White spongy trunk rot of hardwoods

• French disease name: Carie blanche spongieuse du tronc des feuillus
• Pathogen name: Spongipellis delectans (Peck) Murrill
• Class: Aphyllophorales
• Partial list of synonyms:
  • Polyporus delactans Peck
  • Tyromyces delectans (Peck) J. Lowe

Distribution

Canada

Damage, symptoms and biology

The annual fruiting bodies consist of one or more overlapping caps. They lack stalks and are often hoof-shaped. The upper surface generally has a felt-like appearance; it is initially white, turning yellowish brown. The white underside turns yellow or light orange. It often grows on old trees where it is quickly replaced by other decay fungi, but it is found primarily on stumps and dead trees. It infects live poplars more easily.

Significant losses in wood strength occur in trees with advanced decay.

Other information

Decay occurs mainly as a trunk rot, rarely as a butt rot, in both living and dead trees. In living trees, decay is usually confined to the heartwood. Infection appears to occur through branch stubs or branch scars.

Canadian Forest Service Publications

White spongy trunk rot of hardwoods

Information on host(s)

Main host(s)

Elms, maple

Secondary host(s)

Alders, basswood, beeches, oaks, poplars / aspens / cottonwoods

Photos

Bill McNaughton

Fruiting bodies of S. delectans on a cottonwood stump

Rollie Banyard