Bio Control Potential of Pseudomonas fluorescens against Coleus Root Rot Disease

S Vanitha R Ramjegathesh

doi:10.4172/2157-7471.1000216

Abstract

Ten different strains of Pseudomonas fluorescens were isolated from coleus rhizosphere except the pf1 strain and identified by biochemical tests. These strains were screened against Macrophomina phaseolina (Tassi) Goid, the causal organism of coleus root rot. The results revealed that Pf1 strains recorded maximum inhibition of mycelial growth against control. The mechanism of Pseudomonas strains namely the iron-chelating agent (siderophore), volatiles (HCN) and antibiotic (Fluorescein and pyocyanin) production tests were studied and reacted for siderophore, antibiotic and HCN production. The talc-based formulation of Pf1 and CPF1 was prepared and the bio-efficacy was tested under greenhouse conditions. The stem cutting and soil application of the talc-based formulation of Pf1 significantly reduced the root rot incidence and increased shoot and tuber length also.

Highlights

Coleus (Coleus forskohlii Briq.) is cultivated mainly for their medicinal values in India
Fluorescent pseudomonads are non-pathogenic rhizobacteria which suppress the soil-borne pathogens through rhizosphere colonization, antibiosis, iron chelation by siderophore production and induced systemic resistance (ISR)
Phaseolina was isolated from coleus plants showing typical root rot symptoms and pure cultures of the pathogen were obtained by the single hyphal tip method [6]

Summary

Introduction

Coleus (Coleus forskohlii Briq.) is cultivated mainly for their medicinal values in India. Among the PGPR, fluorescent pseudomonads are the most exploited bacteria for biological control of soil-borne and foliar plant pathogens. In the past three decades, numerous strains of fluorescent pseudomonads have been isolated from the rhizosphere soil and plant roots by several workers and their biocontrol activity against soil-borne and foliar pathogens were reported [3].

Results

Conclusion