Viral damage to leaves. Mottling and yellowing of the leaves of a strawberry plant (Fragaria sp. ) caused by a virus. Some of the leaves are displaying chlorosis, a yellowing of the leaf caused by destruction and ceased production of the pigment chlorophyll. Viruses which attack strawberry plants include strawberry mottle virus, crinkle virus and mild yellow edge virus. These agents are transmitted from plant to plant by insects, typically the aphid Pentatrichopus fragefolii. Plant viruses are rarely lethal at the onset of the infection, but commonly reduce the life of the plant by spreading and interfering with its metabolism.