North Carolina Turfgrass – Tom Samples and John Sorochan, University of Tennessee, Department of Plant Sciences
Zoysiagrass, one of the earliest grass species to be used as turf, is native to Australia, China, Japan, Korea, New Zealand and the Philippines where the weather varies greatly depending on season. This relatively slow-growing, sod-forming and warm-season species forms a durable, uniform turf in full sun and light, open shade. Many zoysiagrass varieties produce no viable seeds and must be established from sod, plugs or sprigs. Depending on the planting date, sprigging rate, and plug diameter and spacing, the vegetatively propagated varieties often require more than a year to totally cover the soil surface. Leaves and stems developing from nodes on stolons and rhizomes usually grow upright at an angle of about 90 degrees, a trait contributing to very good to excellent stand density. Zoysiagrass leaves are often stiff and stems are very tough due to high levels of lignin and hemicellulose. These attributes result in excellent wear tolerance.
The slow rate of growth of lateral stems compared to that of bermudagrass and St. Augustinegrass causes zoysiagrass turfs to take longer to recover from damage from traffic, disease or insect activity. Generally, zoysiagrasses have very good drought, heat and salinity tolerance. The nitrogen (N) requirement of the species is usually lower than that of bermudagrass. In TN, an annual N rate of no more than 2 lbs. of N per 1,000 sq. ft. per yr. is most often recommended in residential turfs maintained at a cutting height of 1½ inches or higher. Plants often do produce substantial amounts of thatch, and intensely managed and highly fertile zoysiagrass turfs may require dethatching every two or three years.
Insect pests of zoysiagrass include white grubs (larvae of several species of Scarab beetles), fall armyworm (Spodoptera frugiperda) and hunting billbug (Sphenophorus venatus vestitus). The disease large patch (Rhizoctonia solani), commonly referred to as Zoysia patch may also be problematic. Bermudagrass (Cynodon spp.) is a common weed problem in zoysiagrass turfs. Perennial weeds with fleshy, subsurface and energy-rich bulbs such as wild garlic (Allium vineale), yellow nutsedge (Cyperus esculentus) and green kyllinga (Kyllinga brevifolia) can also compete with zoysiagrass for water, nutrients, light and space and may periodically require herbicide treatment.
An appropriate preemergence herbicide can be applied in late summer or early fall to control winter annual weeds such as annual bluegrass (Poa annua), common chickweed (Stelaria media), purple deadnettle (Lamium purpureum) and henbit (Lamium amplexicaule). Similarly, the emergence of seedlings of many summer annual and perennial weedy grasses and broadleaf weeds can be prevented by applying an appropriate preemergence herbicide in late winter or early spring. In addition to insect and disease resistance, the growth rate, low-temperature hardiness, leaf width, color and shade tolerance also vary among species and varieties.
Zoysiagrass, named in honor of the 18th century Australian botanist Karl von Zois, was introduced into the U. S. from East Asia and the Pacific Islands. It has been previously reported that, in the mid-1890’s, Z. japonica, sometimes called Japanese or Korean lawn grass, was introduced into the U. S. from the Manchurian Province of China.
Zoysia matrella was believed to have been introduced into the U.S. from the Philippine Islands in 1912 by the United States Department of Agriculture (USDA) botanist, C. V. Piper. As a result, this species is occasionally referred to as Manilagrass. Recent research regarding the history of zoysiagrass suggests that Z. matrella may actually have been introduced into the U. S. from Japan in 1892, and that Z. japonica was introduced into the U.S. from Korea in 1894.
A third species, Korean velvet grass or Mascarene grass, was most likely introduced into the U. S. from the Mascarene Islands (which are located in the Indian Ocean east of Madagascar) or from a plant collection (listed as plant introduction 9299) of USDA explorer David Fairchild in 1902 from Yokohama, Japan. Originally referred to as Z. tenuifolia, this very fine textured species is now recognized as Z. pacifica. Rankings of low-temperature hardiness, leaf width and rate of growth by species are: Z. japonica > Z. matrella > Z. pacifica.
