Golf Course Management

MAR 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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76 GOLF COURSE MANAGEMENT 03.19 turned out to be incorrect; both vertislicing and 3.9% surface disruption aerification re - duced silvery-thread moss cover compared with the untreated control by the end of the study (Figure 1). Established silvery-thread moss colonies produce a dense mat of shoots and rhizoids that deter recolonization from creeping bent - grass stolons (personal observation); however, cultivation temporarily introduces available sites within the silvery-thread moss gameto - phyte. At the conclusion of year one, many of the available sites created by cultivation treat - ments were occupied by creeping bentgrass, but the effect of cultivation was not signifi - cant until the second year, after the treatments had been administered three times. Although the 3.9% surface disruption aerification and vertislicing treatments reduced silvery-thread moss cover by the spring and fall of 2014 com - pared with the untreated plots, the 7.2% sur- face disruption aerification treatment resulted in slightly less silvery-thread moss cover, but was not different from the untreated plots. Currently, it is unclear why the 7.2% surface disruption treatment was not as effective as other cultivation treatments. Further research is needed to determine whether an optimal percentage of surface disruption exists for sil - very-thread moss control. Herbicide Carfentrazone-ethyl reduced silvery-thread moss cover at every rating date throughout the study. Averaged across cultivation and topdressing treatments, a 20% reduction in silvery-thread moss cover was observed after two applications of carfentrazone at a rate of 0.1 pound a.i./acre (Figure 2). Others have reported a 39% reduction (4) and a 36% re - duction (1) in silvery-thread moss severity. No negative effects on bentgrass color or quality were observed following the split applications of carfentrazone; however, this herbicide, a protoporphyrinogen oxidase inhibitor (14), caused rapid necrosis in the gametophore tips by two to three days after treatment. A total of eight applications of carfentrazone were ap - plied throughout the duration of the study, but on average, only an 80% reduction in moss severity was observed. Bryophytes, such as silvery-thread moss, have been reported to have a slower decom - position rate compared with vascular plants. Carfentrazone is very effective at injuring Carfentrazone vs. silvery-thread moss 60 40 20 0 -20 -40 -60 -80 -100 Herbicide Untreated Change from initial moss cover (%) Sept. 1 Sept. 1 Sept. 1 Jan. 1 Jan. 1 May 1 May 1 Jan. 1 2012 2013 2014 2015 a b a b a b a b Figure 2. The effect of carfentrazone on silvery-thread moss cover in a creeping bentgrass putting green in 2013 and 2014. Split herbicide applications began on Sept. 25, 2012, and the last application was on April 25, 2014. Means fol - lowed by the same letter on individual rating dates are not significantly different. Hollow-tine aerification introduces temporary holes that may permit the introduction of creeping bentgrass into a silvery- thread moss colony, as seen here.

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