Effectiveness of Sulfosulfuron and Quinclorac for Weed Control during Switchgrass Establishment

• Published in: Weed technology Vol. 25; no. 4; pp. 598 - 603
• Main Authors: Curran, William S, Ryan, Matthew R, Myers, Matthew W, Adler, Paul R
• Format: Journal Article
• Language: English
• Published: 810 East 10th St., Lawrence, KS 66044-7050 Weed Science Society of America 01.10.2011; Cambridge University Press
• Subjects: Aboveground biomass; Amaranthus hybridus; Bioenergy; Biomass; Biomass production; chlorosis; Colleges & universities; Competition; Energy crops; Experiments; field experimentation; Grass weeds; Grasses; Growth retardation; Herbicides; Hypochromic anemia; Panicum virgatum; perennial grass; planting; quinclorac; seed oils; Setaria pumila subsp. pumila; surfactants; Tillers; Weed control; WEED MANAGEMENT—OTHER CROPS/AREAS; Weeds; United States > US
• ISSN: 0890-037X; 1550-2740
• DOI: 10.1614/WT-D-11-00010.1

We conducted a field experiment in 2007 and 2008 and repeated it in a separate field in 2008 and 2009 to test the effectiveness of two herbicides applied at two different times on weed control during switchgrass establishment. At 4 and 6 wk after switchgrass planting (WAP), sulfosulfuron was applied at 0.04 and 0.07 kg ai ha−1 with nonionic surfactant and quinclorac was applied at 0.28, 0.42, and 0.56 kg ai ha−1 with methylated seed oil. Herbicides applied at 4 WAP tended to be more effective than at 6 WAP. Sulfosulfuron provided greater control of smooth pigweed; however, quinclorac provided greater control of yellow foxtail, a grass weed that has traditionally been difficult to control with herbicides in switchgrass. Average yellow foxtail control was 73, 87, and 93% for quinclorac at 0.28, 0.42, and 0.56 kg ha−1, respectively, compared to 62 and 60% for sulfosulfuron at 0.04 and 0.07 kg ha−1, respectively. Switchgrass injury (chlorosis and height reduction relative to the untreated control) was observed, but most symptoms were not detectable by 8 wk after treatment (WAT) for most treatments. Plots that received quinclorac at 0.56 kg ha−1 at 6 WAP tended to have relatively low weed biomass and high total aboveground yield in the establishment year and relatively high total aboveground yield in the year after establishment. Nomenclature: Quinclorac; sulfosulfuron; smooth pigweed, Amaranthus hybridus L.; yellow foxtail, Setaria pumila (Poir.) Roemer & J.A. Schultes; switchgrass, Panicum virgatum L.