Yellow Root Rot
Perreniporia subacida
3 host plants · Fungal
Last updated
Western red cedar (Thuja plicata) and other conifers develop white-to-cream conks on roots and root crotches from Perreniporia subacida. Advanced decay creates stringy fibers with small black flecks. The fungus typically affects suppressed or weakened trees. Damage has been minimal; no treatment techniques are established. Favor resistant species when thinning or replanting infected sites.
Damage has not been serious enough for treatment techniques to have been developed. Remove affected trees during harvesting operations.
Quick Reference
Management
Root infection year-round but active Oct–May. Disease progression very slow (10–20+ years). Internal decay advances without visible symptoms for years. Visible decline typically summer (heat/drought stress). BBCH 10–89.
Root contact with infected wood and mycelium. Most active in cool, moist soil (50–60°F, Oct–May). Stress conditions and poor drainage favor pathogen spread and disease expression.
Cultural Controls
- Damage has not been serious enough for treatment techniques to have been developed.
- Remove affected trees during harvesting operations.
- Favor tree species not showing damage when thinning or planting sites with yellow root rot.
- References Hadfield, J.
- S., Goheen, D.
- J., Filip, G.