A Pseudomonas-based bio-formulation to control bacterial blight of pomegranate caused by Xanthomonas axonopodis pv. punicae

Abstract

Plant growth-promoting bacteria (PGPB) have emerged as sustainable tool for managing plant diseases. This study investigates the potential of a Pseudomonas-based biocontrol agent to manage bacterial blight (BB) in pomegranate. This major disease is caused by Xanthomonas axonopodis pv. punicae (Xap) and it is traditionally controlled with antibiotics. Of the 151 bacterial isolates obtained from the pomegranate rhizosphere, three (UHSPS15A, UHSPS33, and UHSPS54) demonstrated the strongest inhibitory effects against Xap in vitro, and their identification as Pseudomonas was confirmed through DNA analysis. Greenhouse trials with Xap-inoculated plants revealed that preventive application of each of the three isolates was more effective than curative, with UHSPS15A providing the highest protection. A talc-based formulation was developed using UHSPS15A. After evaluating its stability and efficacy in greenhouse Xap-inoculated pomegranates plants, open-fields trials indicated that among the three different treatment modes tested, the combined soil and foliar application achieved the highest disease protection and fruit yield, topping the standard antibiotic control. These findings recommend that integrating Pseudomonas-based bio-formulations into disease management strategies could significantly reduce reliance on synthetic chemicals, offering a sustainable alternative for controlling BB in pomegranate.