Comparison of the Antifungal Activity of Chlorine Dioxide, Peracetic Acid and Some Chemical Fungicides in Post-harvest Management of Penicillium digitatum and Botrytis cinerea Infecting Sweet Orange and Strawberry Fruits

Penicillium digitatum and Botrytis cinerea are some of the most important post-harvest pathogenic fungi infecting vegetables and fruits. This study is aimed to assess the antifungal potency of chlorine dioxide (ClO₂) and peracetic acid (PAA) by examining the growth of P. digitatum and B. cinerea on inoculated potato-dextrose-agar medium (PDA), sweet orange and strawberry fruits under in vitro and storehouse conditions. Furthermore, the antifungal efficacy of ClO₂ and PPA was compared with four commercial fungicides namely Thiabendazole, Imazalil, Cyprodinil and Thiophanate-methyl (1000 mg/L). The results indicated that the antifungal activity of ClO₂ and PAA under both in vivo and in vitro conditions were similar to the chemical fungicides. At lower concentration, ClO₂ was more active than PAA. The radial growth of pathogenic fungi in PDA medium was completely inhibited by 100 ppm ClO₂ and 750–900 ppm PAA. Under the storehouse condition, application of 400 ppm ClO₂ and 1050 ppm PAA completely inhibited the test fungi on orange and strawberry fruits. No significant difference was observed in the total sugar content of the fruits following application of the test compounds at these concentrations. This study concludes that ClO₂ and PAA can be used as viable substitutes for chemical fungicides for the management of P. digitatum and B. cinerea in sweet orange and strawberry fruits.