Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2004
Publication Date: 1/1/2004
Citation: Plaza, P., Usall, J., Smilanick, J.L., Lamarca, N., Vinas, I. 2004. Combining pantoea agglomerans (cpa-2) and curing treatments to control established infections on penicillium digitatum on lemons. Journal of Food Protection 67:781-786. Interpretive Summary: Synthetic fungicides are used on citrus and many other fresh fruits to protect them from decay by postharvest fungal pathogens, and their residues raise health concerns worldwide. In this study, we combined two approaches that eliminate the need to add fungicides to the fruit to control the most common postharvest diseases of citrus. The approaches were biological control, using a bacterium that inhibits fungal growth, and thermal curing, where the fruit are placed at high temperatures for up to several days to inhibit these pathogens. The combination was very effective, and showed this approach has sufficient promise to warrant commercial evaluation.
Technical Abstract: The effectiveness of the strain CPA-2 of Pantoea agglomerans alone or in combination with a curing treatment at 33ºC for 65h to control green mold was evaluated on lemons stored at ambient and cold storage. An application of P. agglomerans at 2x108 CFU/ml effectively reduced green mold incidence on recently inoculated lemons stored at different temperatures from 5ºC to 25ºC. Moreover, a 30-s-immersion of lemons in a P. agglomerans suspension at 2x108 CFU/ml significantly reduced green mold incidence even when delayed up to 15h after inoculation with P. digitatum at either 20ºC or cold storage. However, it failed to control established infections of P. digitatum of more than 24h. Curing P. agglomerans treated lemons at 33ºC for 65h completely controlled 24-h-old infections on artificially inoculated lemons stored at 20ºC for 14 days and on naturally infected lemons stored at 10ºC for 3 weeks plus 7 additional days at 20ºC. Curing treatment did not negatively affect population growth of P. agglomerans in wounds and was similar to that within wounds of control fruits at 20ºC. In contrast, P. agglomerans was not able to increase its population size when was applied immediately after curing treatment.