|Grey, T - University Of Georgia|
Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/22/2010
Publication Date: 6/1/2010
Citation: Webster, T.M., Scully, B.T., Grey, T.L. 2010. The effect of winter cover crop planting date on Palmer amaranth (Amaranthus palmeri) suppression in cotton and peanut. Proceedings of Southern Weed Science Society. 63:92.
Technical Abstract: Herbicide resistant Palmer amaranth (PA) has rapidly become the dominant weed management issue in agronomic crops of the Southeast U.S. The small size of PA seeds relative to other common weeds may provide an opportunity for physical weed control through cover crop mulches. Field studies were conducted at the USDA-ARS Jones Farm near Chula, GA to evaluate the influence of high residue cover crop mulches (seeding rates of 100 kg/ha) on PA emergence and control. Treatments were a 3X4 factorial in both cotton and peanut, with three levels of rye planting dates and four levels of weed control programs. Following rye anthesis, plots were rolled forming a horizontal mulch mat. Herbicide programs in cotton and peanut included the two best resistance management programs, a nontreated control, and a banded application. Broadcast applications in both crops controlled PA >95%; there were no treatment by mulch interactions. In the nontreated controls, PA densities were 6 to 9 plants/m2, while PA biomass was 1.2- to 2.5-X larger in cotton relative to peanut. Peanut crop yield was reduced in the control relative to the best treatments. In cotton, PA interference in the nontreated control reduced crop canopy volume and prevented harvest. Herbicides in this study were effective in controlling PA due to the low-level of naturalized herbicide resistance in the PA population at this farm. High level of control likely masked the benefits of high-residue cover crop mulches that have been observed in related companion studies in Georgia.