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.

Compaction for the Sake of Grass?

One of my favorite calls is from a contractor, in this case a very large landscape company, that has been busted by the city for failing to do any tree protection.

So our assignment is to decompact areas leveled for the sake of sod installation.  Our medium is compacted red clay.  If you have used an AirKife or Airspade in this scenario then you know attacking glazed clay is futile.  I go about it by finding an area where I can penetrate the soil as close to the severe compaction as possible.  Once deep in the soil,  I angle the air tool under the glazed area.of compaction.  By repeating these steps around the area, it eventually begins to break up in to large peds.

In the past I would try to break up peds into finer soil, but after having gone to Jim Urban's 'Up by Roots,' I now try to preserve peds.  These peds are an essential part of soil structure, especially in heavy clay soils.  Of course, I then mix in composted organic material to help maintain soil structure and improve nutrient holding and water holding capacity.

An argument may by made that August is not the best time to be using an AirKnife in such a large area, as it may dessicate fine roots.  In the face of progress, there are only so many options.