Vegetative, Clonal Types. Improved, vegetatively established varieties marketed in Tennessee include ‘Cavalier’, ‘Diamond’, ‘El Toro’, ‘Geo’, ‘Meyer’, ‘Palisades’, ‘Royal’, ‘Zeon’ and ‘Zorro’. El Toro, Meyer and Palisades are medium-coarse, low-temperature-hardy varieties. Meyer, released in 1951, is one of the oldest varieties in the marketplace and remains the most widely maintained zoysiagrass in the state.
El Toro, released in 1986, resembles Meyer. However, El Toro is more shade tolerant, faster growing, has slightly wider leaves, is less dense and produces less thatch. In 1996, Texas A&M University released Palisades, a variety noted for good winter hardiness and improved shade tolerance. Cavalier, Royal, Zeon and Zorro are dense, fine-textured and relatively low-growing varieties. Cavalier, released for production in 1996, has long and slender leaves, good salt and traffic tolerance, and like Palisades, improved shade tolerance. Cavalier is also resistant to fall armyworms and large patch.
Royal, a variety released by Texas A&M University in 2001, has dense rhizomes and tillers, excellent salt tolerance, good shade tolerance and recovers more rapidly from injury than several other varieties. Royal may also transition from winter dormancy earlier than other varieties. Zeon, released in 1996 by Bladerunner Farms, is very tolerant of extended periods of drought, is adapted to both clayey and sandy soils, and develops a dense turf at a cutting height of ½ inch, one reason the variety is being maintained on golf course fairways. Zeon has good insect resistance, including hunting billbug, and shade tolerance.
Although the variety Zorro, released by Texas A&M University in 2001, has limited cold hardiness, it is fairly tolerant of low light conditions, recovers fairly quickly from damage, has excellent salt tolerance, and resists several diseases and insect pests. The variety Emerald, released in 1955 by the USDA, is a hybrid between Z. japonica and Z. pacifica. An objective of crossing the two species was to combine the darker green color, fine texture and excellent stand density of the Z. pacifica parent from Guam with the cold hardiness and more rapid growth rate of the Z. japonica parent from Korea. Although less tolerant of extreme low temperatures, Emerald is denser, finer textured and more shade tolerant than Meyer.
The variety ‘Innovation’, a cross between the Z. matrella variety Cavalier and an ecotype of Z. japonica named ‘Anderson 1’, a derivative of Chinese Common, is a joint release by Texas A&M University and Kansas State University. Cold tolerance, fall color retention and spring transition of the variety are equivalent to Meyer, and plants have a finer leaf texture and are more resistant to bluegrass billbug (Sphenophorus parvulus). Newer vegetatively established zoysiagrass varieties continue to gain acceptance and market-share in TN and other states located in the turfgrass ‘transition’ zone, and will most likely eventually replace both Meyer and Emerald.
Seeded Types. The inflorescence of seed-producing Z. japonica plants consist of a flower stalk called a peduncle supporting the entire inflorescence to which racemes with 10 to 50 seed-containing spikelets are attached. Each seed is suspended on a short (1½ to 6 mm) pedicel and alternately attached along each spikelet. Presently, seed of ‘Chinese Common’ Z. japonica imported from China, Japan and/or Korea is marketed in the Southeastern U.S. The color and leaf blade width of ‘Zenith’, a seed-producing Z. japonica variety released in 2000 by Patten Seed Company resemble Meyer.
‘Compadre’ (formerly named ‘Companion’) is another Z. japonica variety that yields viable seeds. It also resembles Meyer, and may transition from winter dormancy slightly earlier than Zenith. Chinese Common, Compadre and Zenith are not intended to be maintained in moderate to heavy shade. Zoysiagrass seeds are often pre-treated (primed) and may be coated before packaging in an effort to improve the uniformity of seed germination and seedling growth, respectively. There are approximately 601,440 zoysiagrass seeds per pound.
Classification of Species/Varieties
Historically, and based on morphological characteristics such as leaf blade width and inflorescence as well as traits including the level of shade tolerance, individual varieties have been categorized as being japonica, matrella or pacifica species or “types” within the genus Zoysia.
