Abstract
A field experiment was conducted at the Akwa Ibom State University Teaching and Research Farm, Obio Akpa, Oruk Anam, Akwa Ibom State in the 2021 and 2022 cropping seasons, to evaluate the efficacy of herbicides and cassava varieties on weed flora, density, biomass and yield of cassava (Manihot esculenta Crantz) in Akwa Ibom State. The experiment was fitted into a split-split plot arrangement and a randomized complete block design, replicated three times was used. The main treatments were three cassava cultivars-TMS 980505, TME 419 and TMS-981632, sub treatments were four types of herbicides-pendimethalin, butachlor, diuron, and primextra. The sub-sub treatments were five rates of herbicide application- 0, 1.0, 2.0, 3.0 and 4.0 kg a.i/ha. Data collected on weed flora, density, biomass, height at first branching and yield of cassava were subjected to analysis of variance. Results showed that weed density and biomass were significantly (p< 0.05) affected in both cropping seasons. Weed density, biomass and tuber yield decreased with increase in rate of application of herbicides. TMS 980505 had the highest yield of 32.89t/ha and 33.26t/ha in 2021 and 2022 respectively and the highest branching ability, as well as the ability to suppress weeds as reflected in the lowest weed density and biomass associated with this variety. Similar results were recorded among the herbicide types. Primextra gave the highest root yield, lowest weed density and biomass. In addition, Primextra was able to control both grasses and broad leaf weeds compared to other herbicides. Efficacy of the herbicides on weeds increased with increase in rates of application. Based on the findings, primextra at 2.0 kg a.i/ha and cassava variety TMS 980505 is recommended for increased cassava production in the study area.