Uromyces junci is a fungus species and plant pathogen which causes rust on various plants including (Rushes) Juncus species.

It appears as a whitish peridium and a pale yellow mass of spores,[3] it can be found on Pulicaria dysenterica, Juncus articulatus, Juncus bufonius, Juncus effusus, Juncus inflexus and Juncus subnodulosus.

[4][5] It is mainly found in Europe, North America, New Zealand and parts of South America.

[6] In 1994, it was found in Japan.

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