Fungal Pathogen Diversity and Fungicide Resistance Assessment in Fusarium Crown Rot of Wheat in the Huanghuai Region of China

Fusarium crown rot (FCR) poses a major threat to wheat production in the Huanghuai wheat region of China. This study aims to enhance understanding of pathogen populations causing FCR, focusing on their pathogenicity, trichothecene genotypes, and fungicide resistance. During the 2022-2023 growing seasons, we collected 1820 fungal isolates from 233 locations in this region. Our results identified <i>Fusarium pseudograminearum</i>, <i>Fusarium graminearum</i>, and <i>Fusarium asiaticum</i> as the primary pathogens, with <i>F. pseudograminearum</i> exhibiting the highest virulence. Three trichothecene genotypes were identified, including nivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol. No correlation was observed between trichothecene genotype and virulence, except in <i>F. asiaticum</i>. Antifungal assays demonstrated that all six tested fungicides effectively inhibited <i>F. pseudograminearum</i>, with fludioxonil being particularly effective. Field surveys identified isolates resistant to difenoconazole and pyraclostrobin. Laboratory analysis also revealed strains with FpSdhC₁^{A83 V} and FpSdhC₁^S80N mutations conferring resistance to cyclobutrifluram. These findings offer critical insights for developing effective control strategies to manage FCR.