Melampsora medusae epidemic in Washington, US
A leaf-rust epidemic of poplar hybrids (Populus trichocarpa x deltoides) caused by Melampsora medusae (EPPO A2 pest) has been reported from the lower Columbia river in Washington State, US, in autumn 1991. According to the authors it was the first time that poplar hybrids have been attacked by the pathogen in the Northwest of the USA.
Newcombe, G.; Chastagner, G.A. (1992) A leaf-rust epidemic of hybrid poplar along the lower Columbia river caused by Melampsora medusae.
Presentation at the 1992 APS/MPS Annual Meeting, Portland, OR, USA. Phytopathology 82, 1144