Wesley J. Everman1, S. B. Clewis1, D. L. Jordan1, J. 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. 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. Economic analysis was conducted on the RR cotton systems to determine cost of weed control and return on investment.
