In vitro and in vivo inhibitory effects of gaseous chlorine dioxide against Fusarium oxysporum f. Sp. batatas isolated from stored sweetpotato: Study II

Chlorine dioxide (ClO₂) has been widely used as an effective disinfectant to control fungal contamination during postharvest crop storage. In this study, Fusarium oxysporum f. sp. batatas SP-f6 from the black rot symptom of sweetpotato was isolated and identified using phylogenetic analysis of elongation factor 1-α gene; we further examined the in vitro and in vivo inhibitory activities of ClO₂ gas against the fungus. In the in vitro medium tests, fungal population was significantly inhibited upon increasing the concentration and exposure time. In in vivo tests, spore suspensions were drop-inoculated onto sweetpotato slices, followed by treatment using various ClO₂ concentrations and treatment times to assess fungus-induced disease development in the slices. Lesion diameters decreased at the tested ClO₂ concentrations over time. When sweetpotato roots were dip-inoculated in spore suspensions prior to treatment with 20 and 40 ppm of ClO₂ for 0-60 min, fungal populations significantly decreased at the tested concentrations for 30-60 min. Taken together, these re-sults showed that ClO₂ gas can effectively inhibit fungal growth and disease development caused by F. oxysporum f. sp. batatas on sweetpotato. Therefore, ClO₂ gas may be used as a sanitizer to control this fungus during postharvest storage of sweetpotato.