The invention provides extracts and preparations based on the species Tulbaghia violacea (Harv.) (wild garlic), which elicits a significant antimicrobial, preferably antifungal activity in vitro and in vivo, even under field and glasshouse conditions. Moreover, these extracts deriving from the soil parts as well as of the aerial parts of the plant elicit a significant bio-stimulatory activity, expressed, above all, by an increased growth metabolism supporting seed growth. Furthermore, combined extracts or preparations from Tulbaghia violacea and species of the genus Agapanthus show a higher antifungal and bio-stimulatory efficacy as compared to the extracts or preparations of the single species, indicating that synergism is participated in the involved biological processes.