Field studies were conducted during the 2002 thru 2004 growing seasons at two locations in the south-central Texas cotton-production region to evaluate trifloxysulfuron and trifloxysulfuron plus prometryn in combination with either S-metolachlor or glyphosate or both for weed control and cotton response. Cotton leaf burn (13 to 19%) was noted in 2002 at one location with trifloxysulfuron plus prometryn applied late POST-directed (LPDIR). Herbicide combinations that included trifloxysulfuron controlled barnyardgrass, hemp sesbania, yellow nutsedge, Palmer amaranth, smooth pigweed, ivyleaf morningglory, pitted morningglory, and smellmelon at least 80% in most instances. Glyphosate applied early POST over-the-top (EPOTT) and mid-POST over-the-top (MPOTT) at 0.84 kg ai/ha followed by trifloxysulfuron plus prometryn at 1.1 kg ai/ha applied LPDIR controlled the above-mentioned weeds plus Texas panicum at least 94%. No other herbicide systems provided effective control (greater than 79%) of Texas panicum. Higher cotton yields in 2002 were obtained with herbicide systems that included glyphosate alone or glyphosate plus S-metolachlor applied EPOTT or LPOTT followed by trifloxysulfuron plus prometryn applied LPDIR, whereas in 2003, none of the herbicide systems increased yield over the nontreated check.

Nomenclature: Glyphosate; S-metolachlor; trifloxysulfuron; prometryn; trifloxysulfuron; barnyardgrass, Echinochloa crus-galli L. ECHCG; hemp sesbania, Sesbania exaltata (Raf.) Rydb. Ex A.W. Hill SEBEX; ivyleaf morningglory, Ipomoea hederacea (L.) Jacq. IPOHE; Palmer amaranth S. Wats, Amaranthus palmeri S. Wats AMAPA; pitted morningglory, Ipomoea lacunose L. IPOLA; smellmelon, Cucumis melo L. var. Dudaim Naud CUMME; smooth pigweed, Amaranthus hybridus L., AMACH; Texas panicum, Panicum texanum Buckl. PANTE; yellow nutsedge, Cyperus esculentus L. CYPES; cotton, Gossypium hirsutum L. ‘Deltapine 422BRR’, ‘Deltapine 434RR’, ‘Deltapine 436RR’, ‘Deltapine 555RR’, ‘Stoneville 4892BR’.