Biological Control of Botrytis cinerea on Roses with Epiphytic Microorganisms. J. C. Redmond, Department of Plant Pathology, University of California, Davis 95616. J. J. Marois, and J. D. MacDonald. Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 71:799-802. Accepted for publication 10 April 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0799.

Fungi and bacteria isolated from rose petals were evaluated for their potential as biological control agents of Botrytis blight, a serious disease of greenhouse-grown roses. Preliminary evaluations identified four microorganisms with the ability to reduce the number of lesions caused by Botrytis cinerea on rose. Biological control by these antagonists, Exophiala jeanselmei, Cryptococcus albidus, an Erwinia sp., and a coryneform bacterium, was demonstrated by applying them to cut roses 1 day before inoculation with a suspension of 1,000 conidia of B. cinerea per milliliter. The most effective antagonist was a yeast, E. jeanselmei, which reduced the number of lesions by 63%. This level of control was not significantly different from control achieved by the fungicide iprodione (74%).