Effect of Cover Crop Management and Preemergence Herbicides on the Control of ALS-Resistant Palmer Amaranth (Amaranthus palmeri) in Peanut
2011
Dobrow, M.H. Jr | Ferrell, J.A. | Faircloth, W.H. | MacDonald, G.E. | Brecke, B.J. | Erickson, J.E.
Palmer amaranth is a troublesome species across the southern US, and has become a serious problem in the SE in recent years. Resistance to acetolactate synthase (ALS) inhibiting herbicides has made control of Palmer amaranth even more difficult for peanut producers. Field studies were conducted in 2008 and 2009 to determine the impact of three rye cover crop management scenarios combined with non-ALS residual herbicides on the duration of control of ALS-resistant Palmer amaranth. Cover crop scenarios included planting into a desiccated rye cover that was left standing, or rolled flat, or no-cover. Within each cover crop scenario five soil residual herbicides were evaluated to determine the duration that each herbicide provided acceptable control of ALS-resistant Palmer amaranth in peanut. Weed counts were conducted weekly to determine the number of Palmer amaranth free days (PFD), which equated to 1 Palmer amaranth per m of row. In 2008, cover crop did not affect the number of PFD and data ranged from 3 to 67 d. In 2009, standing and rolled cover provided greater PFD relative to no-cover. However, herbicide efficacy was reduced in 2009 with PFD ranging between 0.1 and 16 d after treatment. In both years, PFD was ordered as flumioxazin>S-metolachlor (at cracking)>S-metolachlor (preemergence), norflurazon >pendimethalin.
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