Violet Bramble Rust (Phragmidium violaceum) is a gall-causing rust on Bramble (Rubus fruticosus agg.).  There is no host-plant alternation.  Aecia, uredinia and black telia are on the leaf undersides, with a corresponding large, rounded and intensely violet spot on the upperside.  Aecia can also be borne on the stems, in reddish spots with a violet margin.  The teliospores are warty and have long pedicels; they are divided into 3 - 5 cells and have a short apiculus.

Phragmidium bulbosum telia are very similar, but do not have a corresponding violet spot on the leaf upperside.   The yellow uredinia of Kuehneola uredinis can be borne on stems.  Note that insects, physical damage or other source can also cause discolouration and reddish or purplish marks and spots on bramble leaves.   

host/telia/violet spot

Photograph the rust on the host, on both upper and lower sides of leaf, showing the violet spot and the telia or uredinia under the leaf.  Ensure you have noted the host-plant species in your comments.  We recommend that teliospores are examined.

Brambles