Circular Valorization of Laurel and Myrtle Pruning Residues: Chemical Profiling, Phytotoxicity, and Ecotoxicological Assessment of Essential Oils for Sustainable Weed Management

The valorization of medicinal and aromatic plant by-products represents a sustainable strategy to recover bioactive compounds and reduce agricultural waste. In this study, pruning residues of Laurus nobilis L. and Myrtus communis L. were investigated as sources of essential oils (EOs) for bio-based weed management. Leaves and young stems were subjected to anatomical, micromorphological, and histochemical analyses to ascertain that active secretory structures were maintained. EOs were then obtained by steam distillation and characterized by GC-FID and GC-MS. Phytotoxicity was evaluated on two crop species, Hordeum vulgare L. and Raphanus sativus L., and two weed species, Lolium multiflorum Lam. and Sinapis alba L.; ecotoxicity was assessed using Artemia salina and Daphnia magna. The EOs were mainly composed of oxygenated monoterpenes, with 1,8-cineole as the dominant constituent in both oils. Phytotoxicity was species- and concentration-dependent, with M. communis EO showing the strongest inhibition, particularly against S. alba. Ecotoxicological assays revealed limited toxicity toward A. salina, but concentration-dependent immobilization of D. magna. Overall, these findings support the circular valorization of laurel and myrtle pruning residues as sources of bioactive EOs while highlighting the need for further formulation, selectivity, and environmental safety studies before agricultural application.