Biocontrol of fruit postharvest diseases by Aureobasidium pullulans

Abstract: The activity of a biological control agent, strain LL, previously identified asAureobasidium pullulans, was tested for the first time on peach, apple and orange artificiallyinoculated with Monilinia laxa, M. fructicola, M. fructigena (peach) and Botrytis cinerea,Colletotrichum acutatum, Penicillium expansum (apple) and P. digitatum, P. italicum (orange).The washed cells of the antagonist were effective against all eight pathogens, inhibiting decay byover 94%; in particular the antagonist completely controlled M. laxa, M. fructicola, C. acutatum,P. digitatum and P. italicum. To our knowledge this is the first study considering the biocontrolof eight postharvest fruit pathogens with an A. pullulans strain in the same experimentalconditions. Under postharvest conditions, in peaches inoculated with Monilinia spp., treated withthe antagonist and stored at 0°C for 21 days plus 7 days of shelf-life, the antagonist was able tocompletely inhibit M. laxa and M. fructicola. In the same way, blue mould caused byP. expansum was significantly reduced on apple, after 120 days at 0°C, plus 7 days at 20°C. In invitro trials, the VOCs released by the antagonist significantly inhibited the growth of all seventested pathogens compared to the control, although with a different rate depending on thepathogen. These preliminary data, showing the efficacy of the A. pullulans LL strain in thecontrol of the main postharvest fruit diseases, are promising for the development of abiofungicide for postharvest applications on a wide range of species and pathogens.