Friday, October 31, 2014

Butt-rot Fungus

Weeping oak bracket
We found this large fungus on the base of a 14" tree stump.  Mark Bower identified it as Inonotus dryadeus, 'the weeping oak bracket.'  This is an inedible fungus (I suspect none of you were even tempted) which probably has the least-appealing common names in the fungal kingdom: 'weeping oak bracket,' 'warted oak polypore,' 'weeping polypore,' 'weeping conk'! Adding insult to injury, it is classified as one of the 'butt-rotting' fungi.

The term 'butt-rot' doesn't refer to a side-effect of tasting it but to its place in the woods.  It is found on or around the base (butt) of a tree, or in the case above, a tree stump.  It is found on oaks here as well as fir trees in the western states.  Michael Kuo describes it well.
"Inonotus dryadeus has a lumpy, irregular cap with a finely velvety, dull yellow surface and a margin that exudes droplets of amber liquid when fresh and young. It has a buff pore surface that bruises and ages brown, composed of very tiny pores."

Inonotus dryadeus is primarily a parasitic fungus although it can remain as a saprophyte after the tree is dead.  The food web depends on natural recycling and saprophytic fungi such as this are important decomposers of trees.  Saprophytes break down protein to amino acids, fat into fatty acids and glycerol, and carbohydrates into absorbable simple sugars.  When saprophytic fungi absorbs these, it becomes a food source for insects, starting a long trip up the food chain.
Weeping oak bracket closeup
Viewed really close up, a weeping oak bracket fungus is even more interesting.  I am frequently surprised how something plain or even ugly from a distance can have a strange beauty closeup.  The picture above, posted several days ago, shows the glistening liquid drops shining in the sun, beautiful if not appetizing.

There are many types of saprophytic fungi.  Some do primary damage to trees, others occur on wounded or damaged trees, or on dead trunks and roots.  The first sign of the root and butt rot fungus may be a dying tree or a blow down unearthing dead roots.  Our specimen above was on the stump of a tree that died a few years before, possibly because of the fungus.

Honey mushrooms between the trees
We found a lot of honey mushrooms, Armillaria mellea, growing along the ridge.  Some were at the base of trees but many were several feet away, probably growing on the roots which are shallow in the rocky glade-like soil.   The density of this population is probably not a good sign as the infestation can kill a weakened or even a healthy tree.

Honey mushrooms
I completed a Forestkeepers tree survey in the area and didn't show any signs branch dieback or discolored foliage.  A. mellea is a versatile species which can continue to grow on dead wood unlike many other species.  There are several large (14-19") long-dead oaks in the area and I am hoping it is just feeding on the remains of their dead roots.

A good source of information about root and butt rot fungi in general is found here.

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