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−1was applied at 28 DAT. At 42 DAT, neutral responses were indicated for all mixtures except with quizalofop mixed with penoxsulam containing products.

A field study was conducted in 2015 and 2016 near Crowley, LA, to evaluate antagonistic, synergistic, or neutral interactions of quizalofop when mixed with contact herbicides labeled for use in rice production. Quizalofop was applied at 120 g ai ha−1. Mixture herbicides included bentazon at 1,050 g ai ha−1, carfentrazone at 18 g ai ha−1, propanil at 3,360 g ai ha−1, saflufenacil at 25 g ai ha−1, and thiobencarb at 3,360 g ai ha−1. A second application of quizalofop at 120 g ha−1 was made at 28 d after the initial application (DAIT) to evaluate control of weeds escaping the initial treatment. At 14 and 28 DAIT, red rice, ‘CLXL-745’, and ‘CL-111’ treated with quizalofop plus propanil indicated an antagonistic response with an observed control of 69% to 71% compared with an expected control of 92% to 94%. Barnyardgrass treated with the same mixture also indicated an antagonistic response at 14 and 28 DAIT with an observed control of 16% compared with an expected control of 94%. Barnyardgrass treated with quizalofop plus saflufenacil indicated an antagonistic response at 14 DAIT; however, the same mixture produced a neutral response by 28 DAIT. In addition, a second application of quizalofop was not able to overcome the antagonism observed with a quizalofop plus propanil mixture at 14 and 28 DAIT for red rice, CLXL-745, CL-111, or barnyardgrass control. Quizalofop mixed with carfentrazone or thiobencarb produced a neutral response for all weeds evaluated at each evaluation date.

A glasshouse study was established at Louisiana State University campus in Baton Rouge, LA, to evaluate the control of fall panicum and Nealley’s sprangletop treated with florpyrauxifen-benzyl. Florpyrauxifen was applied at 30 g ai ha–1to each grass species at the three- to four-leaf and one- to two-tiller stages of growth. At 21 d after treatment (DAT), fall panicum control was 91% when treated with florpyrauxifen at the three- to four-leaf stage, and Nealley’s sprangletop control was 78% to 82%, regardless of application timing 21 DAT. Leaf number, tiller number, plant height, and plant fresh weight were reduced when fall panicum and Nealley’s sprangletop were treated with florpyrauxifen. This information can be useful for developing weed management strategies with this herbicide for rice production, and it provides an additional mode of action to help manage and/or delay the development of herbicide-resistant weeds.

A study was conducted near Crowley, Louisiana, to evaluate the efficacy of quizalofop-p-ethyl mixed with different synthetic auxin and ACCase-inhibiting herbicides for barnyardgrass and weedy rice control in rice production systems. Quizalofop was applied at 0 or 120 g ai·ha−1 mixed with 2,4-D at 1336 g ai·ha−1, triclopyr at 282 g ai·ha−1, quinclorac at 420 g ai·ha−1, cyhalofop-butyl at 314 g ai·ha−1, or fenoxaprop-p-ethyl at 122 g ai·ha−1. Cyhalofop, fenoxaprop, 2,4-D, quinclorac, and triclopyr antagonized quizalofop for barnyardgrass control at 14 days after treatment (DAT). At 28 DAT, an antagonistic response persisted for barnyardgrass control, except when cyhalofop was mixed with quizalofop, which indicated a neutral response. Red rice, CLXL-745, and CL-111 control decreased due to antagonism of quizalofop when mixed with 2,4-D. However, quinclorac, triclopyr, cyhalofop, or fenoxaprop mixed with quizalofop resulted in a neutral response for red rice, CLXL-745, and CL-111 control at 28 DAT.

A glasshouse study was conducted on the Louisiana State University campus in Baton Rouge, LA, to evaluate the control of brook crowngrass, rice cutgrass, southern watergrass, and water paspalum. Florpyrauxifen-benzyl was applied at 30 g ai ha−1 to each grass species at the 3- to 4-leaf or 1- to 2-stolon stage of growth. Brook crowngrass treated with florpyrauxifen was controlled 71% at 21 d after treatment. Southern watergrass and water paspalum control did not exceed 56% and 36%, respectively, across all evaluations. Rice cutgrass treated with florpyrauxifen did not reach 15% control. Plants treated with florpyrauxifen, except rice cutgrass, displayed reduction in leaf number, stolon number, plant height, and plant fresh weight. These results indicate florpyrauxifen-benzyl can help manage a brook crowngrass infestation and suppress southern watergrass. However, florpyrauxifen-benzyl has little to no activity on water paspalum and rice cutgrass, and other management options should be employed if these weeds are present.