Introduction. Rhizopus stolonifer is the
causal agent of Rhizopus rot disease in various fruit and vegetables.
Materials and methods. The effect of chitosan was evaluated in
vitro on mycelial growth, sporulation, morphological characteristics and
germination of spores of three isolates of R. stolonifer (from peach,
papaya and tomato). The effect of chitosan on controlling Rhizopus decay
in peach, papaya and tomato fruit in situ in comparison with the
synthetic fungicide dichloran was also studied. Results and discussion. Our
results showed that the mycelial growth and sporulation of the three isolates were
markedly inhibited at all tested chitosan concentrations. The highest antifungal indexes
and sporulation reduction were observed with chitosan at 2 mg·mL–1. In our
study, the morphological characteristics of the spores of R. stolonifer
showed different behavior depending on the evaluated isolates. In general, the highest
effect on germination was observed at the chitosan concentration of 2 mg·mL–1.
Our results demonstrated that chitosan was effective in reducing the percentage of
infection and the severity index on peach, papaya and tomato fruit compared with those of
non-treated control. The chitosan was not more effective than dichloran in reducing the
percentage of infection. The results of the study suggest that chitosan
(2 mg·mL–1) is a good alternative for the control of
Rhizopus decay on peach, papaya and tomato fruit; it could be
considered as a potential agent in natural alternatives to control postharvest
diseases.