Ecofriendly management of post-harvest bacterial soft rot of potato caused by Pectobacterium carotovorum using different botanicals

Abstract

Bacterial soft rot caused by Erwinia carotovora is a major bacterial disease infecting almost all vegetable species having fleshy storage organs including potato. Management of post-harvest bacterial soft rot by chemicals has not proven practical and use of antibiotics can lead to severe health issues. During present study attempts were made to use aqueous plant extracts for the management of this disease. Aqueous extracts of 14 plant species, most of them belonging to the temperate ecology, were evaluated against the pathogen in vitro. Among them Syzygium aromaticum and Salix albaproved highly effective against the pathogen. Azadirachta indica, Urtica dioica, Xanthium sp., Cupressus torulosa and Morus alba also inhibited the growth of pathogen in vitro. Pinus sp, Allium sativum, Artemisia annua, Juglans regia showed moderate inhibition while aqueous plant extracts of Plantago major and Mentha arvensis were least effective. Syzygium aromaticum, Salix alba and Azadirachta indica which proved effective against the growth of test pathogen in-vitro, were also evaluated on potato tubers inoculated with the pathogen at different times i.e 12 hours prior to, simultaneously and 12 hours after the inoculation of the pathogen. Among these extracts, Syzygium aromaticum showed highest control of disease followed by Salix alba and Azadirachta indica in reducing the severity of disease recorded up to 6 days of storage. Best results were obtained with treatments given 12 hours prior to and at the time of inoculation of the pathogen.