Fomitopsis officinalis (Vill.:Fr.) Bond. et Sing.

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Western larch, ponderosa pine, and Douglas-fir are the most common hosts. Engelmann spruce, true firs, and western hemlock are also known to be infected.

Distribution. – Idaho and Montana west of the Continental Divide.

Damage. – Heartrot of the stem. A single conk usually indicates complete cull.

Identification. – The decay is common only in a few old-growth stands. Conks are large, as much as two feet long, hoof-shaped or columnar. They are soft, yellow-white when young, soon becoming white and chalky throughout. The decay is brown, cubically cracked, with thick white felts in large cracks. The taste of both conks and felts is bitter and distinct for this species.

Similar damages. – Phaeolus schweinitzii also produces a brown cubical decay in these tree species. Mycelium felts, when present, are very thin and resinous. Fomitopsis pinicola also produces a brown cubical decay but the mycelium felts are thinner than those of F. officinalis and lack the bitter taste. F. pinicola decay seldom occurs in live trees.

Link to Table 1 – Comparison of Common Heartrots in Species Other Than Western Redcedar

Link to Images in Forestry Images

References.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv.,Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Bega, R. V. 1978. Diseases of Pacific Coast conifers. USDA For. Serv. Ag. Hndbk. No. 521, 206 p.

Boyce, J. S. 1961. Forest Pathology. McGraw-Hill Book Co., New York, NY. 572 p.

Hepting, G. E. 1971. Diseases of forest and shade trees of the United States. USDA For.
Serv. Ag. Hndbk. No. 386, 658 p.

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