Efficiency of Essential Oils and Their Constituents in the Control of Geotrichum citri-aurantii and Penicillium digitatum of Oranges

Penicillium digitatum and Geotrichum citri-aurantii are fungi that cause green mold and sour rot, respectively, both of which are postharvest diseases responsible for economic losses in oranges. Concerns about environmental and human health regarding agrochemicals necessitate the investigation of effective disease control alternatives. This study aimed to investigate the in vitro effect of seven essential oils (EOs) on the mycelial growth of G. citri-aurantii and P. digitatum in orange, to identify the EOs with the highest antifungal activity, and to determine the minimal inhibitory concentration (MIC) of the selected EOs. Additionally, the chemical composition of two batches of EOs from the same plant species was analyzed using gas chromatography with mass spectrometry (GC-MS), and the results were compared. The antifungal activity of the mixture of the major constituents of each selected EO was evaluated. According to the results, oregano, cinnamon bark, clove basil, and rosemary pepper EOs exhibited the most promising outcomes in inhibiting G. citri-aurantii and P. digitatum, with MIC of 0.25-3.0 mu L. mL-1. Despite being extracted from the same plant species, the two EO batches showed different profiles of chemical constituents and proportions. Concerning the antifungal activity of the constituents, the mixture of the three major EO constituents displayed greater antifungal activity than the pure EO, with MIC of 0.25-1.00 mu L. mL-1, suggesting an interaction among the mixture components. Therefore, using a mixture of the major constituents of EO represents a promising alternative to chemical fungicides commonly used for controlling postharvest diseases in oranges.