Golf Course Management

JUN 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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68 GOLF COURSE MANAGEMENT 06.18 It has been more than two years since the article "A state of flux" was published in the August 2015 issue of GCM. e article sum - marized the "known knowns" and "known unknowns" of off-type grasses in ultradwarf bermudagrass putting greens. e off-type issue continues to be a large part of the ultradwarf bermudagrass community, but research conducted since 2015 has aimed to answer some of these "known unknowns." Some questions have been answered, and some remain. What is the issue? Off-type grasses are defined as those with different morphology and performance com - pared to the desirable turfgrass. Figure 1 il- lustrates the aesthetic and surface uniformity disruptions the presence of off-types can cause in ultradwarf putting greens. A genetic dis - tinction does not have to exist for a grass to be considered an off-type. In fact, most of the genetic research has failed to distinguish ul - tradwarf cultivars Champion, MiniVerde and TifEagle from older cultivars such as Tifgreen and Tifdwarf despite vast differences in their morphology (6). is history of ultradwarf bermudagrass cultivars is much different than that of other bermudagrasses. e majority of cultivars used on putting greens were identi - fied as off-type grasses in Tifgreen or Tifdwarf because of desirable morphological and perfor - mance differences. e root cause of the off-type issue in the Tifgreen-derived cultivar family is still one of the "known unknowns." A review article (6) has summarized the research on the genetic stability of Tifgreen and Tifdwarf, in addition to that of other hypothetical causes for off- types in ultradwarf bermudagrasses. Regard - less of the cause or origin, off-type grasses are a major problem in ultradwarf putting greens. Research was conducted at the University of Tennessee from 2014 to 2017 to attempt to an - swer some of the concerns regarding this issue. Building an off-type collection e first step of this research was to sam- Eric Reasor, Ph.D. Jim Brosnan, Ph.D. Research update on off-type grasses in ultradwarf bermudagrass putting greens More research is needed to develop effective management practices for off-type bermudagrasses, which have different morphology but are genetically similar to ultradwarf cultivars. Figure 1. A, Off-type grasses (lighter in color and noted by red circle) present in an ultra- dwarf bermudagrass putting green. B, Close-up of an off-type grass (noted by red circle) present in an ultradwarf bermudagrass putting green. Photos by Eric Reasor

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