Submitted to: Weed Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/11/2004
Publication Date: 7/15/2005
Citation: Reeves, D.W., Price, A.J., Patterson, M.G. 2005. Evaluation of three winter cereals for weed control in conservation-tillage non-transgenic cotton. Weed Technology. 19:731-736. Interpretive Summary: The increased use of conservation tillage in cotton production requires information be developed on the role of cover crops in weed control. ARS scientists at the Soil Dynamics Research Unit in Auburn, AL and the J. Phil Campbell Sr. Natural Resource Conservation Center, in cooperation with scientists from Auburn University's Cooperative Extension System conducted a field study in Alabama to evaluate the impact of three winter cereal cover crops on weed control and cotton yield in a high-residue conservation tillage production system. A new cover crop from Brazil, black oat, along with rye and wheat were evaluated for their weed-suppressive characteristics compared to a winter fallow system. The cover crops were layed flat on the soil surface with a mechanical roller to form a dense mulch prior to cotton planting. No cover crop was effective in controlling weeds without a herbicide program. However, when black oat or rye was used and a herbicide was applied immediately after cotton planting, weed control was similar to a system that included a second herbicide application. Rye and black oat provided more effective weed control than wheat. This information can be used by State Cooperative Extension Systems, USDA-NRCS, crop consultants, and producers to promote the use of environmentally and economically sustainable conservation practices that reduce herbicide inputs on the 4.2 million acres of cotton grown in the Southeast.
Technical Abstract: The increased use of conservation tillage in cotton production requires information be developed on the role of cover crops in weed control. Field experiments were conducted from fall, 1994 through fall, 1997 in Alabama to evaluate three winter cereal cover crops in a high-residue conservation tillage, non-transgenic cotton production system. Black oat, rye, and wheat were evaluated for their weed-suppressive characteristics compared to a winter fallow system. Three herbicide systems were utilized: no herbicide, preemergence (PRE) herbicides alone, or PRE plus postemergence (POST) herbicides. The PRE system consisted of pendimethalin at 1.12 kg ai/ha plus fluometuron at 1.7 kg ai/ha. The PRE plus POST system contained additional applications of fluometuron at 1.12 kg/ha plus DSMA at 1.7 kg ai/ha early POST-directed (PDS), and lactofen at 0.2 kg ai/ha plus cyanazine at 0.84 kg ai/ha late PDS. No cover crop was effective in controlling weeds without a herbicide program. However, when black oat or rye was utilized with PRE herbicide, weed control was similar to the high input system. Rye and black oat provided more effective for weed control than wheat in conservation-tillage cotton. There was a strong yield benefit for planting conservation-tilled cotton using the Brazilian cover crop management system, i.e., cover crops grown to produce large amounts (>4,480 kg/ha) of residue and then rolled to form a dense mat on the soil surface. The winter fallow, high herbicide input system yielded significantly less cotton two out of three years compared to systems that included a winter cover crop. The Brazilian system using black oat or rye cover crops has potential to increase cotton productivity and reduce herbicide inputs for non-transgenic cotton grown in the Southeast.