Recently, genetic research conducted at North Carolina State University in collaboration with the University of Florida, the USDA- Agricultural Research Service in Tifton, GA and Blue Moon Farms, LLC revealed that an “inter-connectedness” exists among species. Because zoysiagrasses are cross fertile, plant breeders are able to develop improved varieties with traits of keen interest from each species as well as valued and overlapping traits that both species share. A total of 62 varieties and collections from five different zoysiagrass species (Z. japonica, Z. matrella, Z. machrostachya, Z. minima and Z. sinica) were included in this study.
DNA markers were used to investigate the genetic makeup of each of the 62 zoysiagrass samples which fell into one of three categories identified by the researchers as Clusters. Cluster I included true Z. japonica varieties and Cluster III, true Z. matrella varieties, while Cluster II consisted of hybrids between the two species. Cluster II was divided into two subgroups. The researchers labelled the subgroups Hybrid I and Hybrid II. Hybrid I contained Z. japonica x Z. matrella hybrids with a higher concentration of genetic material from Z. japonica. Hybrid II contained Z. japonica x Z. matrella hybrids with a higher concentration of genetic material from Z. matrella. In addition to benefiting turfgrass breeders, this new information should help turfgrass industry professionals develop effective zoysiagrass sod production and turf management plans according to variety-specific requirements.
Interest in breeding, producing and marketing zoysiagrasses for use on golf greens is growing. Presently, Diamond, a variety of Z. matrella with fine to dwarf leaf texture, resistance to large patch and fall armyworm, and excellent stand density released by Texas A&M University in 1996, is being maintained on a number of golf greens in the U. S. Breeders and researchers are developing and evaluating new zoysiagrasses (e.g., ‘Primo’, ‘Prizm’, ‘DALZ1308’ and ‘Trinity’) for suitability as ‘sustainable’ putting surfaces.
In 2011, Prizm was identified as a distinctly different vegetative patch or clonal plant with fine leaf texture and a deeper green color compared to other plants growing under cultivated conditions near Proteet, TX and originating from crosses among Zeon, Trinity, and two unpatented plants ’29-2 B9’ and ‘380-1’. DALZ1308, a new and yet to be named ultra-dwarf zoysiagrass developed at Texas A&M University specifically for putting greens is a hybrid between Z. minima and Z. matrella with very fine leaf texture, high aerial shoot density and improved winter color retention. The species Z. minima is native to New Zealand where it grows along the coast to ~ 2000 ft. above sea level on sand dunes and in sandy and gravelly soils.
National Turfgrass Evaluation Program (NTEP). The results of the NTEP Zoysiagrass Tests can help determine if a particular variety of interest is well adapted to a local area or region and a specific level of maintenance. There have been a total of five NTEP Zoysiagrass Tests. The first test or trial initiated in 1991 contained 21 entries of which four were seeded. Entries were evaluated from 1992 to 1995 by university researchers at 21 locations (AL, AR, AZ, CA- 4 sites, FL- 2 sites, GA- 2 sites), ID, IL- 2 sites, Kansas- 2 sites, KY, MD- 3 sites, MD, MS, MO, NE, OH, OK, TX- 3 sites and VA) throughout the U. S.
Evaluators used standard procedures and formats to determine such traits as overall quality, color, leaf texture, spring transition, establishment/seedling vigor, drought tolerance, frost tolerance/winter kill, and both insect and disease resistance. The 2013 National Zoysiagrass Test is currently underway. Thirty-five named and experimental varieties are being evaluated in AL, AR, AK, CA, FL- 2 sites, GA, IN, KS, MO, NC- 2 sites, TN and TX- 2 sites. Progress reports for 2014 – 16 have been published and are now available online at http://ntep.org/zg.htm. Information regarding the performance of several zoysiagrass varieties entered in the 2013 NTEP National Warm-Season Putting Green Test is also available online at: http://www.ntep.org/reports/ws13g/ws13g_15-1/ws13g_15-1.htm.
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