Rot, mould or fungus identification and concern
I have an old growth Maple that was suffering from numerous problems (insects, Wood Peckers, fungus) that I was planning to have removed this month but it fell over during a storm two days ago.
The exposed trunk revealed the tree had a severly rotted core and what appear to be "webs" and small bore holes but no visable signs of active insects. The broken branches seem to also exhibit internal rot.
I would like to replant in the same location with either Chinese Pistache or Shumard Red Oak but am concerned that whatever the root cause (no pun intended) is, the soil would need to be "sanitized" first to prevent contaminating the new tree.
I'd really appreciate some input on the probable cause of the problem and advise on whether I should be worried about soil contamination and how to treat it if it's an issue.
Edit: Turns out when the trunk was cut for removal, the center of the trunk was rotted up to about 4 inches above ground level. The roots were almost completely rotted away.
The rotting out of the center of the tree is actually a complex problem. As tree health declines from one cause, other causes move in. For example, as the insects start boring, the woodpeckers are drawn to the tree to feed on the insects under the bark. Likewise external damage to the bark allowed the fungus to establish, which may have drawn the insects, or the insects may have created the opening for the fungus. Lots of ways to get there, but they all wound up with a sickly, dying tree from multiple causes. Since a tree's life is just under the bark, some trees can be totally hollow and still alive. Just in a weakened structure.
For your particular problem, there are a number of heart rots that fit the description you gave. Mostly they are identified by the fruiting body -- the fungus. Heart rot usually occurs on older trees; it enters from external damage from pruning, insects, and even dead broken branches or animal damage. The fungal disease softens the internal wood. It is fairly common in older hardwoods and is difficult to prevent.
Your best defense is young healthy trees with proper care, water, nutrients and pruning. A healthy tree can fight off heart rot infestations by compartmentalizing them. The fungus spores are found pretty much everywhere. There are many fungi that cause heart rot .To identify exactly which heart rot your tree had would be to identify the fungi that caused it.
For more information of the fungi: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74109.html
Specific diseases of Maple, including several Heart rots: http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/maple-diseases
Replacing it with a young healthy tree and good culture and care should work.