Microorganisms isolated from camellia blooms were evaluated for their ability to protect camellia flowers against ascospore infection by Ciborinia camelliae. Of the 277 isolates tested in camellia petal assays, Bacillus sp. LU1006, Bacillus subtilis LU1007, Pseudomonas sp. A3/B1, Pseudomonas marginalis LU1009, Pseudomonas fluorescens LU1004, Aureobasidium sp. Ch3F3, Cladosporium sp. LU172 and Cladosporium cladosporioides LU174 provided almost total protection against infection. However, when these isolates were suspended in water alone, or with either an organo-silicon surfactant (0.01% Break-Thru) or an ultraviolet protectant sticker-oil (Codacide), and sprayed onto 5-year-old potted Camellia japonica plants, they failed to reduce the incidence of camellia flower blight. Although these microorganisms protected individually sprayed petals from ascospore infection, they were unable to colonise petals on flowers sufficiently well to provide protection against camellia flower blight in field conditions.