| Abstract/Contents: | "Horsenettle (Solanum carolinense), groundsel (Senecio tomentosa), red sorrel (Rumex acetosella), dogfennel (Eupatorium capillifolium), wild garlic (Allium vineale), and cancerweed (Salvia lyrata) are problem herbaceous perennial weeds in Arkansas pastures. A field experiment to evaluate herbicides for horsenettle control was established in July 1983. One year after treatment, dicamba at 0.5, 1.0 and 2.0 lb ai/A and dicamba + 2, 4-D at 0.25 + 0.7, 0.5 + 1.4 and 1.0 + 2.8 lb/A provided less than 50% control. Picloram at .5 and 1.0 lb/A provided 50 and 95% control, respectively. A second study was initiated in July 1991 to evaluate newly registered pasture weed control herbicides for horsenettle control. In this study, one year after treatment, metsulfuron, 2, 4-D, and dicamba + 2, 4-D were providing less than 40% horsenettle control. The most effective treatments were picloram + 2, 4-D at 0.4 + 1.5 and 0.54 + 2.0 lb/A, providing 85 and 88% control, respectively. Intermediate treatments were picloram + 2, 4-D at 0.27 + 1.0 lb/A and 2, 4-D + picloram + metsulfuron at 0.14 + 0.5 + 0.004 lb/A which provided 60 and 67% control, respectively. Anecdotal reports have indicated that common groundsel is not controlled by 2, 4-D or dicamba + 2, 4-D, the two most commonly used pasture herbicides in Arkansas. An unreplicated study conducted in 1991 suggested that picloram + 2, 4-D and metsulfuron had potential for control of common groundsel. Metsulfuron at 0.013 and 0.019 lb/A was giving 99% control, and picloram + 2, 4-D at 0.27 + 1.0 and 0.4 + 1.5 lb/A provided 60 and 85% control, respectively, 42 days after treatment. In a replicated trial, conducted in 1992, 2, 4-D and 2, 4-D + dicamba provided less than 50% control. Metsulfuron was the most effective treatment with rates of 0.004, 0.008 and 0.013 lb/A providing 72, 83 and 95% control, respectively. The most effective growth regulator herbicide combination was picloram + 2, 4-D at 0.27 + 1.0 lab/A which provided 73% control. Two studies were conducted in 1989 and repeated in 1991 to evaluate current recommendations and compare metsulfuron, 2, 4-D ester, picloram + 2, 4-D and dicamba + 2, 4-D for dogfennel control. Metsulfuron was the least effective treatment providing less than 50% control at 0.013 lb/A. Treatments providing greater than 90% control were dicamba + 2, 4-D at 0.25 + 0.7 lb/A, picloram + 2, 4-D at 0.14 + 0.5 lb/A and 2, 4-D ester at 1.4 lb/A. In a study conducted in Johnson County in 1991 and repeated again in Faulkner County in 1994, metsulfuron at 0.019 lb/A, dicamba + 2, 4-D at 0.25 + 0.7 lb/A and picloram + 2, 4-D at 0.14 + 0.5 applied in April, provided greater than 90% control of red sorrel. Triasulfuron at 0.035 lb/A and 2, 4-D ester at 1.4 lb/A and provided less than 50% red sorrel control. Four studies conducted in 1989 and 1991 showed that metsulfuron, glyphosate and paraquat were effective herbicides for wild garlic control in pastures. Metsulfuron, at 0.013 lb/A, glyphosate at 1.0 lb/A and paraquat at 0.56 lb/A provided greater than 90% control of wild garlic in each of these experiments. In 1993 and 1994 studies were conducted to evaluate herbicides for cancerweed control. In 1993, applications of picloram + 2, 4-D at 0.135 + 0.5 lb/A and metsulfuron at 0.016 lb/A were made in mid-June resulting in 47 and 60% control of cancerweed, respectively. The same treatments were more effective the next year when applied in early April providing 80 and 98% control of cancerweed, respectively." |
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