Effect of Thyme Essential Oil (Thymus vulgaris L.) on the Growth of Soil-Borne Fungal Pathogens

Abstract

Pests and diseases cause significant losses in agricultural production across both extensive and intensive systems. Within the latter, soil-borne fungal pathogens are particularly prominent, with control primarily relying on chemical methods. In intensive production, soil and substrate disinfection was, until recently, conducted using methyl bromide. Given the regulations against this biocide and the search for sustainable management strategies, this study proposes the use of Thymus vulgaris (thyme) essential oil (EO) for the control of three soil-borne fungal pathogens. The objective of this work was to evaluate the effect of thyme essential oil on the growth and development of Fusarium solani, Phytophthora capsici, and Rhizoctonia solani. To this end, the effect of different EO concentrations (50, 100, 150, 200, 250, and 300 ppm) on the colony growth of each individual pathogen was evaluated under in vitro conditions. Daily measurements of mycelial growth were taken until day 8, when the control groups reached full coverage of the Petri dishes. Both fungistatic and fungicidal effects were observed in all cases, albeit at different concentrations. Total inhibition was achieved at 250 ppm for F. solani, 200 ppm for R. solani, and 100 ppm for P. capsici. These results indicate that thyme EO could serve as an alternative for managing soil-borne fungal pathogens. Furthermore, the need for further in vivo research is emphasized to determine the efficacy of the EO under field conditions.