Biological Control of Cyclamen Soilborne Diseases by Serratia marcescens Strain B2.

Cyclamen plants were treated with a highly chitinolytic bacterium, Serratia marcescens strain B2, and then challenge inoculated with Rhizoctonia solani sclerotia or Fusarium oxysporum f. sp. cyclaminis conidia. The bacterium suppressed these fungal diseases of cyclamen plants, especially the damping off caused by R. solani, in a greenhouse. Strain B2 survived at approximately 10⁶ to 10⁷ CFU/g in soil for 4 months after the initial application under greenhouse conditions. Chitinolytic enzymes and antifungal low-molecular-weight compounds were present in filtrates of S. marcescens B2, which suppressed germination of R. solani sclerotia in vitro.