Integration of Rhizobacterial Isolates and Airone Chemical for Effective Management of Bacterial Wilt in Cucumber (Cucumis sativus)

Abstract

The present study aimed to evaluate the efficacy of integrated disease management strategies against bacterial wilt, caused by Erwinia tracheiphila in cucumber (Cucumis sativus) within a controlled greenhouse environment. A total of 56 E. tracheiphila were recovered from the symptomatic cucumber plants among which 13 were tested highly virulent. Among six rhizobacterial isolates; Pseudomonas flurescens-3 (Pf-3), Pseudomonas putida-5 (Pu-5), Pseudomonas stutzeri-2 (Ps-2), Bacillus subtilis-1 (Bs-1), Bacillus safensis-2 (Bs-2), and Pseudomonas stutzeri-1 (Ps-1), tested in vitro using dual culture technique against extremely virulent strain of E. tracheiphila revealed Pf-3, Pu-5 and Bs-1 significantly reduced its growth. Two separate experiments were performed to investigate the synergistic effects of these PGPRs in combination with Airone chemical (active ingredients; Copper Oxychloride + Copper Hydroxide 20%SC by Swat Agro Chemicals, Pakistan) on disease severity and overall plant growth. In the first experiment, eight treatments were tested in a complete randomized design (CRD) with eight replications, focusing on the combination of Pf-3, Pu-5 and Bs-1. Results revealed that the combined application of Pf-3 and Pu-5 significantly outperformed other treatments, exhibiting substantial improvements in key growth parameters; vine length, number of leaves and branches per plant, and a remarkable reduction in disease severity compared to positive and negative controls. In the second experiment, Pf-3, Pu-5 and Bs-1 and Airone chemical were employed in seed and soil treatments to confer resistance to E. tracheiphila and suppress bacterial wilt. The treatment involving P.u-5 and Bs-1, along with a foliar spray of Airone, recorded the lowest disease severity and an increase in plant growth compared to the positive control. These findings suggest that the synergistic application of PGPR and Airone chemical holds promise for integrated disease management in cucumber, providing effective control of bacterial wilt while promoting plant growth. Moreover, the environmentally friendly nature of rhizobacterial-based formulations underscores their potential as safe alternatives for controlling soil-borne plant pathogens without adverse effects on human health or the environment