Puccinia
Puccinia is a genus of fungi. All species in this genus are obligate plant pathogens and are known as rusts. The genus contains about 4000 species. Taxonomy. Examples of "Puccinia" rusts and the diseases they cause: The rust species "Puccinia obtegens" has shown some promise for controlling Canada thistle, but it must be used in conjunction with other control measures to be effective. Another leaf rust species, "Puccinia myrsiphylli", has been used as an effective biocontrol agent for infestations of the common form of bridal creeper ("Asparagus asparagoides") in Australia since 2000.