Giant oak w/ rot in the center, dead of course

I just had a 100+ foot red (I think) oak taken down as it did not bud out this year and was clearly dead. I just moved to this property last spring and do not recall if it was healthy then or not, but I had a good tree guy here several times and feel sure he would have noticed if it was dead then. He said he would have noticed, anyway.
He was not on site for the final thud- just the workers remained, so I can't ask him about this today and thought someone here might have an idea.

The center of the stump and the first round above it have rot in the middle- clear through a 16" round. The margins of the rot are moist and soft, but not terribly so- just a bit. It smells... oakey, not rotty or bad in any way.
If it would help I can blow out the sawdust after it cools down and take a closer and/or higher resolution photo.

I am zone 6b eastern Kentucky and this tree borders old growth woods full of other oaks and hickory... mostly. If it is at all possible to identify what happened so I can prevent it occurring again I would be grateful. I absolutely hate losing old trees, and hate having to pay for it, too, although we will be heating with this one in 2010.

And thoughts or instructions on how to get this figured out are appreciated.

I would definitely enlist the help of your arborist if he's knowledgeable, or else your extension office to figure out what it was that caused the tree to die. Some of the things that could have possibly killed it could be transmitted to your other trees (or may have already been transmitted and they just don't have symptoms yet), and it will also impact what you can plant near where the oak was since there are many other non-oak species that are susceptible to some of the fungal diseases that can kill oaks.

If you have Acrobat Reader on your computer, here's a good article that talks about some of the various things that can happen to oak trees. It's from the Univ. of CA, but with the exception that you may not have sudden oak death in your area most of the other diseases should be relevant. http://ceventura.ucdavis.edu/newsletterfiles/Landscape_Notes11016.pdf

There's also another disease not covered in there (that I saw) called oak wilt which can kill trees rather quickly so that might be worth looking into as well. http://www.treehelp.com/trees/oak/diseases-oak-wilt.asp

I've contacted my county agent- she has been very helpful in the past, so I hope something comes of it.

Terrifying links, thanks!
I have 30 or more of these trees, and if taking each one down costs me $600.... wow.

Having a rotted area in the center of a 100 year old tree is not uncommon at all, and certainly not an indication of what might have killed it.

Decomposition in the center of otherwise healthy trees is normal. It is due to very natural occurrences (like the loss of a branch in a storm). The tree cordons off injured areas in several ways, known as CODIT. That stands for Compartmentalization Of Decay In Trees.

The area that is soft and rotting is walled off from the rest of the solid wood in the trunk in a radial fashion as one of the ways the tree protects itself. With a broken branch along a trunk, there is an "opening" via tree tissue for pathogens to enter the interior of that tree. Since trees don't bind their wounds (unless you're in Oz), they must do battle with potential pathogens by sacrificing older tissues to protect the remaining newer active parts of the tree. Thus, interior wood of the same age as the broken-off branch is walled off and sacrificed to infection or decay, but the borderline between that and the newer wood is reinforced against the pathogen moving into the newer wood area.

It helps to have pictures, and read it along with this information. Here is a site that does just that:

http://www.na.fs.fed.us/Spfo/pubs/misc/treedecay/pg12-19.htm

Dr. Alex Shigo promoted this information after years of studying forest trees and how their wood formed in these situations.

http://en.wikipedia.org/wiki/CODIT

You can google a lot more, but this essentially covers it. As far as what killed your tree, if you've disposed of most of the tree's parts by now, you've destroyed a lot of the evidence.

Oak Wilt, to which Red oaks are susceptible was found in Kentucky in 2007. Ask your Extension Agent. If it was Oak Wilt, you most likely will get other infected trees. However, don't jump to any conclusions. Look at other oaks in the nearby surrounding area. See what you can find.


http://www.uky.edu/Ag/kpn/pdf/kpn_1144.pdf

It's not disposed of- yet. If there is anything I should photograph or save, I can. The brush will be drug way back into our woods, and the wood will be split and stacked for burning in 2010. Right now it's in the middle of my rear lawn.

The rest of my oaks look ok, I guess. There are a few dead branches, but honestly they are all so crowded I can't see how it wouldn't happen. This portion of my land has never been cleared or cultivated- ever. I do see one tree nearby that has a runny spot on it.

Thank you everyone for all the links and thoughts. I've contacted my extension agent but she won't get back to me before Monday. I will try and educate myself in the mean time.

You might get out some of the branches and some of the chunks of trunk that were close to the bottom of the tree and take a look at how they look underneath the bark--I lost a Toyon tree a few years ago to either oak root fungus or a Phytophthora species, and the folks at the university sick plant clinic told me how to look under the bark and depending on what I saw it would tell me whether it was Phytophthora or Armillaria. I remember finding signs of both so I think I had a double whammy going on! I don't remember specifically what I was supposed to look for since this was a couple years ago, but I think the pdf article from UC that I posted has that same info and pictures. I'm not sure if oak wilt would have similar symptoms to look for or not.

Will do- thank you!

This the most current and comprehensive info on oak wilt. But, I caution, I'm not diagnosing your problem as Oak Wilt. More of an FYI to rule it out. At this pont it could be anything. Until you can get an opinion from the extension agent can you postpone moving the dead wood? No need to spread anything if it could be avoided.

http://ohioline.osu.edu/hyg-fact/3000/3306.html

He's moving it now- he only has weekends available and it will kill our grass if we leave it. I have not yet had a chance to look at the area underneath the bark.

And if it is the dreaded oak wilt, I would think root spread will do us in anyway. As I said all the trees are crammed in together. Trenching to try and control it would be out of the question- it's too late anyway as the tree is down, so if it is oak wilt I'm just toast, plain and simple.

I'll wait to hear from my agent before I get too distraught, and even then there's nothing I can do besides providing the most optimum conditions possible and hope for the best.
They list stress as a predisposing factor, and there was that terrible drought last year. I have been watering since last fall but the whole of last summer was likely very rough on them.

Fingers crossed that it's something else.

It's most likely NOT Oak Wilt and you are certainly right about the spread through root grafting. When you do get a diagnosis I expect to hear almost anything but Oak Wilt. People just need to be alerted to the possibility, though remote, in hopes of containing the spread.