Golf Course Management

FEB 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 02.19 superintendents often make foliar applications of nutrients to greens every seven to 14 days throughout the growing season, and previ - ous research has shown this spoon-feeding approach increases the size of an existing sil - very-thread moss infestation (10, 15). Longer moss shoots are more likely to come into con - tact with the reel and/or bedknife, producing dislodged or severed shoot apices that can be dispersed by golfers, equipment or precipita - tion. Furthermore, because genotypes from green habitats exhibited much greater shoot density, more propagules per unit area will be dislodged from silvery-thread moss colonies in putting greens. Superintendents should be cognizant of any cultural practices that are manipulating the turfgrass canopy (for example, grooming, brushing, aerifying, verticutting) because they are likely dislodging asexual propagules from established colonies. However, these practices may be important tools when attempting to control severe silvery-thread moss infestations by introducing available sites within the moss colony for the establishment of desirable turf - grasses. For example, significant decreases in silvery-thread moss cover have been reported in putting greens where hollow-tine aerifica - tion and vertislicing were used on existing severe silvery-thread moss infestations (11). Strategic implementation of chemical control strategies is recommended seven days follow - ing any of the aforementioned cultural prac- tices because this timeframe is when regrowth from dislodged asexual structures occurs (4). Lastly, superintendents struggling with silvery-thread moss infestations should con - sider changes to their cutting unit setup. A lower effective height of cut will increase the likelihood of the reel and/or bedknife contact - ing silvery-thread moss shoots, so superinten- dents should combat this by raising the height of cut, using less aggressive rollers, reducing cutting unit weight, reducing behind-center distance, and decreasing bedknife thickness. Future studies should focus on the effective - ness of these proposed management strategies on controlling silvery-thread moss cover and spread in golf course greens. Acknowledgments e authors thank the United States Golf Association for funding the research, and the many golf course superintendents who con - tributed samples of moss for this study. sidering no males were identified from greens. An alternative perspective arguing the role of spore dispersal may pose that females are bet - ter adapted to life in a putting green, while males simply do not thrive, and hence are not observed. Regardless, preventing the move - ment of spores onto golf course putting greens would be impossible because wind currents are capable of dispersing spores miles from the parent population (6). Our research suggests that dislodged shoot fragments serve as the primary dispersal mechanism. Implications for management Findings of divergent traits between golf course genotypes and native genotypes of sil - very-thread moss have important implications for management of this species. Silvery-thread moss collected from greens exhibited a much greater vertical shoot growth rate compared with genotypes from native habitats, espe - cially when cultures were supplied nutrients (Figure 4). Additionally, genotypes from green habitats had a threefold to fourfold increase in shoot density compared with genotypes from native habitats, irrespective of nutrients (Fig - ure 3). ese results have implications when at - tempting to understand and limit the inva- sion process in putting greens. For instance, % aerial rhizoid cover 90 80 70 60 50 40 30 20 10 0 Rhizoid cover (%) Nutrients Water Green Nutrients Water Native Figure 6. Percent cover occupied by aerial rhizoids as seen 50 days after the silvery-thread moss was placed into culture.

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