Black spots on Black Jack Oak Tree

[Okie Chick]

Hello. First time poster here.

We have a lot of Black Jack Oaks on our little property.
We live in central OK. Not the best oak tree there is, but it's what we have.
Been here 12 years, and we've lost 2 large ones and more recently (last year) 1 young one that was probably 20+ years old.
One day it looked fine, the next I it didn't look so well and within 3 days it was dead.
There's been no recent construction in the area -- other than when the addition was put in 20 yrs. ago.
Last night I noticed on this even younger tree these black spots.

We've only put down yard fertilizer -- and that was last season. We did have a early Spring treatment for weeds this year.

What is it stuff and what can we do to save it?

(The white on the bark is where the auto sprinklers/water hit the tree. That's been resolved.)
Thank you in advance!

 

[JeffGu]

That is Hypoxylon Canker... probably Hypoxylon atropunctatum... a fungus infection that usually enters where the tree has been injured. Once it gets to where you can see these spore masses, branches of the tree will already be dying and as you have already seen, it can kill the whole tree very quickly. It can only harm trees that are already dying or stressed... most notably, water stressed... in your case, the sprinklers spraying on it all the time was probably the culprit.

 

[Okie Chick]

Not the diagnoses I was hoping, but thank you for your time!

 

[Del_]

What kind of lawn fertilizer?

 

[Okie Chick]

I'm not sure... probably 10/20/10?
But that was last year. We've not applied anymore since then.

 

[Del_]

Some fertilizers contain broad leaf weed killers.

Broad leaf weed killers could stress your blackjack oaks and leave them vulnerable to hypoxylon.

 

[Okie Chick]

Thank you Del. I'll take note of that!