Summary statement BdUth1, a member of the SUN protein family, interacts with BdAtg8 and functions as a key regulator of vegetative growth, conidial morphogenesis and pathogenicity in Botryosphaeria dothidea . BdUth1‐mediated mitophagy is critical for the pathogenicity in B. dothidea , providing valuable insights for the future development of gene‐targeting fungicides.