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By R. S. Hunt and D. E. Etheridge
Decay caused by root-, butt-and trunk-rotting fungi (Basidiomycetes) is responsible for an estimated annual loss of timber in British Columbia that exceeds 10 million cubic metres. Obviously, accumulated decay vol-umes are staggering. The bulk of this volume loss is due to heart-rot in trunks of living trees.
Among the most destructive of the heart-rots in British Columbia forests are those caused by true heart-rotting fungi. These are so-named because the characteristic decay is usually confined to the true heartwood. They are the only species that consistently produce fruiting bod-ies on living trees. They may also pro-duce sterile structures known as "punk knots" or "swollen knots." Unlike other heart-rotting fungi, these species never occur as primary invaders of slash and dead material, or cause damage to timber in service, although they may continue to develop in fresh-ly cut logs in the forest for varying periods. They also differ in their mode of attack, since mechanical injuries do not appear to be the principal infection courts for these species. Control mea-sures designed to reduce wounding of trees, or as protective treatments to scars, are therefore unlikely to prevent infection by these fungi.
Only the true heart-rots will be dealt with in this leaflet. There are four species of true heart-rotting fungi in British Columbia: the Indian paint fungus (Echinodontium tinctorium (Ell. & Ev.) Ell. & Ev.) and the ring scale fun-gus (Phellinus pini (Thore: Fr.) A. Ames) on conifers, the false tinder fungi (P. tremulae (Bond.) Bond. & Poriss. in Bond.) on aspen, and P. igniarius (L.: Fr.) Quél. on other hardwoods.
For more information, see the True heart-rots of the Pacific region Forest Pest Leaflet in the Canadian Forest Service bookstore.