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

Several natural compounds that had been previously identified as effec tive potato sprout inhibitors were examined for antifungal activity ag ainst three thiabendazole (TBZ)-resistant strains and a TBZ-sensitive (wild-type) strain of Fusarium sambucinum. Salicylaldehyde was the mos t inhibitory compound of those tested when applied as a volatile and c ompletely inhibited fungal growth at headspace gas levels of 20 mu g/m L 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 compl etely inhibited the wild-type strain. Treatment of tubers with compoun ds after wounding and inoculation with fungal spores was generally ine ffective in suppressing dry rot, possibly due to lack of direct contac t between the fungi and the compounds,