Tennessee Turfgrass – Tyler Carr, John Sorochan, and Jim Brosnan, Dept. of Plant Sciences, University of Tennessee
Zoysiagrass is a warm-season turfgrass used on lawns and golf courses in the transition zone and southern United States. Zoysiagrasses have become popular in part because they require fewer inputs and offer enhanced cold and shade tolerance compared to bermudagrass (Cynodon spp.). On golf course fairways, tees, and roughs, two different species of zoysiagrass are most common: Zoysia japonica (e.g., ‘Meyer’, ‘El Toro’, etc.) and Z. matrella (e.g., ‘Zeon’, Zorro’, etc.) (Patton et al., 2017). Continued turfgrass breeding efforts have sparked an interest in zoysiagrass for use on putting greens.
In 1996, ‘Diamond’ (Z. matrella) was released as a fine-textured zoysiagrass with potential to be used on putting surfaces; however, research from Clemson University determined that ball roll speeds were too slow for tournament purposes (Engelke et al., 2002; Stiglbauer et al., 2009). More recently, three Z. matrella cultivars [‘Prizm’ (M60), ‘Primo’ (M85), and ‘Trinity’ (L1F)] have been released for use on putting greens in addition to ‘Lazer’ (DALZ 1308), a first-generation hybrid of Z. matrella and Z. minima (Doguet and Lehman, 2014; Doguet et al., 2016, 2017; Chandra et al., 2020). These improved zoysiagrasses were planted at the University of Tennessee (Knoxville, TN) in 2018 to study their potential for use on putting greens over multiple seasons. This article will provide a brief overview of what has been learned in that research effort. 
Nitrogen (N) Fertilizer Requirements and Green Speed
One of the major topics surrounding zoysiagrass management on putting greens is N fertilizer requirements. A 16-week study in 2020 compared the performance and quality of Prizm, Primo, Trinity, and Lazer when receiving annual N rates of 1.5 or 3 lb N 1000 ft-2 (0.19 or 0.38 lb N 1000 ft-2 every two weeks during summer) supplied as urea. All plots were mowed at a 0.115” height of cut with a walk-behind reel mower (Greensmaster Flex 2100, The Toro Company, Bloomington, MN).
Most golf course superintendents are very familiar with using a Stimpmeter to provide a measure of green speed (i.e., ball roll distance; Radko, 1980). When mowing and rolling five times weekly, green speeds for all zoysiagrasses tested averaged at least 10.5’ over the 16-week study period, even when receiving 3 lb N 1000 ft-2 (Figure 1). In general, the 3 lb N 1000 ft-2 rate resulted in superior color compared to 1.5 lb N 1000 ft-2 (Figure 2) while still maintaining green speeds greater than those historically reported for Diamond. Further testing of other annual N rates between 1.5 and 3 lb 1000 ft-2 will be needed to determine the specific amount of N required to maintain acceptable quality and optimal green speed on zoysiagrass putting greens in Tennessee. Nonetheless, the range of N rates tested in this study provides a starting point for golf course superintendents considering renovating to zoysiagrass putting surfaces.
Bermudagrass Encroachment
Aside from managing zoysiagrass for performance, golf course superintendents will likely face encroachment from another warm-season turfgrass, bermudagrass. Controlling bermudagrass in Z. japonica typically involves multiple applications of Fusilade II (fluazifop) + Turflon Ester (triclopyr) (Brosnan et al., 2011); however, the tolerance of greens-type zoysiagrass to this treatment is unknown. A two-year study was initiated in August 2020 at the University of Tennessee and the University of Arkansas to evaluate the tolerance of Prizm and Lazer zoysiagrass to several postemergence herbicides including Fusilade II (4 fl oz/A), Turflon Ester (32 fl oz/A), Fusilade II (4 fl oz/A) + Turflon Ester (32 fl oz/A), Revolver (26.2 fl oz/A), and Dismiss NXT (8 fl oz/A).
Unlike Z. japonica, both Fusilade II + Turflon Ester and Turflon Ester alone resulted in unacceptable and...