Important Wood Decays

Here are simply lists, with annotations, of some important decays with a focus on North America. They are in 3 categories: stem decays of living trees, root and butt rots, and primarily saprobic decays (i.e., decaying dead trees).

Stem Decays

Some important decays of stems of living trees
FungusDecay typeName of decay, disease, or common name of fungusCommon hostsComments
Dichomitus squalenswhite pocket rot (often indistinct pockets)(disease) red ray rotPinus ponderosa = Polyporus anceps; enters branch stubs; decays heartwood in radial streaks; FIDL; Rocky Mountain Region Field Guide Entry
Echinodontium tinctoriumwhite rot(fungus) Indian paint fungus;
(disease) rust-red stringy rot
many non-pine conifersenters branch stubs, dead twigs; one conk represents very extensive decay
Fomitopsis officinalisbrown rot(fungus) quinine funguswas once a major source of medicinal quinine
Inonotus glomeratuswhite rotAcer spp. (maples), Fagus grandifolia (American beech)small clinker "conks" in stubs that won't heal
Inonotus obliquuswhite rot(fungus) clinker conk; cinder conkBetula spp. (birches)large clinker "conks" are sterile; real conks appear after tree dies
Phellinus igniariuswhite rot(fungus) false tinder fungus;
(disease) white trunk rot
many hardwoodsvery common and important in eastern North America and Europe
Phellinus tremulaewhite rotwhite trunk rotaspens (Populus spp.)very similar to Phellinus igniarius; FIDL
Porodaedalea piniwhite pocket rot(disease) red ring rotmany coniferspunk knots
Stem decays of spruce and fir in the Rocky MountainsFIDL
Stem decays of Abies spp. (true firs)FIDL

Root and Butt Rots

Some important decays of roots and butts of living trees
FungusDecay typeName of decay, disease, or common name of fungusCommon hostsComments
Armillaria (many species)white rot(fungus) honey mushroom;
(disease) Armillaria root rot; shoestring root rot
many hardwoods and conifers, depending on the pathogen speciesoften associated with stress in hardwoods; FIDL
Echinodontium tinctoriumwhite rot(fungus) Indian paint fungus;
(disease) rust-red stringy rot
many non-pine conifersenters branch stubs, dead twigs; one conk represents very extensive decay
Fomitopsis officinalisbrown rot(fungus) quinine funguswas once a major source of medicinal quinine
Inonotus glomeratuswhite rotAcer spp. (maples), Fagus grandifolia (American beech)small clinker "conks" in stubs that won't heal
Inonotus obliquuswhite rot(fungus) clinker conk; cinder conkBetula spp. (birches)large clinker "conks" are sterile; real conks appear after tree dies
Phellinus igniariuswhite rot(fungus) false tinder fungus;
(disease) white trunk rot
many hardwoodsvery common and important in eastern North America and Europe
Phellinus tremulaewhite rotwhite trunk rotaspens (Populus spp.)very similar to Phellinus igniarius; FIDL
Porodaedalea piniwhite pocket rot(disease) red ring rotmany coniferspunk knots
Stem decays of spruce and fir in the Rocky MountainsFIDL
Stem decays of Abies spp. (true firs)FIDL