Effect of Autumn Management on Winter Annual Weeds Prior to Cotton Planting
2010
Webster, Theodore M.
Field studies were conducted to evaluate the efficacy of autumn tillage and herbicide applications on the control of cutleaf evening-primrose prior to planting cotton. In one study, different timings and combinations of autumn disking and glyphosate applications were evaluated following harvest of the preceding cotton or corn crop. Treatments implemented following corn harvest were inconsistent for annual winter weed control. Relative to the nontreated control, treatments that included disking or glyphosate at 5 wk after harvest (WAH) of cotton had lower cutleaf evening-primrose ground cover estimates and plant population densities, with the exception of glyphosate applied at 5 WAH in 2004. Critical establishment of cutleaf evening-primrose occurred in these studies around 5 wk after cotton harvest (first week of November), whereas post-corn harvest treatments were applied prior to cutleaf evening-primrose establishment. In the second study, pre-plant applications of 2,4-D in three tillage systems were evaluated for cutleaf evening-primrose growth. Application of 2,4-D effectively controlled cutleaf evening-primrose, leaving no green plants at the time of cotton planting. There were differences in the number of cutleaf evening-primrose remnant plants among both tillage and 2,4-D systems. Conventional tillage had fewer cutleaf evening-primrose plants than reduced tillages. Application of 2,4-D to both strip-tillage and no-tillage reduced cutleaf evening-primrose plant density by 70% or greater. Although there was no effect of tillage system on cotton yield, preplant applications of 2,4-D increased cotton growth and yield relative to nontreated controls. 2,4-D was an effective option for cutleaf evening-primrose control prior to cotton planting.
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