Colletotrichum associated partitivirus 1 infection negatively modulates the fungal growth of <i>Colletotrichum zoysiae</i> and its virulence to <i>Zoysia matrella</i>

Abstract Anthracnose, caused by Colletotrichum spp., is a severe and devastating disease in turfgrasses. While mycoviruses have been identified in several Colletotrichum isolates from turfgrasses, their effects on host fungal phenotypes remain unclear. This study investigated the impact of Colletotrichum associated partitivirus 1 (CaPV1) infection on Colletotrichum zoysiae isolate MBCT‐264 from Zoysia matrella . CaPV1‐infected and virus‐free C. zoysiae isogenic strains were established through five successive passages on potato dextrose agar (PDA) with or without a virus polymerase inhibitor. Comparative growth analysis on PDA revealed slower growth of the CaPV1‐infected strain compared to the virus‐free strain. Inoculation tests on Z. matrella leaf blades demonstrated that the CaPV1‐free strain produced larger lesions and more pronounced mycelium penetration than the virus‐infected strain. These findings suggest that CaPV1 infection negatively affects both the growth and virulence of C. zoysiae , highlighting the potential of mycoviruses in modulating turfgrass pathogen behavior.