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POSTERS: Biological control

Identification of beneficial Pseudomonas strains for the biocontrol of Botrytis cinerea in floriculture crops
Kaylee South - The Ohio State University. Michelle Jones- The Ohio State University, Francesca Peduto Hand- The Ohio State University

Botrytis cinerea is one of the most common fungal pathogens found in the greenhouse industry worldwide. This pathogen is increasingly resistant to conventional fungicides, which has increased the need for alternative management methods. The objective of this study was to use in vitro and in planta assays to evaluate 60 Pseudomonas strains for their biocontrol activity against B. cinerea. A dual culture assay was utilized in which one Pseudomonas strain was plated on PDA medium with B. cinerea. The growth reduction of B. cinerea compared to a negative control plate, containing no bacteria, and the zone of inhibition were measured. The in vitro screen identified 20 strains with growth reduction activity against B. cinerea. All 60 Pseudomonas strains were also evaluated in a greenhouse experiment. The individual strains were sprayed on the leaves and growing media of Petunia × hybrida ‘Carpet Red Bright’ plants biweekly for six weeks prior to inoculation with B. cinerea (1x104 conidia/ml). All open flowers were tagged before B. cinerea inoculation and then rated daily for disease severity. A disease severity index was calculated based on the daily ratings. The in vitro and in planta assays were used to select seven top performing bacteria. The bacterial strains identified in this study can be used in future work to develop additional biocontrol options for the effective management of B. cinerea in floriculture crops.