It's water stress. Not enough water getting to the top of the tree.

Always be cautious when purchasing a woody plant. If they've been in the garden center all season, they're likely rootbound. End of the season specials are typically rootbound.

If you're considering replacing it, do it sooner than later. The longer you keep it the more reluctant you will be to let it go.

Good diagnosis I agree.

Quercus x sternbergii is one that isn't available (I don't think) but might be that Oak that 'takes away the pain'! ;-)

Author Guy Sternberg per an email:
"It's a nothospecies -- a stabilized hybrid of Q. shumardii x Q. buckleyi that's found naturally in a narrow band in Texas where the two species are barely sympatric. It was named for me by Professor Reinhold Luebbert of Germany in his World Compendium of oaks. Expect medium size pyramidal habit, small leaves and acorns, and brilliant scarlet fall color. " (Photos on the Net) -- I had two plants of this but my hoophouse froze. I'm going to ask for some acorns when I go to visit Guy hopefully soon.

Dax

Thanks. The leaves aren't at the top. They are in the lower part of the tree... Watering it may be tough since it's surrounded by fence (in the corner of backyard) 8 feet spacing... Next door never waters yard. In the back, it's just empty lot. I do water deeply every week or so during the summer if no rain though. All of other trees including shantung maples look very healthy in rocky limestone soil. Bur came from Lowe's so I wouldn't be surprised if it had major girdling problem because I have seen others from lowe's when they were pulled out of ground. They both had big ball of circling roots... Oh well. That was my very first tree I planted. Didn't know any better back then.

Dax,

Come down to Texas this fall. Plenty of acorns from both trees! I love Q. Buckleyi. Probably my favorite oak tree. I collected a bunch of acorns from it but unfortunately they germinated in the fridge way too early. Need to do a better job of storing them over the winter. You can tell them apart by looking at their buds in fall/winter. Q. Buckleyi has buds that is all equal size (co-dominate). That's why they tend to have multiple trunks in the wild. Q. Shumardii has larger central bud while the lateral buds are smaller. I can also tell which is which that is not suitable for alkaline soil. if the buds are 1/8" of an inch, they will suffer badly in the alkaline soil. It's common around here unfortunately. Buds need to be at least 1/4" to do well here. My neighbor directly across the street has the wrong red oak and it's so ugly. All yellow leaves that are turning brown. Have to see that every day out of window. I provided info about it to them and they haven't done anything for 2 years! Getting worse every year... Damn shame. I need shade from there (hot afternoon sun). Not only that their next door neighbors somehow killed nice sized lacebark elm over last weekend! All leaves are brown right now... Oh well.

Gonna be tough digging that bur oak out...

Lou,
I'd guess oak anthracnose. Mainly affects members of the white oak group
A couple of weeks back, former coworker asked me to swing by and look at a young bur oak I'd given her 6 or 7 years ago. Leaves on lower portion of the tree were similar to what you've posted, though a significant number also had distinctly demarcated areas of browning/death contained within areas between veins, in addition to myriad little round brown spots. Significant numbers of leaves had curled leaf margins, as well. Characteristic of anthracnose.
We've had a pretty wet spring/early summer, and conditions have evidently been prime for anthracnose, though I've not noticed any on my trees here at the house.

Lucky,

It does look like oak anthracnose but it doesn't seem like that's what is causing it (very dry since April) or may be due to stress from root girdling. Who knows? At least there's always a very nice looking bald cypress that I am growing in 15g roottrapper right now to replace bur oak. At least it can produce nice fall color...

Lou:

I stumbled on this post....

Don't want to sound like I'm butting in here, but the stipling/thinning of the leaves looks like lace bug damage.

My bur oak gets this almost every summer. It's got them right now.

Lace bugs are a bit like aphids. Their damage is cosmetic and nothing serious.

I know that you help out others in your community, so that is why I responded.

A hand lens can reveal very small insects.

(An example of a plant that is notorious for lacebug problems is Pyracantha -- to the point that it causes a dicoloration/chlorotic appearance and thinning of foliage etc)