Improving control of storage diseases on apple by combining biological and physical post-harvest methods

Post-harvest non-chemical treatments consists of a large range of different approaches, including strengthening of the commodity’s natural defence mechanisms, thermotherapy, application of antagonistic microorganisms and natural antimicrobial substances. NEX0101 is a promising antagonistic biocontrol agent containing the yeast Candida oleophila as the active ingredient. NEX0101 was developed by Bionext, a spin-off from the laboratory of Dr. H. Jijakli, and is currently evaluated for commercial use. The product contains a yeast strain isolated from apple fruit and was originally developed for the control of post-harvest diseases on apple. The antifungal effectiveness of this antagonist can be increased by addition of calcium salts. As the mode of action of this yeast is based on the colonisation of wounds, the mean targets of NEX0101 are blue mould, caused by Penicillium expansum, and grey mould, caused by Botrytis cinerea. Facing possible latent infections, thermotherapy by using hot water treatments could provide an advanced control towards lenticelrot (Gloeosporium spp.). A combination of both physical and biological treatment techniques could broaden the spectrum to all key pathogens on apple and pear. The use of NEX0101 for the control of P. expansum was examined in combination with calcium gluconate. According to the results the combination NEX0101 with calcium gluconate provides an advanced mould control towards P. expansum The best results were achieved using NEX0101 in combination with post-harvest dipping by thermotherapy. The hot water treatment alone was clearly inefficient towards wound parasite P. expansum, on the contrary thermotherapy stimulates the decay caused by this postharvest pathogen. For the future a combination of biological and physical treatments could offer a worthy non-chemical alternative for organic and integrated fruit growers towards fruit rot decay, although more research is necessary to implement these methods in practice