Efficacy Trial of Chromolaena odorata and Coconut Vinegar as an Alternative Herbicide

This study evaluated the herbicidal efficacy of aqueous extracts from different parts of Chromolaena odorata (L.) enhanced with coconut vinegar for the control of common weeds under field conditions. Specifically, the study aimed to determine which plant part (leaves, roots, or stems) exhibited the greatest weed control efficacy compared with a positive control (sterile distilled water) and a negative control (glyphosate). The experiment was conducted using a Randomized Complete Block Design (RCBD) with five treatments and three replications. The treatments consisted of T1 – Sterile Distilled Water (positive control), T2 – C. odorata leaves + coconut vinegar + sterile distilled water, T3 – C. odorata roots + coconut vinegar + sterile distilled water, T4 – C. odorata stems + coconut vinegar + sterile distilled water, and T5 – Glyphosate (negative control). Results showed that the C. odorata-based formulations significantly suppressed weed growth compared with the untreated control. Seven days after application, Treatment 2 recorded the highest weed control rating among the botanical treatments (7.33 ± 0.58), followed by Treatment 4 (7.00 ± 1.00) and Treatment 3 (6.67 ± 1.15), while glyphosate achieved a mean rating of 8.00 ± 0.00. Fourteen days after application, weed control ratings declined for the botanical treatments, with Treatment 2 recording 5.33 ± 0.58, Treatment 4 recording 5.00 ± 1.00, and Treatment 3 recording 4.67 ± 0.58, whereas glyphosate achieved complete weed control (10.00 ± 0.00). Analysis of variance (ANOVA) revealed highly significant differences among treatments at both evaluation periods (p < 0.001). Tukey's Honestly Significant Difference (HSD) test indicated that all C. odorata-based treatments significantly outperformed the untreated control, while no significant differences were observed among the leaf, root, and stem extracts. However, glyphosate provided significantly greater weed control than the botanical formulations after 14 days. Among the weed species evaluated, Cleome rutidosperma was the most susceptible to the C. odorata extracts, whereas Physalis angulata was the least affected. The findings demonstrate that aqueous extracts of C. odorata enhanced with coconut vinegar possess promising herbicidal activity and can effectively suppress common weeds, particularly during the early stages of weed growth. Although their efficacy was lower than that of glyphosate over time, the comparable performance of the leaf, root, and stem extracts suggests that allelopathic compounds are distributed throughout the plant. These results highlight the potential of C. odorata as a sustainable botanical herbicide and provide a basis for further optimization of formulation, concentration, and application strategies for integrated weed management.