Pix would make for fewer WAGs.

Dan

First thing I would do is to contact my local county extension office and see if they could send someone out to look at the problem. If they couldn't/wouldn't send someone out to take a look (or maybe even if they did), I'd contact a certified arborist (see link below) and have them evaluate the situation.

Are the affected trees in a single area or spread throughout your property?
Are there more of the same type of trees in the area that don't seem affected?
Did your area see severe droughts the last couple of years like we've had here in Tennessee?
When did you first start to notice trees in decline?
Are there mushrooms around the base of your trees?
Is there shoestring root rot visible in any of the rotten stumps?

I'll go ahead and make a Weegieboard Attributed Guess based on the very very limited info above. Check out Armillariellia mellea. It could just as easily be other things, but that's as good of a guess as any at this point.

Here is a link that might be useful: Find an ISA Certified Arborist

Googling Armillaria mellea will yield better results. ;o) They are yummy in many dishes, too.

I doubt Extension staffing is such that they themselves can go out, they may make a recommendation.

And brandon cuts me off at the knees again, as I was looking for more info before recommending a certified arborist (gotta keep the peeps working!). Nonetheless, always good to try and narrow things down.

Dan

That's what I get for copying and pasting from the first google link I come to, without checking it out. I googled 'shoestring rot' to keep from having to remember how to spell it, and "Gogel's" first entry is a misspelling.

Dan, I should have learned from you and just called it AM. (-;

P.S. .....

"I doubt Extension staffing is such that they themselves can go out, they may make a recommendation."

Depends on the location. It's not uncommon at all in some places. Just depends on the program, their policy, and their work load.

If Sandy makes it sound like a widespread botanical pandemic, chances are better of getting someone from the extension office out to look. Of course then there's the boy that cried wolf thing....

Another good reason to call the extension office is to find out if this is a trend in the area.

Has there been ANY kind of construction activity in the area in the past several years? Any change to the grade, even though it may seem insignificant to you, or too far away to impact your trees?

Ok, let me clarify things a bit. First off, I was wrong to say these are swamp chestnut oaks. I had keyed them several years ago as chestnut oaks, Quercus prinus, but had somebody recently contradict me and say the were SCOs. I double checked my findings against several sources and confirmed they are CO.

Secondly, since I'm a Master Gardener Volunteer with our local extension office, I've already "contacted" them. I've discussed this with our agent on a couple of occassions and he (a plant pathologist by training) hasn't heard about anything specific to these trees. I haven't taken him any samples yet since root samples (which he wants) are difficult to get from 2-3' diameter oaks. That's on my list of things to do.

Brandon, the trees are spread throughout our property and adjacent properties (about 50 acres total area) and there are many apparently healthy COs among them. But these looked healthy until they started dying. We've had several summers of moderate drought but not severe. We started noticing them dying about 3 years ago. I've seen a ganoderma lucidum near a couple of the trees. I hadn't thought about it but they are a cause of root rot in some oaks. However, the way these trees decline is not indicative of this particular fungus. Another tree that was blown down during a hurricane a few years ago had several of the armillaria mushrooms (I'm not 100% sure which one) growing near the base and they continue to come back, I assume still getting nourishment from the remaining roots.

Oh! Oh! You are wonderful! One of the pictures I took of the most recently cut down tree showed the black "strings" typical of shoestring root rot! I haven't seen the fruiting bodies near these trees but this may be the clue I need. I'll go find that particular piece of wood and get some samples for examination.

Even though I've been a MG for 10 years, I still have so much to learn. Thanks for putting me on the right path.

Oh, and Rhizo, no there has not been any construction or change of grade near these for many years. We've been at this property since 1979 and the trees are scattered about so widely that the minimal disturbance from lawn care can't account for this.

I don't have a definite answer from this discussion but you've certainly given me direction. Thanks to you all!

Sandy

Click on this thumbnail for a full picture. Is this what I think it is?
{{gwi:382176}}

Dan, I should have learned from you and just called it AM. (-;

AFAICT you're learning PDQ how to do TLAs.

Dan

Sandy, It's hard to tell for sure, but it does look like a strong possibility. There are a few good pictures of AM (-; on Google Images. Try that and compare with what you see.

Sandy should have a number of pathology texts at the office that have clearer fotos than the one above for ID. Keying fungi is difficult anyway, and just hyphae is tough, but having a text with the indicators there will help. My Arboriculture by Harris et al is some help, not much & IME pathology texts are best.

Dan