Fusarium Species Recovered from Wheat and Barley Grains in Uruguay, Pathogenicity and Deoxynivalenol Content

Resumo

Grain samples from five wheat and five barley cultivars from different locations and planting dates were examined for the presence of Fusarium species. Fusarium graminearum was the primary species associated with FHB (Fusarium head blight). It comprised 76 % and 60 % of all Fusarium species isolated from wheat grains in 2001 and 2002, respectively. Fusarium graminearum represented 65 % and 56 % of all Fusarium species isolated from barley grains in 2001 and 2002, respectively. The frequencies with which Fusarium species other than F. graminearum were recovered varied depending on both environment and host cultivar. In general, F. avenaceum, F. culmorum and F. poae were the following most common species isolated from wheat grains, whereas F. equiseti, F. acuminatum, and F. trincictum were less frequently isolated. Fusarium poae and F. equiseti were the most common species isolated from barley grains after F. graminearum. Other Fusarium species recovered in barley grains included F. avenaceum, F. sambucinum, F. trincictum, F. semitectum, and F. chlamydosporum. All species were pathogenic on wheat and barley in inoculation tests in the greenhouse, except F. semitectum on wheat. Greater FHB severity and incidence on wheat and barley spikes were obtained with the F. graminearum isolates, followed by F. avenaceum and F. poae. Cultivars previously characterized as moderately resistant to moderately susceptible showed the lowest FHB incidences, severities, percentages of Fusariuminfested grains, and grains infested with F. graminearum in this field study. Data from this study raise the concern of the possible presence of mycotoxins other than DON (deoxynivalenol) in wheat and barley grains.