|Koger Iii, Clifford|
Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2004
Publication Date: 1/26/2004
Citation: Everman, W.J., Burke, I.C., Wilcut, J.W., Miller, D., Price, A.J., Koger III, C.H., Porterfield, D. 2004. Weed control, crop tolerance, and yield with touchdown, dual magnum caparol, and envoke weed management systems. In: Proceedings of Southern Weed Science Society. p. 258.
Technical Abstract: Experiments were conducted in North Carolina in 2002 and Alabama, Louisiana, Mississippi, and North Carolina in 2003 to evaluate weed control, crop tolerance, and yield potential with a total postemergence (POST) weed management system that included combinations of residual and transgenic herbicides in Roundup-Ready® cotton. The transgenic cotton varieties included Fibermax 989 RR/BG, Deltapine 458 BR, and Stoneville 4793 RR. The experimental design was a randomized complete block with a factorial treatment arrangement of early-postemergence (EPOST), POST, post-directed (PDS), and late post-directed (LAYBY) options with 3 to 4 replications, depending on locations. The EPOST treatments included 1) Touchdown alone at 0.75 lb ae/A or 2) a tank mixture of Touchdown + Dual Magnum at 1.0 lb ai/A. The POST/PDS treatments included 1) No POST, 2) Envoke alone at 0.0048 lb ai/A POST or 3) PDS, 4) Envoke plus MSMA at 2.0 lb ai/A PDS, or 5) Envoke plus Touchdown at 0.75 lb ae/A PDS. The LAYBY treatments included 1) NO LAYBY or 2) Caparol at 1.0 lb ai/A plus MSMA at 2.0 lb ai/A plus Induce at 0.25% v/v. Early season cotton injury and discoloration was minimal (<1%) with all treatments, mid- and late-season injury was <2% except for Envoke POST which injured cotton 9 to 11%. Envoke injury was transitory and not visually apparent at late season evaluations. Cotton injury was minimal with all treatments applied PDS. POST and PDS herbicide applications provided >80% control of sicklepod, smooth amaranth, and entireleaf and pitted morningglory. Envoke POST and PDS applied alone or in combination with Touchdown or MSMA averaged over EPOST and LAYBY treatments increased sicklepod control 25 to 30% points, smooth pigweed control 23% points, entireleaf morninglory, and pitted morningglory 19-30% points compared to EPOST only systems. Envoke PDS/POST provides limited suppression (<7 days) of annual grasses. Touchdown plus Envoke increased control of goosegrass > 20 percentage points, barnyardgrass 30 percentage points, and large crabgrass 20 percentage points. Envoke did not appear to antagonize Touchdown control of these annual grasses. The addition of a LAYBY treatment increased control of all weeds 11 to 21% percentage points. Envoke + Touchdown PDS had the highest yield of 1060 lb/A regardless of EPOST or LAYBY treatment. Cotton lint yield increased 160 to 400 lb/A with the addition of POST/PDS treatments compared to EPOST only systems. The addition of Caparol + MSMA LAYBY increased cotton lint yield by 200 lb/A compared to systems without a LAYBY. These data indicate the spectrum and level of weed control was broader with Envoke in combination with Touchdown PDS than with other POST/PDS treatments. Yield and weed control data indicate a two-pass system will often work, however a three-pass system will always work.