To clarify the histopathological characteristics of Camellia oleifera that were infected by Colletotrichum fructicola, this study utilized frozen tissue sections, whole-stain clearing and transmission electron microscopy to observe the time of transformation from biotrophic to necrotrophic when Co. fructicola infects leaves, as well as the colonization and expansion of the pathogenic fungus at different stages on the leaves. The Co. fructicola conidia produced germ tubes 2 h post-inoculation, and appressoria began to form 4 h after inoculation. There were two ways that pathogens can use to inv...