have you ever had your soil tested ....

talk with your county extension office.. about such in regard to the county soil ...

in the mean time.. do you see any correlation between who has their lawn sprayed.. and who doesnt????

and finally.;. where are you.. big town ..

ken

tugg01, I note that the leaf in the foreground is half green and the other half - less so.
This Person has a similar problem with his marijuana plants; and (s)he has tried all the remedies that should have worked; but none of them did.
I would start at the tip of a "yellow" branch and work backwards to the point of attachment to another branch or the trunk. Look for any sign that would indicate that conducting tissues have been compromised - a canker, mechanical damage, borer activity and the like.
If you find nothing worrisome, then look at ground level on the same side of the discoloration. Very often, but not always, something done to one side of the root system will show up in the leaves on the same side.
Incomplete fertilization, or inattentive application of weed and feed to the turf can show up as a discoloration or other adverse signs on shrubs and trees in the landscape. Other causes may be fungi or mechanical damage.

Chlorosis of Pin Oaks is most often traced to a soil that has too high a pH. Most Oaks, but Pin Oaks especially, evolved in soils that were wetter and had more organic matter then many they are growing in today. You are at a disadvantage since, as I recall, AgCanada does not do soil testing. However, they should be able to direct you to a lab that will.

I live in the interior of BC, Canada. A rural area with forest nearby. I haven't done a PH test yet. I did a more thorough inspection of the tree and added this picture of what I found.

Looks like scale. Here are 3 types of scale that oak get from a Penn state book:

Woody ornamental Pest management
insects and mites, 49
Golden oak scale: Horticultural spray oil can be applied as a dor- mant treatment. crawlers may be managed with formulations of acephate, azadirachtin (ornazin 3% ec only), bifenthrin and imidacloprid, buprofezin, carbaryl, chlorpyrifos (Dursban 50W only), cyfluthrin, cyfluthrin and imidacloprid, dimetho- ate, dinotefuran, flonicamid, horticultural oil, hydrophobic extract of neem oil, imidacloprid, insecticidal soap, lambda- cyhalothrin (Demand cs, scimitar cs, and scimitar gc only), methidathion, and thiamethoxam. Marathon 1% g and Marathon 60 WP are labeled for use only on plants grown in containers, flats, benches, or beds.
management hints: select and apply horticultural spray oil according to label directions. this scale insect makes small pits in the bark on twigs. crawlers are active in mid-May. repeat applications may be needed. (p. 352)

Oak kermes scale: Horticultural spray oil can be applied as a dormant treatment. crawlers may be managed with for- mulations of acephate, azadirachtin (ornazin 3% ec only), bifenthrin and imidacloprid, buprofezin, carbaryl, chlorpy- rifos, cyfluthrin, cyfluthrin and imidacloprid, dinotefuran, flonicamid, horticultural oil, hydrophobic extract of neem oil, imidacloprid, insecticidal soap, lambda-cyhalothrin (Demand cs, scimitar cs, and scimitar gc only), malathion, methi- dathion, and thiamethoxam. Marathon 1% g and Marathon 60 WP are labeled for use only on plants grown in containers, flats, benches, or beds.
management hints: select and apply horticultural spray oil according to label directions. crawlers should be managed in mid-May. repeat applications as needed. (pp. 364, 366)

Obscure scale: crawlers may be managed with formulations of acephate, azadirachtin (ornazin 3% ec only), bifenthrin and imidacloprid, buprofezin, carbaryl, chlorpyrifos (Dursban 50W only), cyfluthrin, cyfluthrin and imidacloprid, dinotefuran, flonicamid, horticultural oil, hydrophobic extract of neem oil, insecticidal soap, lambda-cyhalothrin (Demand cs, scimitar cs, and scimitar gc only), and methidathion. management hints: select and apply horticultural spray oil according to label directions. egg laying and crawler activity occur over an extended period. sprays may be applied when crawlers are first active, from mid- to late July through early august. crawler sprays may need to be applied into early september when an infestation is severe. (p. 384)

The spray timing is for Pennsylvania, Zone 6

not being one with the attention span.. to actually find the crawlers that cant be seen with the naked eye.. and always thinking about such.. a few weeks after they are no longer in that stage ...

i usually default to a systemic like bayer tree and shrub ... one application.. and yoru problem is solved.. and in my experience.. for all but EAB.. they will not come back ...

at that point.. the issue is whether the cost is out weighed by the size of the tree.. and it would be cheaper for me to simply cut down the tree and be done with it..

how that all flushes out in canada.. is beyond me ...

the scale.. at that level of population.. are sucking the life out of that tree ... and if you have had no pH problems before.. and others in the area dont.. then my gut tells me it is NOT a soil issue ... but my gut has lied to me before ...

you might want to contact a local pest management company for a local opinion as to your options....

ken