RESIDUAL WEED CONTROL IN PEANUT WITH CADRE, STRONGARM, VALOR, AND SPARTAN: A MULTISTATE AND MULTIYEAR SUMMARY T.L. Grey, D.C. Bridges, E.F. Eastin, E.P. Prostko, and W.K. Vencill - Univ. Georgia W.C. Johnson, Jr.- USDA-ARS B.J. Brecke, G.E. MacDonald, and J.A. Tredaway - Univ. Florida J.W. Everest and G.R. Wehtje - Auburn Univ. J.W. Wilcut - North Carolina State Univ. Introduction Peanut development and maturity require a long growing season and thus, the residual activity of herbicides applied early season may not provide effective season-long weed control if no additional herbicides are applied. Therefore, residual weed control is an important part of peanut production. This is illustrated by the fact that paraquat is often tank-mixed with Basagran EPOT, but it is rarely used alone, that is in the absence of other weed control treatments because of the lack of residual control. During the 1980's and 1990's, the development and introduction of PPI, PRE, and POST herbicides emphasized the control of broadleaf, nutsedge, and grass species. Lack of extended residual activity, variation in weed control spectrum, rotational restrictions, and cost are factors in herbicide selection. Until recently, these factors have limited the domination of any one particular herbicide in the Southeastern United States peanut market. Reviews of the herbicide options for peanut weed control were conducted and published in 1994 and However, since then the residual herbicides available for peanut weed control have changed: Cadre (imazapic) was registered in 1996 for POST application; Strongarm (diclosulam) was registered for PPI and PRE application in 2000; Valor (flumioxazin) was registered for PRE application in 2001; and Spartan (sulfentrazone) is currently under registration review. This review was conducted to summarize current and future weed control options for peanut producers, extension, and the agchem industry. Weed control data from research conducted from by The University of Georgia, University of Florida, and Auburn University were compiled, reviewed, summarized, and presented here. Materials & Methods In 2001, Georgia scientists compiled data from over 100 experiments to conduct this review. The review includes 23 treatments using PPI, PRE, EPOST, and POST treatments of Cadre, Strongarm, Valor, Spartan, and a standard, paraquat + Basagran (Table 1). Paraquat and paraquat- tank mixtures were applied to 110% of the 1998 Georgia peanut crop (unpublished data). Therefore, paraquat + Basagran was chosen as the standard treatment. Twelve regionally important weeds were selected based on a county extension survey conducted in Georgia. Weed control was averaged across tests and years to report average weed control, standard deviation, and number of tests for each of the 12 weeds when each herbicide was applied alone and in combination with paraquat + Basagran. Results & Discussion All weed control ratings reflect mid-season weed control (July) except for Florida beggarweed, which are from late-season ratings (September). For weed control results by species when herbicides were applied alone refer to Table 1. Sicklepod, Florida beggarweed, and purple and yellow nutsedge are considered primary common and troublesome weeds in southeastern peanut fields. Sicklepod control with Cadre alone was good; fair with paraquat + Basagran; and, poor with other herbicides alone. Florida beggarweed control was good-excellent with Valor; fair- good with Strongarm; fair with Cadre and Spartan; and poor-fair with paraquat + Basagran. Purple nutsedge control was excellent with Cadre; poor-fair with Spartan; and poor with other herbicides applied alone. Yellow nutsedge control was excellent with Cadre and Spartan; good with Strongarm; and poor with Valor and paraquat + Basagran. Control of other species varied by treatment when herbicides were applied alone. When herbicides were applied in combination with paraquat + Basagran, weed control generally improved (Table 2). Conclusions The following is noteworthy: only Cadre controlled sicklepod; only Valor controlled Florida beggarweed greater than 90%; Cadre controlled purple and yellow nutsedge greater than 90%; Spartan controlled yellow nutsedge greater than 84%; all herbicides gave good-excellent morningglory control; Strongarm provided nearly 90% bristly starbur control at all rates and application timings. Tables 3 and 4 show proposed weed response recommendations for these herbicides. Acknowledgements The authors appreciate the support of their respective institutions and BASF, Dow AgroScience, FMC, Syngenta, and Valent for their support of this research. Table 4. Weed Control Summary: With paraquat + Basagran Table 3.Weed Control Summary: Applied Alone Excellent >89%; Good 79-91; Fair 69-81; Poor <69. Cadre 1.44 oz/ac POST; Strongarm 0.45 oz/ac PPI; Valor 3.0 oz/ac PRE; Spartan 8.0 oz/ac PRE paraquat + Basagran, variable.