Extracts from the Brown Macroalga Sargassum vulgare for Postharvest Suppression of Potato Fusarium Dry Rot

Sargassum vulgare aqueous and organic extracts were screened in vitro and in vivo for their antifungal potential toward Fusarium sambucinum the most aggressive causal agent of Fusarium dry rot in Tunisia. All extracts had suppressed pathogen growth depending on alga sampling sites, nature of extracts and tested concentrations. Aqueous extracts removed from Monastir, Mahdia1 and Mahdia2, applied at 100 mg/mL, were effective in reducing pathogen growth by more than 36% compared to control. Petroleum ether, methanol and chloroform extracts from Mahdia2, tested at 100 mg/mL, had suppressed F. sambucinum mycelial growth by up to 34%. Tested as tuber treatment Sargassum ethyl acetate extracts removed from Tunis and Monastir (applied at 5 mg/mL) exhibited important disease suppressive abilities by decreasing dry rot lesion diameter by 53.18 and 54.18%, and rot penetration was lowered by 70.66 and 61.85%, respectively, relative to pathogen-inoculated control. Variable amounts of phenolic compounds were determined according to Folin-Ciocalteau method. These results showed that S. vulgare may be explored for the isolation of antifungal compounds for Fusarium dry rot control useful in agriculture.