Using Essential Oils to Protect Peaches from Post-Harvest Rot Caused by Rhizopus Species

Abstract

Rhizopus is an important post-harvest pathogen that causes rot in fruits and vegetables. During 2022, a considerable incidence of post-harvest rot of peaches was observed in local markets in Bahawalpur, Pakistan. The symptoms appeared as whiskery moldy growth on the surface of the fruit. The pathogen was isolated and identified as Rhizopus species based on morphological features. Under the microscope, sporangiospores of Rhizopus were observed as light brown in color. The colony was very fast-growing and spreading. The color of Rhizopus mycelium was greyish. The pathogenicity was confirmed to satisfy Koch’s postulates. The pathogen caused lesions on the surface of peach fruit. The current study also assessed the antifungal effects of essential oils on the growth of Rhizopus. Two essential oils were used: clove oil and cinnamon oil at concentrations of 0%, 25%, 50%, 75%, and 100%, respectively. The disease lesion with a diameter of 1.6 cm was treated with clove oil, 1.3 cm with 100% concentrated cinnamon oil, and 2.4 cm with the control (inoculated with Rhizopus). Cinnamon oil gave the maximum inhibition of Rhizopus on peach fruit compared to clove oil. The loss in fruit weight was minimum (2 g) in cinnamon-treated fruit compared to clove oil (3 g), control (2 g), and the infected one without any treatment (7 g). In conclusion, the study provides important information about Rhizopus as a significant post-harvest pathogen causing rot in fruits and vegetables, with a specific focus on peach fruit in Bahawalpur, Pakistan. The findings suggest that cinnamon oil could be a potential natural antifungal agent to mitigate post-harvest rot caused by the fungus in peaches.