Isolation and in vivo screening of yeast antagonists for the control of Botrytis cinerea and Penicillium expansum of pome fruit

A total of 100 epiphytic yeast isolates were obtained from the fruit surface of ‘Golden Delicious’ apples and ‘Packham’s Triumph’ pears, and screened against Botrytis cinerea and Penicillium expansum, the causal agents of grey and blue moulds, respectively. Fifteen yeast isolates reduced grey mould incidence by more than 50%, when applied 4 h before inoculation with B. cinerea. Similarly, seven yeast isolates reduced blue mould incidence by more than 50%, when applied 4 h before inoculation with P. expansum. Yeast Isolates YP16, YP24, YP25, and YieldPlus^®, a commercial biological control agent, provided the best control of grey mould on apples when applied 48 h prior to inoculation with B. cinerea. This reduction was significantly different (P<0.001) compared to the untreated control. Furthermore, YieldPlus^® and yeast Isolates; YP28, YP53, YP60, YP43, YP5, YA33 and YP84, when applied 48 h prior to inoculation with P. expansum, significantly (P<0.05) reduced blue mould incidence compared to the untreated control. YieldPlus^® and the yeast Isolate YP25 provided the best control of B. cinerea, while isolate YP60 and YieldPlus^® provided the best control of P. expansum on ‘Golden Delicious’ apples. A mixture of YP25 and YP60 provided complete control of both B. cinerea and P. expansum when applied to ‘Golden Delicious’ apples before inoculation. The benefits of using yeast antagonists as a measure to reduce the use of agrochemicals on postharvest fruit diseases is discussed.