Botrytis cinerea, an airborne necrotrophic fungus is one of the most important and destructive pathogens of greenhouse-grown ornamental crops. The pathogen incites leaf, stem, and flower blight reducing plant quality and marketability. The overall goal was to provide growers with disease management options by combining host resistance and biorational products. Geranium and petunia cultivars were screened for resistance and biorational products were evaluated for efficacy against B. cinerea. 'Ringo 2000 Violet' and 'Maverick Scarlet Picotee' geranium was significantly more susceptible than 'Pinto Premium Orange' and 'Horizon Coral Spice'. Most of the biorational products applied to 'Pinto Premium Orange' effectively controlled B. cinerea. In contrast, only few products provided effective control in 'Ringo 2000 Violet'. In 'Pinto Premium Orange', disease assessment indicated that Bacillus amyloliquefaciens, Pseudomonas chlororaphis, Aureobasidium pullulans, and extract of Swinglea glutinosa provided a level of efficacy similar to the fungicide standard fenhexamid. In 'Ringo 2000 Violet', S. glutinosa resulted in protection similar to the fenhexamid across both trials. 'Tidal Wave Cherry' petunia had significantly higher disease severity and AUDPC values than 'Sophistica Blackberry' for each trial. According to AUDPC value, 'Shock Wave Red' had significantly less disease than 'Tidal Wave Cherry' and was similar to 'Sophistica Blacberry'. Efficacy of biorational products on 'Shock Wave Red' petunia showed that A. pullulans and Gliocladium catenulatum effectively limited disease similar to fenhexamid. Host resistance could reduce fungicide inputs and be used in combination with biorational controls for effective Botrytis blight control.
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