Observations on some Italian provenances of Melampsora populnea

Melmpsora pinitorqua on Populus tremula from Tuscany and M. larici-tremulae on P. tremula from central Alps were artificially inoculated on the same pycnio-aecial hosts in the genera Pinus and Larix, and were compared on the grounds of their pathogenicity and of some morphological aspects. The results indicate that the two rusts can be effectively considered as two separate species as they are different both in their pathogenicity, not withstanding the partially overlapping host range, and their morphology, at least in a few characters.