Fir-fireweed rust

• French disease name: Rouille du sapin et de l'épilobe
• Pathogen name: Pucciniastrum epilobii G. Otth
• Kingdom: Fungi
• Phylum: Basidiomycota
• Class: Pucciniomycetes
• Order: Pucciniales
• Family: Pucciniastraceae
• Partial list of synonyms:
  • Pucciniastrum abieti-chamaenerii Kleb.
  • Uredo fuschsiae Arth. & Holw., hom. Illeg.

Distribution

Canada

Damage, symptoms and biology

The fungus causes fir needles to wilt and drop prematurely. In severe infections of young trees, the disease can cause a severe reduction in growth. The fungus lives on two hosts in alternation, balsam fir and fireweed Epilobium sp., a plant with purple, lilac coloured flowers. While living on its fireweed host, the fungus occasionally infects other ornamental plants in the same family. In spring, small white blisters develop on the lower surface of balsam fir needles. The yellow-orange spores discharged from these blisters end up infecting the young shoots of fireweed plants.

Other information

Fireweed is a beautiful wild plant but it should not be naturalized in our gardens because it is highly invasive and serves as the primary vector for the disease. In Christmas tree plantations, it is important to remove the alternate host to prevent the disease from appearing in the crop trees.

Canadian Forest Service Publications

Fir-fireweed rust

Information on host(s)

Main host(s)

Amabilis fir, balsam fir, grand fir, subalpine fir, white fir, willow-herb

Photos

Rust on needles

Richard Porrelier

Rust on needles

Rust on needles

Uredinia of P. epilobii on the lower surface of a fireweed leaf

Wolf Ziller

Fireweed, the alternate host of Pucciniastrum epilobii, the causal agent of a needle rust of balsam fir.

Fruiting of Pucciniastrum epilobii, the cause of a needle rust of balsam fir, on infected needles.