Paraben sodium salts for the control of postharvest green and blue molds of citrus fruit

The curative activity of postharvest treatments with sodium methyl (SMP), ethyl (SEP), and propylparaben (SPP) against citrus green and blue molds was evaluated on oranges and mandarins artificially inoculated with Penicillium digitatum and P. italicum, treated about 24 h later, and incubated at 20°C for seven days. Concentrations of SMP, SEP and SPP of 200, 80 and 100 mM, respectively, were selected in previous work and tested in small-scale trials at 20, 50 or 62°C for 30, 60 or 150 s to determine the best dip treatment conditions. Dips at 20°C for 60 s were selected and applied alone or in combination with 25 μl L^-1 of the conventional fungicide imazalil. Imazalil alone, at the very low concentrations of 25 and 50 μl L^-1, was also tested in these trials. All three paraben sodium salts were compatible with imazalil and, in general, the effectiveness of the combination was significantly higher than that of standalone treatments. Effectiveness of sodium parabens, applied alone at 20°C for 60 s, was significantly higher on oranges ('Valencia Late' and 'Lanelate') than on mandarins ('Nadorcott', 'Ortanique' and 'Clemenules'). It can be concluded from this research that aqueous solutions of SMP, SEP and SPP at room temperature show potential as nonpolluting alternatives in integrated postharvest management of citrus decay due to penicillium infection.