Stringy Butt Rot

• French disease name: Carie filandreuse du pied
• Pathogen name: Perenniporia subacida (Peck) Donk
• Class: Aphyllophorales
• Partial list of synonyms:
  • Poria colorea Overh.
  • Poria homaena (Berk.) Cooke
  • Poria subacida (Peck) Sacc.

Distribution

• Canada

Damage, symptoms and biology

This fungus forms as a cream or brown crust on infected trees or snags. The pores are initially cream-coloured, turning yellowish brown over time. In conifers, it behaves like a root rot but also infects sapwood. In hardwoods, it is a saprophyte on sapwood.

The presence of fruiting bodies on living trees indicates up to 3 to 4 m of defect; on dead trees fruiting bodies indicate almost total cull.

Other information

Root and butt decay caused by P. subacida can cause significant losses and predispose infected trees to wind throw.

Canadian Forest Service Publications

Stringy Butt Rot

Information on host(s)

Main host(s)

• Amabilis fir
• Balsam fir
• Engelmann spruce
• Grand fir
• Sitka spruce
• Subalpine fir
• Western hemlock
• Western redcedar
• White spruce

Secondary host(s)

• Alders
• American chestnut
• Arbutus
• Birch
• Cherries / plums
• Juniper
• Larches / tamaracks
• Mountain hemlock
• Poplars / aspens / cottonwoods
• Rocky Mountain Douglas-fir
• Scots pine
• Shore pine
• Tamarack
• Tulip-tree
• Western larch
• Western white pine
• Willow

Photos

Advanced decay with mycelial mats caused by P. subacida

Eric Allen

Advanced decay with mycelial mats caused by P. subacida

Ray Foster

P. subacida sporophore on western redcedar

W.Poter