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Fungi that cause rot in postharvest of blackberries (Rubus glaucus):Isolation, identification, and evaluation of the most aggressive genus

Abstract:

Background: The blackberry is a food resource of excellent quality. Postharvest losses of blackberries can reach 21% of total production, and is mainly due to fungal rots. The identification of pathogenic fungi responsible for these losses could help to control its development and proliferation. Objective: To isolate and identify different fungi that cause decay during the postharvest period of blackberry, and to establish the most aggressive fungi genus. Methods: Blackberry from the province of Tungurahua in Ecuador was used for the isolation of pathogenic fungi. The fungal strains were purified in Petri plates with PDA medium. The pathogenic fungi were characterized and identified to genus level. Various types of fungi were selected to artificially inoculate in blackberries with two different concentrations, 103 and 105 conidiasmL-1 by two methods, wounding the center of the fruit and immersing the fruits in spore suspensions. In our study were used 432 fruits. The most aggressive fungal genus was determined by calculating the incidence of disease index (IDI) of each mold. The fruits were stored at 4°C and 90% relative humidity up to 14 days. The results were analyzed by ANOVA with a significance level of 95% and with the procedure of Fisher’s least significant difference (LSD). Results: 8 different fungus strains were obtained: Penicillium spp, Botrytis spp, Colletotrichum spp, Mucor spp, Rhizopus spp, Fusarium spp, Geotrichum spp and Cladosporium spp. The highest IDI was obtained with Botrytis spp mold. Conclusions: The two inoculation methods applied in the fruits were effective and caused different rot degrees in the berries (with no statistically significant difference). Botrytis spp was the fungal genus that caused the most severe decay during post harvest period.