Effect of different coating-forming agents on the efficacy of the biocontrol agent Candida sake CPA-1 for control of Botrytis cinerea on grapes

• Polymer type influenced Candida sake survival and efficacy against Botrytis cinerea.
• High ratios solids:CFU promoted better biocontrol activity of C. sake.
• Surfactants allowed a better cell dispersion on grapes but not additional positive effect.
• Caseinate or starch are the most suitable coatings to obtain formulated biocontrol C. sake products.

Multiple formulations of known biocontrol agent (BCA) Candida sake, containing different coating-forming polymers and surfactants were tested at different polymer:BCA ratios, in order to improve control of Botrytis cinerea on grapes. The BCA cell viability on the grape surface was analyzed and reduction in disease incidence and severity was determined. Coating-forming solids improved the survival and efficacy of C. sake as a BCA against B. cinerea, depending on the polymer type and ratio. The incorporation of surfactants did not improve survival or disease control, although they promoted a better cell dispersion on the grape surface. Cell growth of the antagonist during incubation led to the formation of aggregates, even when surfactants were present. Sodium caseinate and starch were the most suitable polymers to formulate C. sake preparations to obtain coating-forming systems with this BCA and to increase its survival and efficacy at the minimum economic cost of the ingredients.

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