Efficacy and Selectivity of S-Metolachlor for Weed Control in Sugar Beet (Beta vulgarisL.), Gezira State, Sudan

Abstract

Sugar Beet (Beta vulgaris L.) is considered as the second most important crop in the world after sugar cane in sugar production. Weed competition is considered one of the major constrains to achieve maximum sugar beet yield. The objective of this study was to evaluate the efficacy and selectivity of the herbicide S-metolachlor for weed control and their effect on sugar beet growth and yield. A field experiment was conducted during 2017/18 winter season at the experimental farm, Faculty of agricultural Sciences Gezira University, Sudan. The herbicide S-metolachlor (Dual Gold 96% EC) at two rates (1.92 and 2.4 kg a.i./ha) was applied as per-sowing, two weeks before planting and irrigated immediately after application. Hand weeded and un-wedded treatments were added as controls. The treatments were arranged in a randomized complete block design in 4 replicates. Data were subjected to analysis of variance (ANOVA) procedure (P ≤ 0.05). Significant means were separated using Duncan's Multiple Range test (DMRT). The herbicide treatments S-metolachlor at the rate of 1.92 and 2.4 kg a.i./ha exhibited slight phytotoxicity on sugar beet plant. S-metolachlor at the two rates tested gave 77-79.5% grass weed control and 52-53% broadleaved weed control. The herbicide treatments significantly increased the root length, root diameter and root weight of sugar beet as compared to un-weeded check. S-metolachlor at the two rates tested gave significantly high root weight compared to un-weeded check. The herbicide treatments increased the gross sugar yield. S-metolachlor at 1.92 and 2.4 kg a.i./ha gave significantly high gross sugar yield (0.95 – 1.22 ton/ha) compared to 0.15 kg/ha gross sugar yield of the un-weeded control. It could be concluded that S-metolachlor at 1.92 kg a.i./ha could be used for weed control in sugar beet to be applied and immediately irrigated two weeks before sowing of sugar beet. Further studies are needed to confirm their safety and inclusion in a management program.