Response of Sweetpotato Cultivars toS-metolachlor Rate and Application Time

Abstract

Studies were conducted in 2008 and 2009 to determine the effect ofS-metolachlor rate and application time on sweetpotato cultivar injury and storage root shape under conditions of excessive moisture at the time of application.S-metolachlor at 1.1, 2.2, or 3.4 kg ai ha−1was applied immediately after transplanting or 2 wk after transplanting (WATP) to ‘Beauregard’, ‘Covington’, ‘DM02-180’, ‘Hatteras’, and ‘Murasaki-29’ sweetpotato. One and three d afterS-metolachlor application plots received 1.9 cm rainfall or irrigation.S-metolachlor applied immediately after transplanting resulted in increased sweetpotato stunting 4 and 12 WATP, decreased no. 1 and marketable sweetpotato yields, and decreased storage root length to width ratio compared with the nontreated check. Sweetpotato stunting, no. 1 and marketable yields, and storage root length to width ratio in treatments receivingS-metolachlor 2 WATP were similar to the nontreated check. In 2008, Covington and Hattaras stunting 12 WATP was greater at 2.2 and 3.4 kg ha−1(11 to 16%) than 1.1 kg ha−1(1 to 2%). In 2009,S-metolachlor at 3.4 kg ha−1was more injurious 4 WATP than 2.2 kg ha−1and 1.1 kg ha−1. While cultivar by treatment interactions did exist, injury, yield, and storage root length to width ratio trends were similar among all cultivars used in this study.