Much of the current turfgrass shade research regarding determining minimum required DLIs is focused primarily on warm-season turfgrasses. Cool-season turfgrasses are typically more shade tolerant than warm-season turfgrass species so, generally speaking, DLIs for cool-season turf- grass are lower than those for many warm-season turf- grasses. Reported DLIs for several warm-season species and cultivars are reported in Table 2. Bermudagrass, as expected, has the highest DLIs ranging from 13.9 – 18.6 mol m-2
d-1 in the spring/fall and 18.6 – 22.4 mol m-2 d-1 in
the summer. Tis was followed by Centipedegrass (13.4 – 14.7), Seashore paspalum (11.1 – 13.0), St. Augustinegrass (10.6 – 11.5), and Zoysiagrass (9.7 – 11.3). Terefore, for clients dealing with substantial shade in southern envi- ronments, zoysiagrass and St. Augustinegrass offer the highest shade tolerance (lowest DLI) and greatest likeli- hood for success. Within zoysiagrass varieties, additional research has shown that fine textured species that are often interspecific crosses of Z. japonica and Z. matrella or Z. pacifica typically have better shade tolerance than coarse textured varieties of Z. japonica.
Citations Bell, G.E., T.K. Danneberger, and M.J. Mc- Mahon. 2000. Spectral irradiance available for turfgrass growth in sun and shade. Crop Sci. 40:189–195.
Bunnell, B. T., L. B. McCarty, J. E. Faust, N. C. Rajapakse, and W. C. Bridges. 2005. Quantifying a daily light integral require- ment of a ‘TifEagle’ bermudagrass golf green. Crop Sci. 45(2): p. 569-574.
Gardner, D. S. and R. M. Goss. 2013. Man- agement of Turfgrass in Shade. P. 219-247. In. Stier et al. (ed.) Turfgrass: Biology, Use, and Management. Agron. Monogr. 56. ASA, CSSA, and SSSA. Madison, WI.
Glenn, B., J. Kruse, and J. B. Unruh. 2012. Daily light integral requirements for twelve warm-season turfgrasses. Int. Ann. Meet. p. 72111.
Korczynski, P.C., J. Logan, and J.E. Faust. Mapping Monthly Distribution of Daily Light Integrals across the Contiguous United States. HortTech. 12(1): 12-16.
Turgeon, A.J. 1995. Turfgrass Management. 4th ed. Prentice-Hall, Inc. Upper Saddle River, NJ.
Wherley, B.G., P. Skulkaew, A. Chandra, A.D. Genovesi, and M.C. Engelke. 2011. Low-input Performance of Zoysiagrass (Zoy- sia spp.) Cultivars Maintained under Dense Tree Shade. HortSci. 46(7):1033-1037.
Zhang, J., B. Gleen, J.B. Unruh, J. Kruse, K. Kenworthy, J. Erickson, D. Rowland, and L. Trenholm. 2017. Comparative performance and daily light integral requirements of warm-season turfgrasses in different seasons. Crop Sci. 57: 2273-2282.
44 Commercially Available Light Meter for determining DLI
It is important to remember that most, if not all, turfgrass species will perform best in full sun. Shade tolerance varies among species and cultivar and selecting the appropriate one for use is the first line of defense in managing healthy turfgrass in moderate to dense shade. Also, next time you see your shadow on the lawn, remember that the particles of sunlight hitting your back just traveled 93 million miles only to be obstructed from hitting your turfgrass in the last few feet thanks to you!
Casey Reynolds, PhD, is executive director of Turfgrass Producers International.
Table 1. Relative shade tolerance of turfgrasses Tolerance
Highly Shade Tolerant Shade Tolerant Shade Intolerant Highly Shade Intolerant
Cool-season species Annual bluegrass
Fine fescue Tall fescue
Roughstalk bluegrass
Kentucky bluegrass Creeping bentgrass Perennial ryegrass
Gardner and Goss, 2013. Management of Turfgrass in Shade and Turgeon, 1995.
Table 2. Reported DLI values (mol m-2 d-1) for various warm-season turfgrass species Species/Cultivar
Tifeagle bermudagrass Tifway bermudagrass
Celebration bermudagrass Tifgrand bermudagrass Tifblair centipedegrass
Seadwarf seashore paspalum Captiva St. Augustinegrass Floratam St. Augustinegrass Palisades zoysiagrass Diamond zoysiagrass Jamur zoysiagrass
1 2
data not available Data compiled from Bunnell et al. (2005) Glenn et al. (2012) and Zhang et al. (2017)
Spring/Fall n/a1
17.4 – 18.6 14.2 – 15.7 13.9 – 15.4 13.4 – 14.7 11.1 10.8 10.8
10.5 – 11.3 10.1 – 11.1 9.7
Summer 32.6
21.4 – 22.4 19.5 – 20.2 18.6 – 20.9 13.3 – 14.7 13.0 10.6 11.5
10.9 – 11.3 11.0 – 11.1 9.9
Centipedegrass Seashore paspalum St. Augustinegrass Zoysiagrass
Bermudagrass Bahiagrass
Buffalograss Carpetgrass
Warm-season species None
TPI Turf News January/February 2018
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