Isolation and Characterization of a Pseudomonas fluorescens Strain Suppressive to Bipolaris maydis

Strain PJ0210, identified as Pseudomonas fluorescens, inhibited Bipolaris maydis both in vitro. The absence of detectable inhibitory substances assayed by a variety of methods indicated nutrient competition as the operative component of antagonism. This was further supported by observations of reduced inhibition by addition of glucose both in vitro and in vivo. Strain PJ0210 was adaptecd to the phyllosphere showing good survivability and colonizing ability both inplant house and field trials. Disease suppression was generally correlated with population sizes of strain PJ0210. Population sizes in the field were lower than those recorded in the plant house with a concomitant reduction in disease suppressive ability, of strain PJ0210.