The rust fungus Puccinia hysterium galls Goat's-beard (Tragopogon pratensis) and may affect most of the plant which can become covered with pale yellow aecia.  There is no host-plant alternation, and no uredinia are produced; later on, dark brown telia occur..

host

Photograph the rust on the host.  Ensure you have noted the host-plant species in your comments

On Goat's-beards and Salsify - grassland, waste ground, allotments, hedgerows, etc.