Chitosan and fungicides on postharvest control of Guignardia citricarpa and on quality of ‘Pêra Rio’ oranges

Abstract

Citrus fruits are affected by the black spot disease caused by the fungus Guignardia citricarpa. Chitosan can be used as covering for fruits and may delay the ripening process and inhibit the growth of some fungi. Thus, the control of citrus black spot using chitosan a nd the fungi cides thia bendazol e a nd ima za li l wa s assessed in addi tion to the physicochemi cal qu al ity of ‘Pêr a Rio’ oranges. The or a nges wer e immer sed into chi tosa n, thi a benda zol e or imazalil, and in chitosan mixed with both fungicides. The fruits were then stor ed at 25 °C, 80% RH, for 7 days a nd, after this storage period, subjected to physicochemical analyses. Chitosan in association with the fungicides reduced black spot in ‘Pêra Rio’ ora nges a nd delayed the change in the ora nge sk in colour from green to yellow during the postharvest storage. Total soluble solids, ti tra tabl e a cidity, pH, a scorbic acid cont ent and ra tio wer e not influ enced by the t rea tments. Thu s, chi tosa n a ppl i ed with the fungicides thiabendazole and imazalil showed potential to control the development of black spot lesions on ‘Pêra Rio’ oranges during the postha rvest per iod.