Conifer - Cottonwood rust

Conifer - Cottonwood rust - <em>M. occidentalis</em> uredinia on cottonwood leaves
  • Latin name: Melampsora occidentalis Jacks.
  • French name: Rouille des conifères et du peuplier de l'Ouest
  • Division: Basidiomycota
  • Class: Uredinales


Leaf, Needle



Damage, symptoms and biology

Melampsora occidentalis, like the other Melampsora rusts, causes more serious damage to hardwoods than to its conifer hosts.

Other information

The aecia and telia of Melampsora occidentalis are macroscopically similar to those of M. albertensis and M. medusa. However, the aeciospores and urediniospores of M. occidentalis are significantly larger.

Canadian Forest Service Publications

Conifer - Cottonwood rust

Information on host(s)

Main host(s)

Balsam poplar, black cottonwood, European larch, Jananese larch, narrowleaf cottonwood, ponderosa pine, Rocky Mountain Douglas-fir, shore pine, Sitka spruce, western larch, western white pine

  • Conifer - Cottonwood rust Yellow discoloration of leaves associated with uredinia on cottonwood
    Brenda Callan
  • Conifer - Cottonwood rust M. occidentalis uredinia on cottonwood leaves
  • Conifer - Cottonwood rust Aecia and spermogonia of Melampsora occidentalis on Monterey pine seedling
    Wolf Ziller
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