| Abstract/Contents: | "Three field trials were conducted during the 1998 and repeated in 1999 to evaluate mugwort (Artemesia vulgaris L.) control with several herbicides and herbicide/mowing regimes. A logarithmic sprayer was utilized in the first field trial to determine herbicide rates that provide acceptable mugwort control. Sequential herbicide treatments were applied to mugwort at 7-week intervals in the second field trial to evaluate mugwort control following one, two, and three herbicide applications. In the third field trial, the effect of sequential mowing was investigated by applying herbicides to mugwort regrowth following either one or two mowings. The herbicides evaluated in all three field trials included 2,4-D amine, 2,4-D ester, dicamba, triclopyr, clopyralid, picloram, metsulfron, glyphosate, and glufosinate. Pelargonic acid was also evaluated as an addition to 2,4-D amine, glyphosate, and glufosinate in the logarithmic sprayer trial. In the logarithmic sprayer trial, all herbicides except for metsulfuron were evaluated at the rates of 8, 4, 2, 1, 0.5, and 0.25 lb ai per acre. Metsulfuron was evaluated at an analogous rate range with the highest rate being 0.56 ai per acre. In the sequential herbicide and sequential mowing trials, 2,4-D amine, 2,4-D ester, and glyphosate were applied at 4.0 lb ai per acre, triclopyr and dicamba at 2.0 lb ai per acre, glufosinate at 1.5 lb ai per acre, picloram at 1.0 lb ai per acre, clopyralid at 0.25 lb ai per acre, and metsulfuron at 0.0112 lb ai per acre. In the logarithmic sprayer trial, 100% control of mugwort was achieved with all rates of picloram during both years. In 1998, all rates of clopyralid provided greater than 95% control of mugwort. In 1999, however, slightly lower levels of control were observed at the 0.25, 0.5, 1.0 and 2.0 lb clopyralid rates. The next highest level of mugwort control was achieved with the 8, 4, and 2 lb glyphosate rates, which provided greater than 90% control in both years. Dicamba also provided greater than 90% mugwort control at the 8 lb rate during both years. All remaining herbicides generally provided unacceptable control of mugwort. Sequential herbicide treatment trials conducted during both years revealed that only one application of picloram was required to provide 100% mugwort control. Additionally, two or three treatments of clopyralid or glyphosate did not significantly enhance mugwort control compared to one application of these herbicides. In 1998, a second application of 2,4-D amine, 2,4-D ester, dicamba, or triclopyr significantly improved mugwort control, however a third application of any of these herbicides was not warranted. Mugwort control was also significantly improved with each additional application of glufosinate in 1998. In the sequential mowing trial, two mowings did not significantly enhance mugwort control in the clopyralid, dicamba, metsulfuron, picloram, or triclopyr treatments in either year. In 1998, a second mugwort mowing significantly improved mugwort control in plots treated with 2,4-D amine, 2, 4-D ester, glyphosate, and glufosinate. In 1999, however, the second mowing only enhanced mugwort control in plots treated with 2,4-D ester and glufosinate." |
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