Location: Crop Protection and Management Research
Title: Rye-legume winter cover crop mixtures and Palmer amaranth (Amaranthus palmeri) Authors
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 18, 2011
Publication Date: June 18, 2011
Citation: Webster, T.M., Scully, B.T., Culpepper, A.S. 2011. Rye-legume winter cover crop mixtures and Palmer amaranth (Amaranthus palmeri). Weed Science Society of America Meeting Abstracts. 64:59. Technical Abstract: The development of glyphosate-resistant Palmer amaranth is a significant challenge for cotton production in Georgia and much of the Southern US. Winter cover crops, rye and rye mixtures with legumes, were evaluated for weed suppression and their influence on cotton production. Two studies were initiated on in the autumn of 2008 and 2009 near Ideal, GA and near Chula, GA in areas with naturalized Palmer amaranth. The first study evaluated main plot treatments of cover crops: rye, blue lupin, crimson clover, Austrian winter pea, and cahaba vetch. Each of the legumes was evaluated alone and in mixture with rye. The second study evaluate rye+lupin, rye+clover, and fallow with four rates of supplemental nitrogen applied to cotton. Cover crop biomass was greatest with rye and lupin. Averaged over all legumes, biomass more than doubled when rye was planted in mixture compared to the legume alone. Palmer amaranth populations were seven-times greater in the cotton row where soil was disturbed compared to the undisturbed row middles. Rye+Legumes had greater weed suppression than monocultures. Rye and pea suppressed Palmer amaranth >80% in mid-June and suppression was related to cover biomass. Yield in plots treated with an effective herbicide program had similar cotton yields among cover crops. Where herbicides were not used, cotton could not be harvested, regardless of cover crop. Effective cover crop use hinges on Palmer amaranth control in the cotton row, which is still elusive.