The infection hyphae become elongated and septated resulting in larger primary hyphal. At this stage of infection, the pathogen invaded the host cells without killing them. Subsequently at 72 HAI, the pathogen shifted to its necrotrophic phase where a narrow secondary hyphae started to branch out from primary hyphal within the host epidermal cell. This was followed by the massive growth of both intra- and intercellular hyphae. As the primary and secondary hyphae radiated from cell to cell, infected cells gradually lost their viability and a small whitish water-soaked lesion appeared on the surface of the leaves.