Antifungal Activities of Anilinopyrimidine Fungicides Cyprodinil and Pyrimethanil against <i>Bipolaris maydis</i>

Anilinopyrimidine (AP) fungicides cyprodinil and pyrimethanil have been introduced for controlling various diseases caused by ascomycetes for almost 30 years, but little is known about their activity against<i>Bipolaris maydis</i>, the causative agent of southern corn leaf blight (SCLB). In this study, the baseline sensitivity of<i>B. maydis</i> to cyprodinil and pyrimethanil was established, and the mean EC₅₀ values were 0.330 μg/mL and 0.599 μg/mL, respectively. Cyprodinil or pyrimethanil treatment could cause an abnormal mycelial morphology. Further analysis revealed that cyprodinil or pyrimethanil treatment impaired the integrity of the cell membrane/wall, inhibited the activities of cellulase and pectinase, and led to mitochondrial fragmentation in<i>B. maydis</i>. Additionally, the expression levels of related genes, <i>CGS</i>, <i>CBL</i>, <i>Bccel5A</i>, and <i>Bcpme2</i>, were significantly reduced. Greenhouse and field trials showed that both cyprodinil and pyrimethanil exhibited good control efficacy against SCLB. In conclusion, this study indicated that cyprodinil and pyrimethanil could be potential fungicides for SCLB management.