Technical Abstract: Apple blossoms were sampled for indigenous epiphytic populations of culturable microorganisms during different stages of bloom at two orchards in or near Wenatchee, WA, and one in Corvallis, OR. Frequencies and population sizes of bacteria on stigmas of apple were lower at Wenatchee than Corvallis, where higher average relative humidity may have been more favorable for colonization. Bacteria from flowers in Corvallis were mainly Pseudomonads, whereas those from Wenatchee sites were diverse, composed of several other genera. At Wenatchee, yeast as well as bacteria were isolated from both stigmatic and hypanthial surfaces. Sampled blossoms were processed immediately to assess microbial populations, or after a 24-h incubation at 28°C, which broadened the range of detectable taxa evaluated for use in biological control. Identifications were based on FAME and rRNA-sequence analyses. Yeasts (or yeast-like organisms) were detected at frequencies similar to, or greater than, bacteria, particularly in the hypanthium. When isolates were tested for their capacity to suppress E. amylovora on stigmas of detached crab apple flowers, yeasts were not effective, but their adaptation to flowers and known osmotolerance may be advantageous for preempting the pathogen on the nectariferous hypanthium. Bacteria identified as Pantoea agglomerans were most effective in suppressing E. amylovora on stigmas, followed by isolates of Pseudomonas spp. Bacillus spp. and members of other diverse genera were generally poor performers.