Weed Management Strategies in Medicinal and Aromatic Plants: A Comprehensive Review

Medicinal and aromatic plants (MAPs) constitute a high-value agricultural sector due to their extensive use in pharmaceutical, cosmetic, food, and traditional medicine industries. However, many MAP species exhibit slow early growth, limited canopy development, and low competitive ability, making them particularly vulnerable to weed pressure. Weed infestation not only reduces biomass and yield but also poses serious quality and safety concerns by increasing contamination risks, altering secondary metabolite composition, and complicating harvesting and post-harvest processing. Of particular importance, weeds are the primary sources of pyrrolizidine alkaloids (PAs), toxic secondary metabolites that may contaminate MAP raw materials through co-harvesting and physical admixture. These challenges are further exacerbated by strict residue regulations, a limited number of registered herbicides, and the high susceptibility of many MAP species to herbicide-induced phytotoxicity. This review synthesizes current knowledge on weed management strategies in MAP production systems, with a focus on sustainability, product quality, and safety. Preventive and cultural practices, including crop rotation, optimized planting density, competitive cropping systems, sanitation measures, and cover crop use, are discussed as foundational approaches for reducing weed pressure. Mechanical and physical control methods, such as inter-row cultivation, manual weeding, flame and steam treatments, and precision mechanical techniques, are evaluated alongside mulching strategies using organic, synthetic, and biodegradable materials. The role of chemical weed control is critically assessed within the context of regulatory constraints, residue safety, and the need for integration with non-chemical approaches. Emerging alternatives, including allelopathic cover crops, biological control agents, weed seed bank management, and precision agriculture technologies, are also reviewed. Overall, this review highlights the necessity of integrated weed management strategies tailored to MAP biology, production scale, and regulatory frameworks. Future research priorities include defining critical weed-free periods, developing labor-efficient non-chemical control methods, and clarifying the relationships between weed management practices, secondary metabolite quality, and toxic contamination risks to support safe and economically sustainable MAP production.