This fall a 61" dbh willow oak on a property I have been working with for 8-9 years had several Polyporus mushrooms (probably hen of the woods, but they were a bit decomposed when I saw them) growing at its base. Since the tree is the biggest one on the site, looks great, and has never had any such problem before, we arranged for an Airspade to be used to remove soil within 24-36 inches of the base of the tree. We found that the roots from which the mushrooms emanated are 1-2 inches in diameter, are obviously decayed, and were rather weak to begin with. They are only 2-3 feet long and are growing on top of masses of roots that are 3-8 inches in diameter. No decay is evident in these larger roots - they look just fine, but I did not drill them. I speculate that the weak roots declined in previous years' drouth and then became infected; the Polyporus showed up this year after excessive rainfall. (The tree grows on a natural floodplain at the edge one of the last remaining wetlands in the DC area.)
Question is, what to do? Cut out the infected roots? If so, where (since there is no collar evident where they join larger roots)? Not knowing what to do, I am inclined to leave them alone, but what do all you sages think?

Reply to post by Ed Milhous, on November 25, 2000 at 08:54:16:

I guess the key question is how effectively the tree will isolate or compartmentalize the decay in the smaller roots and keep it out of the larger ones. I'm no pathologist and I don't have the answer. I'd GUESS that it might be desirable to minimize the carbohydrate source and get rid of the exposed, decaying roots, but avoid wounding near the larger roots since there is no obvious collar.

Is there any evidence that this has happened before and that the tree has sucessfully "shed" such smaller roots? Or that this is a "newish" maturity phenomenon?

Are the 8" roots the largest, 1st order roots emerging from the flare? Or are they branches from the 1st order butress roots? I'd guess we'd wonder whether relative separation from 1st order roots would slow the advance of decay into them or the trunk itself. I'd also guess that the "massing" of 3-8" roots could be significant in future risk analysis... if you employ the protocols that consider the %age of roots decayed.... say 3 decayed roots out of 8 is worse than the same 3 out of 12 or 15.

Are you in the wetland soil or the upland soil? Are the potentially damaged roots in tesion or compression relative to prevailing wind, lean or load. Orientation realtive to target?

So much we don't know about what all this means. See you in Newport?

Reply to post by Scott Cullen, on November 25, 2000 at 08:54:16:

The affected roots are on top of the main buttress roots, where the latter just have become horizontal; they are branches off these main roots. There were at least five mushrooms, distributed around the trunk, but none grew from a large root. The soil surface is about 24 inches above high tidal waters in the marsh, which is about 100 yards away; definitely 100 year floodplain. On the side of the tree toward the marsh is National Park Service forest; on the other sides is open lawn area, used somewhat less than intensly.
I am concerned about cutting off these infected roots. Will spread of fungus into the larger roots occur more readily/rapidly if I cut them off, or if I do not cut them off? Can the tree do a better job of limiting damage than I can?

Reply to post by Scott Cullen, on November 25, 2000 at 08:54:16:

PS: Yes, see you in Newport

Reply to post by Ed, on November 26, 2000 at 07:40:15:

Ed, I've found several Polypores this fall, too. I have one identified as P. frondosus. the other is similar, but with thicker caps, lighter brown in color. Have you found any good sources for identification of the Polypores (online or books)? Bryce Kendricks CD, The Fifth Kingdom, doens't eal much with non-gilled, except to include a gallery of photos, but none of the ones I have.

BTW, this CD is available for about US$80 or $85, and is basically a textbook on mycology, coupled with a tremendous search engine for details of the Pacific Northwest gilled mushrooms and some other types. Runs on Windows & Internet Explorer.

http://www.pacificcoast.net/~mycolog/fifthtoc.html

Reply to post by Russ Carlson, on November 26, 2000 at 10:50:44:

There aren't too many mushrooms I will claim to have identified if ID is truly significant. Reference materials are so confusing, what with name changes, and the mushrooms are so changeable, too. (I regret now not taking a very popular class on edible mushrooms with O.K. Miller at Virginia Tech.) The Fifth Kingdom does look interesting.

Reply to post by Ed, on November 26, 2000 at 22:44:39:

Here is another resource you might like to browse.

Reply to post by Mark Goodwin, on November 28, 2000 at 08:16:18:

Got that one on my list already.

The Fifth Kingdom is a very good resource, both for browsing and searching for an ID, and for learning mycology. It is based on Kendrick's course text. Windows only, but runs well on VirtualPC.