Rust Fungus

Rusts are fungal plant pathogens of the order Pucciniales, previously known as Uredinales, that cause plant diseases. An estimated 168 rust genera and roughly 7,000 species are currently accepted, more than half of them in the genus Puccinia. Each rust species is specialized to a range of host plants and cannot infect non-host species, and most cannot survive in laboratory culture, requiring a living plant host to complete their life cycle; their common name comes from the powdery rust-colored or brown spore deposits they leave on plant surfaces.