White mottled rot

• French disease name: Carie blanche madrée
• Pathogen name: Ganoderma applanatum (Pers.) Pat.
• Kingdom: Fungi
• Phylum: Basidiomycota
• Class: Agaricomycetes
• Order: Polyporales
• Family: Polyporaceae
• Partial list of synonyms:
  • Elfvingia megaloma (Lév.) Murrill
  • Fomes applanatus (Pers.) Gilb.
  • Fomes leucophaeus Mont.
  • Fomes megaloma (Lév.) Cooke
  • Ganoderma megaloma (Lév.) Bres.
  • Polyporus applanatus (Pers.) Walls.

Distribution

Canada

Damage, symptoms and biology

The fruiting bodies of Ganoderma applanatum are brown with a white margin on the upper surface. The underside is white, but turns black when rubbed. The fruiting bodies are tablet-shaped, and are hard and persistent. Ganoderma applanatum is an important decay of dead trees but may enter living trees through wounds and cause extensive damage. In hemlock, decay is considered to extend 3 m above and below a sporophore.

Other information

A related species, Ganoderma oregonense (Pers.) Pat., also causes a root and butt rot of living and dead trees in western North America, particularly on true firs and western hemlock. Sporophores of this fungus are often very large (up to 80 cm across), and have a shiny reddish upper surface. Unlike G. applanatum, the pore surface does not darken when bruised.

Canadian Forest Service Publications

White mottled rot

Information on host(s)

Main host(s)

Alders, amabilis fir, basswood, beeches, birch, common horsechestnut, elms, Engelmann spruce, grand fir, hemlocks, london plane-tree, maple, oaks, poplars / aspens / cottonwoods, Rocky Mountain Douglas-fir, scots pine, Sitka spruce, subalpine fir, tulip-tree, western redcedar, western white pine, white spruce, willow

Secondary host(s)

American chestnut, ashes, butternut, eastern hemlock, eastern white-cedar, hickory, western hemlock

Photos

Denis Lachance

André Carpentier

Advanced decay caused by G. applanatum

Al Johnson

Fruiting bodies on Populus spp. Note the brown spores on the tree bark and upper surface of some of the fruiting bodies

Eric Allen

Ganoderma applanatum, the artist's conk, on a dead maple.