Weed Control Systems for Conservation-Tillage Cotton

Robert Frans, Marilyn McClelland, and Cade Smith


Adoption of conservation-tillage systems by cotton producers has been occasioned by increasing concerns over soil loss due to erosion and by increased environmental awareness. Intensive soil tillage practices are destructive of good soil tilth and lead to rapid depletion of soil organic matter and decreased fertility. The Conservation Compliance Provision of the 1985 Food Security Act encourages consideration of alternative production systems, particularly on erodible cropland. Adoption of such systems, however, demands a change in weed management practices employed, particularly in southeastern US, the so-called "rain-fed" production area. The greatest change is in practices imposed prior to planting. In minimum-tillage or no-tillage systems, preplanting "burndown" herbicides are employed to destroy winter vegetation or cover crops before planting, and are combined with preemergence herbicides at planting. It is often necessary to apply the preplanting burndown herbicides twice to insure adequate weed destruction before planting.

Experiments have been conducted for two years on a clay and silt loam soil using no-till management practices. Herbicides evaluated for winter weed destruction prior to planting included glyphosate, paraquat, and glufosinate applied from late February to late March. Control of horseweed (Conyza canadensis [L.]Cronq.) with glyphosate was enhanced by the addition of oxyfluorfen, and the mixture of paraquat and oxyfluorfen improved control of cutleaf eveningprimrose (Oenothera laciniata Hill), Pennsylvania smartweed (Polygonum pensylvanicum Hill), and henbit (Lamium amplexicaule L.) over that obtained with paraquat alone. Control of cutleaf eveningprimrose was improved by adding cyanazine to glyphosate, but the mixture was antagonistic in its effect on little barley (Hordeum pusillum Nutt.) on the clay soil. The herbicide DPX-PE350 (Staple) was effective in controlling cutleaf eveningprimrose and Pennsylvania smartweed before planting.

Regardless of control of winter weeds, all plots required a burndown application of glyphosate or paraquat at planting to control emerging summer annuals. These were applied in mixture with the preemergence herbicides. The generally excellent control we have obtained with these preplant applications in no-tillage cotton has been maintained with standard applications of preemergence herbicides, such as fluometuron plus metolachlor, and directed applications of cyanazine plus MSMA. Average cotton yields from the no-till plots equalled that from plots that were managed with conventional production practices.

Our results with conservation-tillage cotton to date indicate that weed management practices and systems should provide adequate control. Our work with these systems will continue, and emphasis is being placed on economics of control as well as ability to combine these practices with other production inputs.

This study was funded in part by Cotton Incorporated through the Arkansas State Support Program.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 1696
©National Cotton Council, Memphis TN

[Main TOC] | [TOC] | [TOC by Section] | [Search] | [Help]
Previous Page [Previous] [Next] Next Page
Document last modified Sunday, Dec 6 1998