Combining Pantoea agglomerans (CPA-2) and curing treatments to control established infections of Penicillium digitatum on lemons

Abstract

The effectiveness of the strain CPA-2 of Pantoea agglomerans alone or in combination with a curing treatment at 33°C for 65 h to control green mold was evaluated on lemons stored at ambient temperature and in cold storage. An application of P. agglomerans at 2 × 108 CFU/ml effectively reduced green mold incidence on recently inoculated lemons stored at temperatures from 5 to 25°C. Moreover, a 30-s immersion of lemons in a P. agglomerans suspension at 2 × 108 CFU/ml significantly reduced green mold incidence, even when delayed up to 15 h after inoculation with Penicillium digitatum at either 20°C or while in cold storage. However, it failed to control established infections of P. digitatum of more than 24 h. Curing P. agglomerans-treated lemons at 33°C for 65 h completely controlled 24-h-old infections on artificially inoculated lemons stored at 20°C for 14 days and on naturally infected lemons stored at 10°C for 3 weeks plus 7 additional days at 20°C. When applied before curing, population growth of P. agglomerans in wounds was similar to that within wounds of control fruits at 20°C. In contrast, when it was applied immediately after curing treatment, P. agglomerans populations within wounds did not increase.