Heterobasidion annosum is widespread in forests in the United States and is responsible for the loss of one billion U.S. dollars annually.

Later, it was found to be linked to conifer disease by Robert Hartig in 1874, and was renamed Fomes annosus by H. Karsten.

The fruiting bodies of the fungus, which are also known as basidiocarps, are normally brackets which are whitish around the margins and dark brown on the uneven, knobbly upper surface.

[1] The fertile surface of the fruiting body is white, easily bruising brown, and has barely visible pores, with 3-4 per mm.

These gaps affect the moisture and sunlight available, altering the habitats for plants and animals on the forest floor.

The H. annosum infections cause an abnormal change in structure in the roots that climbs up to the butt of the tree.

A landscape scale symptom is the rings of dead trees in various stages of decay and death, with the oldest at the center and progressively younger moving outward.

The white rot fungus found in the roots is the sign of telling whether the tree has been affected by H. annosum.

Water agar could be used with infected host tissue to produce conidiophores which a simple or branched part hypha of a fungus to eliminate H. annosum.

Chemical methods include prophylactic stump treatment with a solution of urea immediately after the infection.

This protects the stump by hydrolysis of the compound by the enzyme urease in the living wood tissue, which results in formation of ammonia and a rise in pH to a level that H. annosum at which mycelia are unable to survive.

Currently, a number of fungal species such as Phlebiopsis gigantea, Bjerkandera adusta and Fomitopsis pinicola have been tested on stumps as competitors and antagonists against H. annosum.