass seedling emergence. For the purposes of this study, a creeping bentgrass green was sprayed several times with glyphosate in order to simulate winterkill.

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