Dilophia, Rhytisma, &c. Moreover, variegations deceptively like these disease spots are known, e.g.

Each plant has different variegations, so there's always something different.

Hosta (genus) Deciduous clumps of succulent leaves in shades of gray green and gold with various variegations.

They gleam in green, lime, gold, and subtle variegations of cream, green, silver and gray.

Albinism, with which variegated foliage may be considered, concerns a different set of causes, still obscure, and usually regarded as internal, though experiments go to show that some variegations are infectious.