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Tomentosus root rot

Tomentosus root rot - Fruiting bodies
  • Latin name: Inonotus tomentosus (Fr.:Fr.) Teng
  • French name: Carie rouge alvéolaire du pied
  • Division: Basidiomycota
  • Class: Aphyllophorales
  • Synonym(s): Coltrichia tomentosa (Fr.:Fr.) Murrill,
    Onnia tomentosa (Fr.:Fr.) P. Karst.,
    Polyporus tomentosus Fr.:Fr. var. tomentosus,
    Polyporus tomentosus Fr.:Fr.


Trunk, Root



Damage, symptoms and biology

The fungus causes red butt rot in the woody tissues of the roots and the lower part of the trunk. The spores gain entry through a wound on the roots or on the trunk and the infection spreads toward the main root and the large lateral roots. Once the fungus is well established in the roots, it can infect other trees if their roots touch those of its host. Around the end of summer, many fungal fruiting bodies develop on the roots and the trunk. The fruiting body has a slightly velvety surface and is a yellowish buff colour when young. The underside of the fungus bears many tiny pores and is brownish buff in colour. The decay is characterized by a red discoloration in the affected area of wood. Later, pockets filled with matts of white fibers develop in the wood. While infected trees can resist the disease for a few years, it makes them more vulnerable to other pathogens.

Other information

Since the infected trees are vulnerable to wind throw, they should be removed promptly from areas where they can cause damage, such as in white spruce plantations.

Canadian Forest Service Publications

Tomentosus root rot

Information on host(s)

Main host(s)

Black spruce, Engelmann spruce, Norway spruce, white spruce

Secondary host(s)

Amabilis fir, balsam fir, eastern white pine, grand fir, jack pine, ponderosa pine, red pine, Rocky Mountain Douglas-fir, shore pine, Sitka spruce, subalpine fir, western hemlock, western larch, western redcedar, western white pine, whitebark pine


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