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.