This is Laminated Root Rot

We have our share of Phellinus (Poria) weirii -- Laminated root rot.

Laminated root rot is the cause of the high percentage of dead fir snags in a few small areas of our property.



This tree fell during the winter and I discovered it in the spring. Notice how small the root wad is, compared to what a healthy blow-down would have. Another tree fell about 50 feet away.

 

Leaning fir trees often indicate weak roots. Butt rot is obvious here: the fir is slowly uprooting and has already lost its top. It's surrounded by fir snags and large living fir trees with weeping trunks.

This is considered to be the most damaging root disease in the Pacific Northwest, as it kills the greatest concentrations of trees in the areas where it is present. Sometimes called butt rot, this disease is most tragic because it kills all Douglas Fir (Pseudotsuga menziesii) in an expanding radius and makes it impossible to grow that species again in that location.

Root rot is most obvious where there is a patch of jack-straw trees, snags and leaning trees. Dead fir saplings among fir snags are a pretty sure sign. Look more closely for weeping tree butts, fading  crowns and firs that fall by uprooting -- particularly if the root wad appears unusually small for the tree.

The disease is spread by root contact between an infected tree and healthy ones. The disease kills susceptible hosts by either predisposing them to windthrow by rotting the major roots, or by destroying their ability to take up water and nutrients. Saplings and small poles are usually killed quickly, while older trees may confine the fungus to a small number of roots or to the butt log and survive for many years.

The fungus may remain viable in stumps for 50 years and thus infect regeneration, although it typically takes 10 to 15 years for roots of the new trees to make contact.

There is no treatment for root rot. The only recourse is to cut all trees of that species in the infected area, and one more tree's width (drip line radius) around the circumference of that area to be sure. Sadly, this sometimes involves clear-cutting a sizable area. Our neighbors just over the ridge did that, although I'm not sure they know it, maybe the logger made that decision for them. The timber generally is merchantable.

If we postpone action, the area only gets larger. In one area we cut about an acre of infected fir trees, but we were able to leave several very tall, healthy Ponderosa pines.