Combination of uv-c radiation and chitosan films enriched with essential oils for fungi control in papaya ‘Maradol’

Abstract Anthracnose and soft rot cause deterioration of quality as well as large losses during post-harvest handling of papaya fruits. The single strategies for disease control is little efficient. We analyzed the effect of to integrate control strategies on the incidence of disease caused by the inoculation of spores of the fungi Colletotrichum gloeosporioides (Penz.) and Rhizopus stolonifer (Ehrenb.) into papaya (Carica papaya L.) ‘Maradol’. The following treatments were evaluated: a combination of the use of composite films made with chitosan (15 g L-1) enriched with clove, thyme and / or lime essential oils, (EO) (5 or 10 mL L-1 of each EO) and three irradiation UV-C doses (0.97 kJ·m-2, 2 kJ·m-2 y 2.88 kJ·m-2), applied at 12, 24, and 48 h post-inoculation of phytopathogens spores. The treatment where combined coating with 10 mL L-1 of clove EO and 10 mL L-1 of thyme EO and a UV-C irradiation at dose of 2.88 kJ m-2 (B1T92) applied at 24 h post-inoculation was able to maintain the disease incidence lower than 25% (for both fungi) during nine days of storage at tropical room conditions (28 ± 3 °C and 80% RH). The same treatment reduced the specific rate of the disease, with values of 0.549 and 0.029 d-1 for C. gloeosporoides and R. stolonifer, respectively. Other treatments (B2T62, B1T34, B1T34, and B1T94) had antifungal activity (mean values of incidence of 35% throughout storage) for R. stolonifer. These results demonstrate that the synergistic effect of the use of biofilms enriched with EO and UV-C irradiation controls the development of fungi causing anthracnose and soft rot in Maradol papaya fruits.