Enhancement of the efficacy of two antagonistic yeasts with salicylic acid against Penicillium expansum

In this study, the yeasts Pichia guilliermondii and Candida membranifaciens in combination with salicylic acid (SA) were tested for biological control against Penicillium expansum at 20°C. In vitro studies showed that SA at 200 μg/mL had reduced the mycelial growth of pathogen significantly. SA at 10, 50 and 100 μg/mL increased the population of P. guilliermondii while it reduced the population of C. membranifaciens. In vivo studies showed that although both P. guilliermondii and C. membranifaciens had potential to control blue mould, combination of P.guilliermondii with SA at 50 μg/mL and C. membranifaciens with SA at 5 μg/mL improved their efficacy. Our results showed that SA at 5 μg/mL had no effect on P. guilliermondii and C. membranifaciens after 7 days, while at 50 μg/mL reduced the population of P. guilliermondii, and SA at concentration higher than 10 μg/mL reduced the population of C. membranifaciens after 15 days at 20°C.