Ten-Year Comparison of Fungicide Sensitivity and Mycotoxin Production of Fusarium Head Blight Isolates from Korea

Fusarium head blight (FHB) is an important disease reducing yield and quality of wheat and barley. To study changes in fungicide efficacy over time, 161 FHB isolates (F. asiaticum and F. graminearum) were obtained from infected wheat and barley in the Jeolla provinces of the Republic of Korea from 2010-2013 and 2020-2023. Over 10 years, FHB fungi developed resistance to demethylation inhibitors (DMIs), methyl benzimidazole carbamates (MBCs), and phthalimides, with few exceptions. Also, no significant resistance against succinate dehydrogenase inhibitors (SDHI) and quinoneoutside inhibitors (QoI) was observed, but sensitivity to phenylpyrrole (PP) increased. Mycotoxin production by four representative isolates of both species indicated that higher doses of DMI, DMI + DMI, MBC, MBC + DMI, and PP controlled trichothecenes, whereas zearalenone was controlled only by SDHI. QoI, QoI + DMI, and phthalimide did not control mycotoxin production in either species. Despite resistance development, DMI, MBC, and PP can still be used to control FHB and mycotoxins in wheat and barley in Korea with close monitoring of resistance.