Interactions Between Quizalofop-p-ethyl and Acetolactate Synthase-Inhibiting Herbicides in Acetyl-coA Carboxylase Inhibitor-Resistant Rice Production

A field study was conducted in 2015 and 2016 at the H. Rouse Caffey Rice Research Station (RRS) to evaluate antagonistic, synergistic, or neutral interactions of quizalofop when mixed with ALS-inhibiting herbicides labeled in rice production. Quizalofop was applied at 120 g ai ha(-1). Mixture herbicides included penoxsulam at 40 g ai ha(-1), penoxsulam + triclopyr at 352 g ai ha(-1), halosulfuron at 53 g ai ha(-1), bispyribac at 34 g ai ha(-1), orthosulfamuron + halosulfuron at 94 g ai ha(-1), orthosulfamuron + quinclorac at 491 g ai ha(-1), imazosulfuron at 211 g ai ha(-1), and bensulfuron at 43 g ai ha(-1). All ALS herbicides mixed with quizalofop indicated antagonistic responses for red rice, CL-111, CLXL 745, or barnyardgrass control at either 14 or 28 days after treatment (DAT). At 28 DAT, quizalofop mixed with penoxsulam or bispyribac controlled barnyardgrass 34 to 38%, compared with an expected control of 97%. In addition, these same mixtures controlled red rice, CL-111, and CLXL-745 61 to 67% at 28 DAT compared with an expected control of 96 to 97%. A second application of quizalofop at 120 g ha(-1) was applied at 28 DAT. At 42 DAT, neutral responses were indicated for all mixtures except with quizalofop mixed with penoxsulam containing products.