Postharvest control of brown rot and Rhizopus rot in plums and nectarines using carnauba wax

The effects of Copernicia cerifera wax (carnauba wax) on the development of Monilinia fructicola and Rhizopus stolonifer in vitro and on infection in nectarines and plums were investigated. Inhibition of mycelial growth and spore germination were assessed on potato dextrose agar amended with carnauba wax at concentrations of 1%. 2%, 3% and 4.5%. The spore germination of both fungi on nectarines covered with carnauba wax was evaluated by scanning electron microscopy. The post-infection and protective effects of carnauba wax (4.5% and 9%) toward brown rot and Rhizopus rot in plums and nectarines were investigated. In the protective tests, fruit were wounded, covered with carnauba wax and then inoculated. For the post-infection tests, fruit were wounded, inoculated and then covered with carnauba wax. There was no mycelial growth of M. fructicola at any of the wax concentrations. R. stolonifer was completely inhibited by carnauba wax at all concentrations except at 1%. There was no germination of spores in vitro for both M. fructicola and R. stolonifer at any concentrations of carnauba wax. There was 50% inhibition of spore germination for M. fructicola and 90% for R. stolonifer on the surface of nectarines covered with 9% carnauba wax. Protective application of 4.5% and 9% carnauba wax significantly reduced incidences of both diseases in nectarines and plums. Post-infection control of both diseases by the application of wax was inefficient. (C) 2010 Elsevier B.V. All rights reserved.