Wesley J. Everman1, Scott B. Clewis1, David L. Jordan1, John W. Wilcut1, Jason W. Weirich2, D.R. Shaw3, W. G. Johnson2, S. C. Weller2, M.K.D. Owen2, R. G. Wilson2, and B. G. Young2. (1) North Carolina State University, Campus Box 7620 Williams Hall, Raleigh, NC 27695, (2) 117 Dorman Hall, Mississippi State, MS 39762, (3) Mississippi State University, 82 Stoneville Rd, P.O. Box 197, Stoneville, MS 38776
In 2006, a 4-year study was established to evaluate the temporal aspects of weed populations in Roundup Ready production systems in 6 states. A survey was conducted prior to study initiation to determine grower perceptions and practices in various Roundup Ready cropping systems throughout the country. During the initial year of the study, we identified producer fields currently in continuous Roundup Ready cotton systems, split them into producer and researcher halves, and established sampling points. The producer half of the field is managed the same as it was prior to study initiation while the researcher side of the field is managed with additional residual herbicide inputs as needed. At each sampling point, weed counts were taken before preplant weed control, before the first postemergence (POST) application, 2 weeks after the last POST application, and before cotton defoliation. Weed populations were recorded at each sampling point and totals on the two sides were compared to determine if the additional modes of action impacted weed species and numbers. Grower perceptions of weed composition and density differed from observed weed counts in the initial two years of this study.
