Tall fescue interseeding and postemergence herbicides for false-green kyllinga (Kyllinga gracillima) control in turfgrass

Abstract

AbstractFalse-green kyllinga is a problematic C4 perennial Cyperaceae species. Previous research examined herbicide efficacy but has not integrated nonchemical practices with herbicides. Replicate field experiments were conducted to evaluate late-summer postemergence applications of herbicides in combination with turf-type tall fescue interseeding for false-green kyllinga control. Seven herbicide treatments and a nontreated control formed a complete factorial, with tall fescue interseeding or no seeding (eight-by-two factorial). Six herbicide treatments consisted of single postemergence applications of halosulfuron-methyl (70 g ha–1), imazosulfuron (420 g ha–1), and sulfentrazone + carfentrazone (280 + 30 g ha–1) applied 4 wk before tall fescue interseeding (WBS) and the day of interseeding. Glyphosate (220 g ae ha–1) applied the day of interseeding was the seventh herbicide treatment. Tall fescue was interseeded in September, and false-green kyllinga control was evaluated the following summer. In combination with tall fescue interseeding, imazosulfuron and halosulfuron applied 4 WBS as well as glyphosate applied the day of interseeding controlled false-green kyllinga better than all other treatments. In July, imazosulfuron and halosulfuron treatments applied 4 WBS and combined with interseeding had 1% to 6% false-green kyllinga cover, respectively, compared to 28% and 62% cover, respectively, without interseeding. Interseeding alone controlled false-green kyllinga <50%. Imazosulfuron, halosulfuron, and sulfentrazone + carfentrazone applied the day of seeding severely injured emerging tall fescue seedlings and reduced turfgrass quality the following spring. Applying imazosulfuron or halosulfuron in late summer and interseeding turf-type tall fescue 4 wk later or applying glyphosate the day of seeding are effective strategies for postemergence false-green kyllinga control. Integrating herbicides and the cultural practice of tall fescue interseeding provided more false-green kyllinga control than either practice alone.