Conifer Root Rot Fungus

Heterobasidion annosum

On conifers, most often on spruce roots, stumps, windfalls. Spring, summer, autumn (winter).

Fruiting bodies annual or perennial, 5-20 cm across, of irregular shape, solitary or arranged in overlapping tiers, spreading, with the margins raised from the substrate, or in the form of flat caps attached to the substrate by the side; surface uneven, concentrically furrowed, from yellowish-brown to dark blackish-brown, the margins paler. Hymenophore white, when old yellowish, cream, brownish. Flesh corky, yellowish, with a faint mushroom smell. Grows in forests on roots, snags, stumps and windfalls of spruces, pines and other conifers, also occurring on deciduous trees.

Causes a white mottled rot of the roots and butt; a dangerous parasite, especially of spruces.