ANTIFUNGAL ACTIVITY OF NATURAL COMPOUNDS AGAINST THIABENDAZOLE-RESISTANT FUSARIUM-SAMBUCINUM STRAINS

Several natural compounds that had been previously identified as effective potato sprout inhibitors were examined for antifungal activity against three thiabendazole (TBZ)-resistant strains and a TBZ-sensitive (wild-type) strain of Fusarium sambucinum. Salicylaldehyde was the most inhibitory compound of those tested when applied as a volatile and completely inhibited fungal growth at headspace gas levels of 20 mu g/mL or lower. Cinnamaldehyde, salicylaldehyde, and thymol prevented all growth when incorporated in media at 0.1% (v/v) levels. TBZ-resistant strains were only partially inhibited by TBZ concentrations that completely inhibited the wild-type strain. Treatment of tubers with compounds after wounding and inoculation with fungal spores was generally ineffective in suppressing dry rot, possibly due to lack of direct contact between the fungi and the compounds,