Golf Course Management

MAR 2019

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03.19 GOLF COURSE MANAGEMENT 75 Aerification treatments were applied using a Toro ProCore 648 operating at 3,000 rpm. e low-intensity surface disruption treatments were achieved by removing half of the 0.5-inch tines from the tine holders. Ejected cores were removed with a shovel, and dry sand was hand- broomed into applicable plots until holes were completely filled. Verti slice treatments were applied using a Billy Goat Power Rake that cut 0.05-inch (0.127 cm) wide slits on 2-inch (5 cm) centers at a depth of 0.3 inch (0.76 cm) in the turfgrass surface. e herbicide treatments were: 1) carfen - trazone applied at 0.1 pound a.i./acre (0.11 kg/hectare; equivalent to 6.7 fluid ounces QuickSilver/acre) at one week before and one week after cultivation treatments (that is, four applications per year); and 2) no herbi - cide. Herbicide applications were made using a two-nozzle CO 2 -powered backpack sprayer equipped with TeeJet XR8002VS nozzles, and calibrated to deliver a spray volume of 40 gal - lons/acre (374 liters/hectare). All herbicide ap- plications included a nonionic surfactant ap- plied at a 0.25% v/v. Silvery-thread moss is poikilohydric (that is, it has no mechanism to Cultivation vs. silvery-thread moss prevent desiccation) and has the potential to be in a dormant state if extracellular water is not present. erefore, 0.1 inch (0.254 cm) of irrigation was applied the night before carfen - trazone applications were made to ensure the silvery-thread moss would be actively photo - synthesizing. Percent moss cover was obtained using a 3- × 4-foot rating grid containing 330 intersec - tions on 2- × 2-inch centers. An application of carfentrazone causes rapid necrosis of the ga - metophyte tissue; however, the gametophyte carcass does not break down, and regrowth occurs several weeks later (personal observa - tions). erefore, a positive grid count was re- corded if a silvery-thread moss gametophyte was situated directly under an intersection, re - gardless of whether it was green and healthy, or black/brown and desiccated. Initial moss cover was determined for each plot on Sept. 24, 2012, one week before any treatments were applied. Subsequent ratings were recorded on March 21, 2013; Oct. 1, 2013; April 1, 2014; and Oct. 1, 2014. Moss cover in individual plots ranged from 20% to 60% at study initia - tion; therefore, percent change in moss cover 10 0 -10 -20 -30 -40 -50 13 mm hollow tine, 3.9% SD 13 mm hollow tine, 7.2% SD Vertislice Untreated Change from initial moss cover (%) Sept. 1 Sept. 1 Sept. 1 Jan. 1 Jan. 1 May 1 May 1 2012 2013 2014 a a ab ab b b b b Figure 1. Effects of cultivation treatment on silvery-thread moss cover in a creeping bentgrass putting green in 2013 and 2014. Cultivation treatments were performed each spring and fall starting on Oct. 1, 2012, and ending on April 7, 2014. Means followed by the same letter on individual rating dates are not significantly different. at subsequent rating dates was determined by comparing moss cover in each plot with its initial value. Negative values indicate moss cover decreased. Results and discussion Several treatments were effective at reduc- ing silvery-thread moss cover over the course of the two-year field study; however, no treat - ment combination completely eradicated silvery-thread moss. Originally, we hypothe - sized that cultivation would only reduce moss cover when applied in conjunction with the herbicide. However, both treatments — with cultivation alone and herbicide alone — re - duced moss cover. Cultivation Aerification and vertislicing are golf course management practices that create open spaces, or voids, in the turfgrass canopy; however, it was unknown if these voids would be colo - nized by silvery-thread moss or creeping bent- grass. Our hypothesis that cultivation would only decrease silvery-thread moss cover when combined with herbicide use or topdressing

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