Phytotoxicity of Hesperozygis ringens (Benth.) Epling essential oil on Bidens pilosa L. and Paspalum notatum Flüggé

Essential oils (EO) are promising sources for the development of natural herbicides. This study evaluated the phytotoxic effects of the EO from Hesperozygis ringens and its major compound, pulegone, on Bidens pilosa (target plant) and Paspalum notatum (non-target plant). The EO extracted from the leaves was tested at different concentrations (0.001, 0.0025, 0.005, 0.01, and 0.02 % for in vitro propagules, and 1.0 % for adult plants in glass containers) in germination, early development, and leaf exposure bioassays. The experiments were conducted in a growth chamber under a completely randomized design. The higher concentrations (0.01 and 0.02 %) inhibited germination and impaired early growth, especially in B. pilosa, while pulegone alone was less toxic, indicating a synergistic effect among the EO constituents. In adult plants, the EO caused visible and anatomical leaf damage after 24 h, with minimal effects on P. notatum, suggesting selectivity. These results indicate the potential of H. ringens EO as a selective and sustainable natural herbicide.