Mowing and Nitrogen Influence Green Kyllinga (Kyllinga brevifolia) Infestation in Tifway Bermudagrass (Cynodon dactylon×C. transvaalensis) Turf¹

Abstract

A field study evaluated the effects of green kyllinga establishment method (seed vs. stolon), two mowing heights (2.5 and 5.0 cm), and three nitrogen (N) rates (0, 24, and 49 kg/ha/mo) on green kyllinga infestation in ‘Tifway’ bermudagrass turf. The study was initiated in vigorous and newly established or “weak” bermudagrass turf in May 1997 and continued until December 1998. The green kyllinga area was measured periodically each year and plant dry weight (g/500 cm2) was calculated in December 1997 and 1998. In 1997, stolon established green kyllinga plots were twice as large as seeded plots in vigorous turf and four times larger in weak turf. Method of establishment, however, was less important in 1998 as seedling populations became more established. In weak turf, increasing N rate to 49 kg/ha/mo decreased green kyllinga spread by 50% in 1997 and by 40% in 1998 compared to no N. In vigorous turf, mowing height influenced green kyllinga infestation more than N. Low mowing height (2.5 cm) increased green kyllinga infestations nearly twofold in vigorous turf in 1997 and more than fivefold in 1998. Golf course fairways are often maintained at clipping heights shorter than 2.5 cm, and green kyllinga is a prevalent weed at these sites. Green kyllinga may gain a competitive advantage in bermudagrass turf at lower mowing heights.

Cultural Management of Weeds in Turfgrass

“…In the same study, low mowing height (1.3 cm) of green kyllinga, also in the absence of competition, reduced shoot number and plant spread, and the same effects were noticed at a 3.8‐cm mowing height, but not until the final evaluation. As noted earlier, a 2.5‐cm mowing height increases green kyllinga, compared with a 5.0‐cm mowing height, in a situation with competition from turfgrass (Lowe et al, 2000). An environmental stress such as close mowing may be harmful to weeds such as green kyllinga or even crabgrasses, but may be even more harmful to turfgrasses; therefore, weeds are given a relative advantage in a competitive environment.…”

“…Low mowing height (2.5 cm) increases green kyllinga ( Kyllinga brevifolia Rottb.) infestation 2 to 5 times in bermudagrass turf, compared with a 5.0‐cm mowing height (Lowe et al, 2000). Species of Kyllinga , a relatively low growing, spreading weed, are highly competitive with bermudagrass (Kawabata et al, 1994).…”

“…In weak Tifway bermudagrass turf, increasing N rate to 49 kg N ha −1 per month decreases green kyllinga spread by 40 to 50% (Lowe et al, 2000). Bermudagrass is a relatively quick‐growing grass with maximum compound growth rate of 9.2% d −1 (Busey and Myers, 1979), and its growth responds strongly to high N fertilization when there is adequate temperature and sunlight.…”

Influence of Cultural Practices on Torpedograss Competition with Two Warm-Season Lawn Grasses

“…Calhoun et al (6) reported a fertilized cool‐season mixture of Kentucky bluegrass, perennial ryegrass ( Lolium perenne L.), and fine fescue ( Festuca rubra L.) reduced broadleaf weed infestation compared to non‐fertilized areas. Lowe et al (18) noted increasing N to 49 kg/ha/month reduced green kyllinga ( Kyllinga brevifolia Rottb.) spread 40% to 50% in sparse ‘Tifway’ bermudagrass.…”

False-green kyllinga (Kyllinga gracillima) control in cool-season turfgrass

“…Elmore, unpublished observation). Green kyllinga is more competitive in turfgrass at low (2.5 cm) mowing heights than higher (5.0 cm) heights (Lowe et al 2000). Both species produce flowering culms below golf course fairway mowing heights of 1.3 cm (Bryson et al 1997).…”