Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2011
Publication Date: August 28, 2011
Citation: White Jr, P.M., Potter, T.L. 2011. Metolachlor fate in regionally adopted cropping systems of the SE United States. American Chemical Society Fall 2011 National Meeting and Exposition, August 28 - September 2, 2011, Denver, Colorodo. CDROM. Technical Abstract: Effective assessment of the risks of pesticide use and agronomic efficacy require data that accurately describes environmental fate under actual use conditions. This was demonstrated for the herbicide metolachlor (2-chloro-N-(6-ethyl-o-tolyl)-N-[(1RS)-2-methoxy-1-methylethyl]acetamide) in investigations focused on cropping systems in the SE U.S.A. Results showed that management practices like cover crops, co-application of fungicides, changes in herbicide formulation from liquid to granular, and gypsum may alter fate. During a field study in Southern Florida, we found metolachlor and ethane sulfonic acid levels were 16 and 2.4X lower in groundwater under cover crops. In combined field and laboratory studies in the Coastal Plain of Georgia, application of chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile) and gypsum increased metolachlor DT50 by 2X and 1.5X, respectively. Granular metolachlor provided superior weed control but increases in soil persistence increase the potential for herbicide crop injury. Findings serve as a case-study and guide to investigations that are needed to make crop-specific management decisions.