Fusarium head blight in Argentina: Pathogen aggressiveness, triazole tolerance and biocontrol-cultivar combined strategy to reduce disease and deoxynivalenol in wheat

Abstract

Fusarium head blight (FHB) management includes genetic and biological techniques, together with good agronomic practices. The combined use of chemical and biocontrol strategies along with moderately resistant wheat cultivars is a promising approach to manage the disease. The application of fungicide has shown a reduction in disease severity and mycotoxins accumulation in grains, during natural or artificial infections. Previously, we have demonstrated that Bacillus velezensis RC218 was able to diminish FHB severity and deoxynivalenol (DON) accumulation on harvested grains in bread and durum wheat under field conditions in two locations. The aims of the present study were to evaluate both triazole-based fungicides tolerance of Fusarium graminearum ss populations isolated from wheat in Argentina and the aggressiveness of F. graminearum ss strains with different trichothecene profiles on wheat cultivars, and to determine the efficiency of a biocontrol agent on disease severity, DON accumulation on moderately resistant wheat cultivars tested under greenhouse conditions. The strains evaluated against tebuconazole, prothioconazole and the mixture of both showed an intermediate susceptibility growing under in vitro assays, and few of them showed high tolerance to the evaluated fungicides. Regarding strains aggressivity, 8 Fusarium graminearum ss and 1 Fusarium meridionale strains were able to produce disease severity from 10 to 35% and deoxynivalenol from 0.2 to 10 ppm during field trials. The interaction of a biocontrol agent and moderately resistant wheat cultivars, tested under greenhouse trials, showed a better performance of moderately resistant wheat cultivar MS INTA 415 when Bacillus velezensis RC218 was applied. Significant reduction on disease severity (43%) and deoxynivalenol accumulation (60%) were also observed when the biocontrol agent was applied to moderately susceptible wheat cultivar K. Liebre. Taking into account the climate change, further research will be needed to study combined strategies with fungicides, biocontrol and less susceptible wheat cultivars to manage FHB severity and mycotoxin accumulation.