That's going to be trouble...

When assessing a tree's risk of failure we must sometimes look for the finer signs and symptoms that may indicate a tree's potential to fail.  The convenience of giant decay conks, broken roots, and huge decayed cavities may not always be evident on a tree that presents a high risk of failure.

Let's look at some pictures of a tree that from a distance may seem fine, but upon closer inspection proved to be cause for alarm.

Notice the soil heaving on the tension side of the lean.

Saw dust or frass present on several areas around on the lower trunk.  When sounded with a hammer decay was detected.

Small armillaria fruiting bodies protruding from the root flare of the tree on the tension side of the lean.  Armillaria root rot is a serious structural root decaying fungus which results in a white rot.

From a distance this willow oak has a perfectly green and balanced canopy, and is in a beautifully maintained yard.  Upon closer inspection the tree described above displays some serious evidence of strength loss.  Further proof that when walking a property, we can take nothing for granted.

Armillaria: Tree Failure

Armillaria, or honey fungus, is a genus that covers several species of soil born root decay fungi.  The common name is derived from the yellow-orangish mushrooms depicted in the pictures below.  Armillaria causes a white rot, which like Inonotus (as described in an earlier post) begins by breaking down lignin and in advanced stages breaks down cellulose and hemicellulose.   

While white rots are usually described as slow moving decay organisms, Armillaria is noted as being more aggressive in its attack on tree structure.  Armillaria gets its other common name 'black shoe string fungus' from the black mycelial fans it puts out to devour wood.  Unlike other structural root decay fungi, Armillaria also can affect the vascular system of the tree, so early signs of infection may be noticed by a decrease in tree vigor and poor tree health.

The pictures below show what happens to trees in advanced stages of Armillaria infection.

The yellowish orange mushrooms of Armillaria protruding from the bark on  the lower stem of the tree.

Notice the tell tale black mycellium penetrating the wood fibers of it's victim.