Difference between chitosan and oligochitosan in growth of Monilinia fructicola and control of brown rot in peach fruit

Chitosan (CS) and oligochitosan (OCS), as natural antifungal agents, have been primarily used as alternatives to synthetic chemical fungicides to control postharvest diseases of fruits. The effectiveness of these two agents on the growth of Monilinia fructicola to control brown rot has not yet been reported. Both spore germination and mycelial growth of M. fructicola were strongly inhibited by CS and OCS treatments in this study. Moreover, the inhibitory effect of both agents was more obvious on mycelial growth than on spore germination. By comparison of the half maximal inhibitory concentration (IC50) of each, OCS treatment conferred a little better inhibitory effect on fungal growth in vitro, but the effectiveness of both treatments on brown rot control in peach fruit stored at 25 °C was very similar. The integrity of the plasma membrane of CS- or OCS-treated spores was obviously lower than that of the control. Cytoplasm leakage was significantly higher in chitosan-treated mycelia than that of the control. These results suggest that both chitosan and oligochitosan used in this study are promising natural fungicides for control of brown rot of peach.

► Chitosan and oligochitosan are effective on inhibition growth of Monilinia fructicola. ► The effectiveness of oligochitosan was higher than that of chitosan in vitro. ► Chitosan and oligochitosan disrupted the integrity of the plasma membrane of spores. ► The efficacy of both agents on brown rot control in peach fruit was very similar. ► Two agents are promising natural fungicides for control of brown rot of peach.