Laminated Root Rot

Disease

High Threat

Affects: Douglas fir (primary), grand fir, mountain hemlock - the dominant conifers of the PNW

Photo: USDA Forest Service / United States Department of Agriculture (CC-BY-3.0-US (Bugwood))

Identification & Biology

Soil fungus (Phellinus sulphurascens) that spreads through root contact. Infected trees show reduced growth, thinning crown, and eventually blow over in wind because roots are rotted. Spreads slowly but persistently through stands.

Current Status

Endemic in PNW forests. The most damaging root disease in the region.

States affected:

Oregon Washington

What Homeowners Should Do

If a Douglas fir falls or shows lean/crown thinning, have roots assessed. Adjacent trees connected by root contact may also be infected. Stumps of infected trees continue to spread the fungus - consider stump grinding.