Assessment of the efficacy of seven plant extracts to inhibit strawberry bacterial leaf blight disease caused by Pantoea ananatis

Abstract This study investigates the antibacterial activity of the plant extracts in order to develop strategies for the prevention and management of Pantoea ananatis in strawberry. Seven plant extracts including eucalyptus, fenugreek, garlic, lantana, moringa, onion and pomegranate fruit peels were usedat concentrations of 40, 60, 80 and 100 mg/ml to test their efficacy against Pantoea ananatis in in vitro tests. The eucalyptus and pomegranate fruit peel treatments did not show inhibition of the growth of the pathogen. The garlic extract showed the strongest antibacterial activity against Pantoea ananatis , followed by lantana. Under field conditions, the effect of the ethanol extracts from garlic and lantana, applied by root dipping and foliar spraying were assessed. The antibacterial effect was larger when sprayed on the foliage. Disease severity was reduced by 56.0%. The results show that the vegetative growth and fruit quality of strawberry plants were significantly improved after foliar sprays. After foliar sprays with the garlic extract, the activities of several defense-related enzymes were significantly enhanced, including peroxidase, polyphenol oxidase, and β-1,3-glucanase. In this study, phenolic acids were identified in both garlic and Lantana ethanol extract, which could act as an active inhibitor of bcteria.