Comparison of virulence of Fusarium oxysporum f. sp. radicis-cucumerinum isolates from different regions of Iran and their impact on vegetative growth of cucumber

Fusarium wilt on cucumber caused by Fusarium oxysporum f. sp. radicis-cucumerinum is an important and common disease of cucumber in Iran. In this study, differences of pathogenicity between several isolates and their impact were assessed on the plant growth parameters. The pathogenicity of 50 isolates collected from cucumber plants with wilting and yellowing symptoms from different geographic areas of Iran, were examined on cucumber, Negin cultivar. The inoculated and control plants were placed at 25°C for 14 days. Disease severity and the weight of root and crown were measured 10 days post-inoculation. Studied factors showed significant difference at 1% level among isolates of F. oxysporum f. sp. radicis-cucumerinum. The maximum percentage of disease was observed in plants treated by F-111-2, F-133-2 and H8; while the highest disease severity induced in plants treated by F-111-2, F-160-12 and F-111-5. F-111-5, F-160-12 and F-121-4 incited the most decrease in root weight. The crown weight decrease in the presence of F-160-12, F-121-4 and F-111-10 isolates of Fusarium oxysporum f. sp. radicis-cucumerinum correspondingly. Totally, due to the results, it could be concluded that f-160-12 can be considered as the most severe pathogenic isolate.