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arrow Characteristics of Kyllinga species
Key Points

Because some popular herbicides won't kill them, grass-like Kyllinga species are apparently becoming more common on golf courses.

Research indicates that some pre-emergence herbicides are effective against these weeds.

Post-emergence control requires repeated treatments.

GCM flag

Kyllinga weeds defy some herbicides

Several species offer new challenges for superintendents

Todd Lowe; Bert McCarty, Ph.D.; and Ted Whitwell, Ph.D.

Sedges are common turfgrass weeds that favor warm climates and poorly drained or over-irrigated areas. Golf courses often provide ideal environments for sedges, where some of the more common species include purple nutsedge, yellow nutsedge, globe sedge, rice flat sedge, annual sedge and Kyllinga species (10).

Kyllinga species can mar a stand of bermudagrass as well as other turf.
Kyllinga species

Kyllinga species are becoming more prevalent on golf courses. Forty-five Kyllinga species exist, but only five are found in the continental United States, with one additional species occurring in Hawaii (6,7,9). Most are rather difficult to detect in turfgrass. Kyllinga leaves, however, are glossier than turfgrass leaves and are detected more easily in the morning when dew runs off their leaves while the turf remains wet. Kyllinga species also have a distinctive "minty sweet" scent when their leaves are mowed or crushed.

Perennial species
Green kyllinga (Kyllinga brevifolia) is the most commonly known turf weed of the genus. It has a rhizomatous and stoloniferous growth, and the stolons (runners) intertwine within turf to produce thick mats. Repeated herbicide applications are generally required to remove green kyllinga because herbicides only contact the outer surface (1,11). Effective products include Image (imazaquin), Basagran (bentazon), MSMA (monosodium methanearsonate) and Manage (halosulfuron).

Kyllinga mats generally begin small (2-3 square feet) but may increase in size and choke out surrounding turfgrass.

Green kyllinga produces viable seed throughout the growing season. When unmowed, its seedheads are about the size of a garden pea and have a light green color. Seeds initiate germination in spring and continue throughout the summer.

A closely related perennial species is false green kyllinga (K. gracillima). It too is rhizomatous and about the same size as green kyllinga. False green kyllinga seedheads are less oval than those of green kyllinga. The major difference between these species is timing of seedhead production. Green kyllinga creates seedheads throughout the growing season, whereas false green kyllinga creates seedheads only in late summer or early fall.

Another perennial species in the continental United States is fragrant kyllinga (K. odorata). Fragrant kyllinga was once termed "annual kyllinga," but it is, in fact, a perennial species. Fragrant kyllinga is named for the sweet aroma it releases when its leaves are mowed or crushed.

Unlike the other mat-forming perennial species, fragrant kyllinga is tufted or bunchy rather than rhizomatous. Its seedheads are white and generally three-lobed, making them look like torpedoes or inverted Ys.

Annual species
Annual Kyllinga species are tufted, shallow-rooted and can be easily pulled from turf. The species with widest distribution in the continental U.S. is tufted kyllinga (K. pumila). It was recorded as far north as Pennsylvania and Kansas and in the south from Texas to Florida (5). Tufted kyllinga has no rhizomes or stolons; growth proceeds from the base of each plant. It resembles green kyllinga in size and seedhead shape, but closer examination reveals its tufted growth and lack of stolons.

A species becoming more troublesome on golf courses is cock's comb kyllinga (K. squamulata). Cock's comb kyllinga is tufted but is larger than tufted kyllinga. Cock's comb kyllinga derives its name from its seed shape. Small spurs on the edge of the seed resemble a rooster's comb.

In fairways and roughs, cock's comb kyllinga is easily detected because it characteristically grows taller than the surrounding turf canopy. Cock's comb kyllinga plants also are generally light green or yellowish in color.

Pre-emergence control studies
Kyllinga species are considered new weed species in turfgrass largely because of changing herbicide trends (3,4). According to our research at Clemson University, dinitroaniline pre-emergence herbicides have apparently provided a niche for Kyllinga because these popular materials appear to offer poor control of the species. Our studies in 1997 and 1998 evaluated pre-emergence control of green kyllinga and cock's comb kyllinga by commercially available turfgrass herbicides.

