Effect of applications of oregano and thyme essential oils in Glycine max seeds against bacterial blight caused by Pseudomonas savastanoi

Abstract Pseudomonas savastanoi is the causal agent of bacterial blight in Glycine max. One of the routes of transmission of this pathogen is through seeds. Therefore, treating seeds with compounds that reduce bacterial proliferation represents an appealing solution to prevent production losses. Currently, studies focus on the search for natural products derived from aromatic plants with antimicrobial properties as effective and environmentally prudent alternatives. This study aims to further investigate the efficacy of oregano and thyme essential oils in treating seeds against this pathogen. In a previous study, greenhouse trials were conducted using thyme oil. In this research, greenhouse trials were performed using oregano essential oil, and field trials were conducted for both oils. In both oils, a non-phytotoxic concentration of 0.89 mg/ml for oregano essential oil and 1.76 mg/ml for thyme essential oil was determined. Both essential oils reduced the incidence and severity of the disease and the number of cells in the seeds, showing that thyme oil has a better effect than oregano under controlled conditions and in the field. The results obtained in this study demonstrate the efficiency of natural products in reducing pathogenic bacteria in seeds, representing a new natural alternative to control these microorganisms.