Tomentosus root rot, Inonotus tomentosus,

Fig. 138 Fruiting bodies.	Fig. 139 Infected young spruce tree. Note distress cone crop and reduced terminal growth.	Fig. 140 Thin crowns of infected older spruce.	Fig. 141 Cross-section of infected stump.

Distribution: Throughout B.C. particularly in spruce stands of the central and northern interior.

Host Susceptibility:  Interior spruce is highly susceptible. Moderately susceptible species include: lodgepole pine, western hemlock, Sitka spruce, Douglas-fir, and sub-alpine fir. Resistant or immune species include western redcedar and broadleaf species.

Signs & Symptoms: Tomentosus root rot often causes small gaps in stand canopies that can coalesce into larger openings, within which lay randomly-oriented, downed trees with decayed roots. Symptoms include chlorotic thinning foliage, reduced shoot growth, and distress cones. Tomentosus root rot causes a pink to red-brown stain in wood, which progresses to a salmon colour, eventually forming a honeycomb-like, white pocket rot. This pattern progresses from the interior of the root outwards. Decay can be found 1 to 2 m up the bole. Fruiting bodies are produced in the late summer directly from infected roots, and appear as small mushrooms (<10 cm across), which are leathery, velvet topped, and tan to brown, with a porous underside.

Damage: Tomentosus root disease is the most prominent root disease in central and northern BC. Juvenile trees die quickly. Older trees suffer extensive butt rot leading to increased susceptibility to windthrow and insect attack. Tomentosus spreads primarily through root contact and can survive in infected large stumps for decades.

Can Be Confused With: Symptoms are similar to other root diseases, bark beetles, and abiotic problems. If mature, standing dead trees exhibit boring dust or bark beetle galleries, check for signs of root disease. Unlike other root diseases and the decay caused by Phellinus pini, tomentosus produces a distinct honeycomb pattern of advanced decay, which is readily apparent in cross-sections of broken roots or stumps.

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Contact Tim Ebata if you have comments on the presentation of this information.

BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated February 18, 2002