Materials and methods
Studies were performed in Tifway bermudagrass plots in Clemson, S.C. The green kyllinga control study was initiated in July 1997, and the cock's comb kyllinga study was initiated in May 1998.

Treatments included one application of Barricade (prodiamine) at 0.75 pound of active ingredient per acre, Dimension (dithiopyr) at 0.5 pound, Pendulum (pendimethalin) at 3 pounds, Pennant (metolachlor) at 4 pounds, Ronstar (oxadiazon) at 2 pounds, simazine at 1.5 pounds and sulfentrazone at 0.5 pound. Sulfentrazone is an experimental herbicide under development by FMC. All treatments were liquid applications using 8004 flat fan nozzles at a rate of 30 gallons per acre.

False green kyllinga (left) is similar to green kyllinga.
False green kyllinga

Kyllinga control
Ronstar provided the best green kyllinga control (93 percent). No other treatments effectively controlled green kyllinga.

Ronstar and sulfentrazone also provided good cock's comb kyllinga control (greater than 89 percent). Sulfentrazone offers good post-emergence green kyllinga and purple nutsedge control (2,8) but also has pre-emergence control activity. Pendulum, Dimension and Pennant provided 34-60 percent control. As expected, the dinitroaniline herbicides (Barricade and Pendulum) were ineffective at controlling either Kyllinga species.

Treatments were applied only once in our studies, and repeat applications may offer greater Kyllinga control.

Minimally acceptable bermudagrass injury (less than 20 percent) followed Ronstar and sulfentrazone applications at 1 and 2 weeks. No treatment injured turf beyond 3 weeks.

Barricade, Pendulum and Dimension are often used by golf course superintendents for pre-emergence control of annual grasses such as crabgrass. Although these herbicides may be less expensive, only slight Kyllinga control was observed at two months following treatment with these herbicides. This helps confirm the observations that Kyllinga species are becoming more prevalent on golf courses after prolonged pre-emergence herbicide use.

Literature cited

1. Blum, R.R., and F.H. Yelverton. 1997. Green kyllinga (Kyllinga spp.) and purple nutsedge (Cyperus esculentus) control in bermudagrass turf. Southern Weed Science Society Proceedings 50:40.
2. Brecke, B.J., J.B. Unruh and M.W. Edenfield. 1999. Long-term control of purple nutsedge. Golf Course Management 67:61-64.
3. Bryson, C.T., R. Carter, L.B. McCarty and F.H. Yelverton. 1997. Kyllinga, a genus of neglected weeds in the continental United States. Weed Technology 11:838-842
4. Bunnell, B.T., L.B. McCarty, D.B. Lowe, T. Whitewall and J.F. Higingbottom. 1998. Pre- and early post-emergence control of Kyllinga in turf. Southern Weed Science Society Proceedings 51:74.
5. Delahoussaye, A.J., and J.W. Thieret. 1967. Cyperus subgenus Kyllinga (Cyperaceae) in the continental United States. SIDA 3(3):128-136.
6. Kawabata, O., R.K. Nishimoto and C. Tang. 1994. Interference of two Kyllinga species (Kyllinga nemoralis and Kyllinga brevifolia) on bermudagrass growth. Weed Technology 8:83-86.
7. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Vol. 1. Timber Press, Portland, Ore.
8. Lowe, D.B., and T. Whitwell. 1997. Seedling Kyllinga management in nursery crops. Southern Nurserymen's Association Proceedings 42:319-321.
9. Tucker, G.C. 1984. A revision of the genus Kyllinga Rottb. (Cyperaceae) in Mexico and Central America. Rhodora 86:508-539.
10. Yelverton, F.H. 1996. Know your sedges. Golf Course Management 64:56-60.
11. Yelverton, F.H., and L.B. McCarty. 1996. Green kyllinga (Kyllinga brevifolia) control in bermudagrass turf. Southern Weed Science Society Proceedings 49:68.

Todd Lowe is a turfgrass research assistant at Clemson (S.C.) University.
Bert McCarty, Ph.D., and Ted Whitwell, Ph.D., are professors in the horticulture department at Clemson.