Agri-Food Waste as a Source of Active Ingredients for Plant-Protection Products

Can waste serve as a source of known or novel molecules for plant disease management? This review explores this question, which is closely linked to the necessity of mitigating the environmental impact of agriculture, specifically in terms of waste generation and greenhouse gas emissions. Furthermore, it addresses the increasing demand for safer, environmentally friendly alternatives to ensure sustainable plant production and protection. To satisfy these needs, research efforts over the past few decades have primarily focused on biocontrol strategies, with the valorization of waste being addressed only recently. Different approaches have been applied for extracting bioactive molecules from waste, ranging from green chemistry to microbial fermentation. We discuss secondary metabolites, elicitors, and biosurfactants obtained chemically and from fermentation. Microorganisms growing on waste can produce biomass or spores [bioactive ingredients of plant-protection products (PPPs)] and facilitate the extraction of active compounds. Although the production of spores on waste material is now well-established on an industrial scale, the extraction of biologicals from waste and/or their production through fermentation are still at the experimental stage. The growing knowledge on the bioactivity of agri-food waste-derived molecules against phytopathogens is paving the way for the development of new PPPs suitable for integrated pest management. The waste-based PPPs pipeline described here shows strong potential to generate both established and novel, regulation-compliant compounds without sacrificing disease-control efficacy.