Interactions Between the Biological Control Agent<i>Pseudomonas fluorescens</i>A506 and<i>Erwinia amylovora</i>in Pear Blossoms

Abstract

In the greenhouse, Pseudomonas fluorescens strain A506 effectively colonized the pistils of pear blossoms. P. fluorescens A506 significantly reduced colonization of pear pistils by Erwinia amylovora when the biological control agent was inoculated 72 h in advance of the pathogen, but not when it was coinoculated with E. amylovora. P. fluorescens A506 probably excluded E. amylovora by preemptively utilizing a growth limiting resource required by the pathogen. A506 also colonized the nectaries of pear blossoms, in which it maintained high populations for 60-72 h []