Tropical signalgrass (Urochloa subquadripara) control with preemergence- and postemergence-applied herbicides

• Published in: Weed technology Vol. 18; no. 2; pp. 419 - 425
• Main Authors: Teuton, T.C, Unruh, J.B, Brecke, B.J, MacDonald, G.E, Miller, G.L, Ducar, J.T
• Format: Journal Article
• Language: English
• Published: Lawrence, KS Weed Science Society of America 01-04-2004
• Subjects: Agricultural soils; Biological and medical sciences; Chemical control; Fertilizer application timing; Fundamental and applied biological sciences. Psychology; Germination; Herbicides; Organic farming; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; postemergent weed control; preemergent weed control; Sand; Seedlings; Soil organic matter; Turf grasses; Urochloa; Web pages; Weeds; Florida; DIGLO; Weed science; Tropical zone; PANRE; Pesticides; Preemergence; Postemergence; BRASU; Herbicide; DIGSO
• ISSN: 0890-037X; 1550-2740
• DOI: 10.1614/WT-03-155R1

Tropical signalgrass is one of the most serious weed problems in the St. Augustinegrass sod production in Florida, and its presence increases production costs and lowers turfgrass quality. The objectives of our research were to: (1) evaluate herbicides preemergence and postemergence for control of tropical signalgrass and (2) compare control of tropical signalgrass and other problem weeds (torpedograss, blanket crabgrass, and India crabgrass) with postemergence herbicides. In preemergence herbicide field trials, only benefin + oryzalin, imazapic, imazapic + 2,4-D, and oryzalin provided ≥75% tropical signalgrass control 8 wk after application (WAA). By 11 WAA, only benefin + oryzalin and imazapic + 2,4-D provided ≥75% tropical signalgrass control. In greenhouse experiments, eight herbicide treatments were applied postemergence to tropical signalgrass seedlings at the two-, four-, six-, and eight-leaf stages. Asulam and CGA 362622 provided ≥89% tropical signalgrass control at all application timings. Imazaquin controlled tropical signalgrass ≥98% when applied before the eight-leaf stage. However, in field trials with mature tropical signalgrass (>20 cm stolons), none of the 20 herbicide treatments applied postemergence provided acceptable control.