Efficacy and selectivity of pendimethalin for weed control in sugar beet (Beta vulgaris L.), Gezira state, Sudan

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 as 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 Pendimethalin 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 Pendimethalin (Pendico50% EC) at two rates (3.6 and 4.8 kg a.i. ha-1) 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 procedure (P ≤ 0.05). Pendimethalin at the lower rate (3.6 kg a.i. ha-1) exhibited slight phytotoxicity on sugar beet plant. The herbicide at the lower rate gave 82% grass weed control and 56% 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. Pendimethalin at the two rates tested gave significantly high root weight compared to un-weeded check. The herbicide treatments increased the gross sugar yield. Pendimethalin at 3.6 and 4.8 kg a.i. ha-1 gave significantly high gross sugar yield (0.74 – 0.52 tonha-1) compared to 0.15 kgha-1 gross sugar yield of the un-weeded control. It could be concluded that Pendimethalin at 3.6 kg a.i. ha-1 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.