A study was conducted to evaluate weed control with imazethapyr applied at different timings or a combination of timings with or without an early POST application of bensulfuron, bentazon plus aciflurofen, bispyribac, carfentrazone, halosulfuron, propanil plus molinate, or triclopyr in drill-seeded imidazolinone-resistant rice. Control of barnyardgrass, red rice, and alligatorweed was insufficient with imazethapyr at 87 g/ha PRE or at 53 g/ha late POST alone. Imazethapyr at 87 g/ha PRE followed by imazethapyr at 53 g/ha late POST controlled red rice 86% or greater but did not control hemp sesbania. The imazethapyr PRE followed by late POST combination was also weak on barnyardgrass and alligatorweed early in the season. The addition of an early POST application of the other herbicides to the imazethapyr combination improved overall weed control, especially hemp sesbania control. Among the early POST herbicides, bispyribac, carfentrazone, or propanil plus molinate were more effective in helping improve the overall weed control, resulting in better rice grain yield.
Nomenclature: Aciflurofen, bensulfuron, bentazon, carfentrazone, bispyribac, halosulfuron, imazethapyr, molinate, propanil, triclopyr, alligatorweed, Alternanthera philoxeroides (Mart.) Griseb. #3 ALRPH, barnyardgrass, Echinochloa crus-galli (L.) Beauv. # ECHCG, hemp sesbania, Sesbania exaltata (Raf.) Rydb. ex A.W.Hill # SEBEX, red rice, Oryza sativa L. # ORYSA, rice, Oryza sativa L., imidazolinone-resistant ‘93 AS-3510’ and ‘CL 121’.
Additional index words: ALS, acetolactate synthase, Clearfield rice.
Abbreviations: ALS, acetolactate synthase; DAT, days after LPOST treatment; EPOST, early postemergence; fb, followed by; IR, imidazolinone-resistant; LPOST, late postemergence; LSU, Louisiana State University.
