Aromatic crops as resources for new sustainable bioherbicides: Allelopathic activity of industrial products, by-products and wastes

Weeds account for up to 34 % of annual agricultural losses. The predominant management strategy is the use of synthetic herbicides, the most applied pesticides worldwide, which pose serious environmental and health risks. Therefore, sustainable and safe alternatives, such as bioherbicides, are urgently needed. Aromatic crops and their industrial by-products are a rich source of bioactive compounds with phytotoxic activity and high potential for bioherbicide development. This review systematically integrates 89 scientific studies retrieved from Scopus and Web of Science databases (search date: August 3, 2025), using the keywords “aromatic crop AND (extract OR essential oil OR by-product OR waste) AND (bioherbicide OR allelopathy)”, in order to ensure comprehensive coverage of the phytotoxic effects of essential oils (EOs), plant extracts, hydrosols and solid residues on weeds and non-target crops. These articles were published between 1978 and 2025 in a total of 56 different journals. EOs exhibit strong phytotoxicity against diverse weed species, largely due to compounds such as carvacrol, thymol, 1,8-cineole, camphor, linalool, menthol, pinene, terpinen-4-ol and thujone. Similarly, aqueous, ethanolic, and methanolic extracts show herbicidal potential through bioactives including artemisinin, coumarin, 2-cyclopenten-1-one, limonene, N-octanoyl tyramine and tayunin. Industrial by-products, such as hydrolates, wastewaters and distilled straws, also demonstrate phytotoxic capacity linked to molecules like danshensu, carnosic acid, carnosol and lysophosphatidylcholine. The effectiveness of these natural resources can be enhanced through advanced delivery methods, including microencapsulation, nanoemulsions, and oil-loaded biochar. However, many of these products also display phytotoxicity toward non-target crops, underscoring the importance of evaluating their selectivity and potential agronomic risks before field application. In conclusion, aromatic crops represent a promising source of effective bioherbicides, but further research is required to clarify the mechanisms of action of their bioactive compounds, evaluate their field performance, and determine their impacts on non-target crops. • Review of 89 studies on aromatic crop derivatives used as bioherbicides. • Essential oils, extracts and by-products show strong phytotoxic activity. • Carvacrol, thymol, cineole, linalool, menthol and limonene act herbicidally. • Some derivatives affect non-target crops, highlighting selectivity needs. • Formulations like microencapsulation or nanoemulsions improve efficacy.