48th TWC, Tob. Work. Conf., 2018, abstr. 22

Evaluation of S-metolachlor for use in flue-cured tobacco production

North Carolina State University, Raleigh NC USA

With limited herbicide options and a growing concern to herbicide-resistant weeds, there is a strong need for additional chemical weed control materials in tobacco. S-metolachlor is labeled for use in a variety of agronomic and horticultural crops in the United States, and for use in some tobacco growing countries outside of the United States. S-metolachlor has been shown to be effective in providing residual weed control of common weed species such as nutsedge, Palmer amaranth, and various grass species. The objectives of this research are to i.) evaluate crop and weed response to herbicide programs with and without S-metolachlor, ii.) evaluate tobacco tolerance to S-metolachlor at different rates (1,069 g ai/ha and 2,138 g ai/ha) and application methods (pre-transplant incorporated (PTI) and pre-transplant (PRE-T), and iii.) to generate efficacy and pesticide residue data to support a federal label for U.S. tobacco production. Regardless of rate, severe stunting and plant death was observed with PTI applications where excessive precipitation followed at one location (50-75% of non-treated check). Stunting was minimal (<10%) in all PRE-T treatments across all locations. Treatments comprised of S-metolachlor and other herbicides resulted in better weed suppression than treatments with S-metolachlor as a stand-alone material. Preliminary results indicate that S-metolachlor may be a suitable candidate for use in tobacco production. (Reprinted with permission)