Melampsora laricis-populina

Various species of Poplar are the primary hosts, bearing yellow uredinia mainly on the leaf undersides; there are corresponding yellow spots on the upper side.  These are considered to be gall-causers.

The alternate host is Larch, bearing the spermogonia and aecia. 

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Widespread in England and Wales.

Status in Leicestershire and Rutland not known.