Preliminary Study on the Antifungal Potential of Selected Plants as Botanical Fungicides Against Main Fungal Phytopathogens

Fungal diseases represent relevant constraints on global agricultural productivity, causing severe yield losses and deterioration of crop quality. The extensive use of chemical fungicides has produced environmental and health concerns due to their persistence, bioaccumulation, toxicity, and the increasing development of resistant fungal strains. To promote sustainable plant protection strategies, this study aimed to evaluate natural alternative products derived from botanical sources and agro-industrial wastes. Eighteen putative inhibiting products (PIPs), selected based on their availability as spontaneous plants or agro-industrial wastes, together with a commercial resistance inducer, were screened in in vitro assays against a collection of 31 phytopathogenic fungi. The inhibitory activity (IA) from the PIPs was evaluated, and statistical analyses were performed to identify the best performer. Several PIPs showed significant inhibitory activity against several fungal species, while others promoted fungal growth, highlighting the dual nature of the tested PIPs as potential bio-fungicides and growth-promoting agents for beneficial fungi. These findings highlight the value of plant-derived metabolites and agricultural waste valorization as promising sources for the development of sustainable botanical fungicides as well as support the transition toward eco-friendly crop protection strategies aligned with the European Green Deal objectives.