Reduced pathogenicity in ΔVdpf. (A) Necrosis and defoliation in intact cotton plants (Gossypium hirsutum L.) at 20 days post‐inoculation with 4 × 107 conidia of WT, ΔVdpf mutants, IMΔVdpf mutants and complemented strains. (B) Virulence measurements on tobacco plants (Nicotiana benthamiana). (C) Infection of WT, ΔVdpf mutants, IMΔVdpf mutants, complemented strains and CK in root cortical cells and the vascular bundle. (D) Detection of fungal biomass in infected plant roots. WT, wild‐type Verticillium dahlia; ΔVdpf, deletion mutant; IMΔVdpf, insertion mutant; Com, ΔVdpf:Vdpf‐phleo mutant; CK, plant roots inoculated with sterile water. Scale bars, 50 μm. Vdpf, VDAG_08521.1.