Protecting peanut (Arachis hypogaea L.) from weed interference is important for optimizing yield in Ghana and other West African countries. Hand removal is the main approach for controlling weeds in this region of the world. Herbicides are an alternative to hand weeding. Information on the balance between herbicides and hand labor required to control weeds is limited. To address this, research was conducted to determine weed biomass, peanut yield, time required to remove weeds by hand and apply herbicides, and financial return when metolachlor was applied immediately after seeding (preemergence), imazethapyr was applied 4 weeks after seeding (postemergence), and both herbicides were applied either with or without hand weeding. Controls without weed management and hand removal of weeds without herbicides were included. Weed biomass was the lowest and peanut yield the highest when herbicides and hand weeding were included and when hand weeding was performed twice without herbicides. Herbicides were only less effective than combinations of herbicides and hand weeding. For weed management approaches that resulted in the greatest financial return, the time required for weeding was reduced from 44.5 workdays/ha for hand weeding twice to 14.1, 17.5, and 16.0 workdays/ha for preemergence herbicide plus hand weeding, postemergence herbicide plus hand weeding, and both herbicide timings plus hand weeding, respectively. These results indicate that the combination of preemergence and postemergence herbicides and the combination of herbicide and hand weeding protect peanut yield as well as hand weeding twice. Although herbicides resulted in less labor allocated for weed management, proper stewardship of herbicide use is needed to protect farm workers and decrease potential negative impact on the environment and reduce risk from herbicide residues in peanut-based foods to consumers.
Arthur et al. (Tue,) studied this question.