Drought Damage

[LeeB]

Several of my oaks and many more of them in the surrounding area have had their leaves turn brown in the last few weeks. The change has been just about overnight, or at least it seems that way. We have been suffering the high temps and lack of rain like so many others. My question is; Are these trees dead or will the possibly leaf back out next year? If there's hope I won't harvest them.

[WDH]

If the bark has gray patches on them, they are toast.  Hopefully, they don't. 

[LeeB]

Are the gray patches fungal or dead bark?

[customsawyer]

This isn't going to help you much but I have seen them go both directions. Some times they will leaf out again the next year and some will be dead. Unless you need the wood for something I would give them a chance to come back around.

[WDH]

A sign of hypoxylon canker.  

https://cdn-ext.agnet.tamu.edu/wp-content/uploads/2018/10/EPLP-030-hypoxylon-canker-of-oaks.pdf

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/cankers/hypoxylon-dieback-of-oaks.aspx

[LeeB]

I'll check the trees more closely but I don't believe this is the problem.

[beenthere]

Oak wilt disease would be my guess, as the symptoms are something I am used to seeing. 

Erratic weather, multiple pathogens may lurk behind ?overnight flagging of oaks?

[LeeB]

I don't believe it's oak wilt. I saw plenty of that before we left Central Texas. There was no initial yellowing of the leaves and the green veins. The branches don't have the dull grey dead coloring of oak wilt. The leaves have gone straight to brown like they had been frost killed. I looked at a tree on the side of the road this morning on my to town and saw no signs of hypoxylon but I didn't study it real close. I will check the trees on my place when it cools off later this evening. 

[beenthere]

The leaves have gone straight to brown like they had been frost killed.

That is exactly how my oak trees have died the last several years. I will lose one or two in the yard nearly every year. They look fine until mid summer. Suddenly there are many leaves that turn brown and then fall (like it is the fall season, but early). Not a pretty sight, but very little that can be done to save them. Oak wilt has been around for the last 60+ years that I know about in this area of Wisconsin. 
I also am familiar with the yellowing of leaves on trees when they are stressed. That situation hasn't proved to be a death sentence from what I've seen. More related to soil conditions (drought?) and stress.

Hope yours is not the oak wilt. 

[LeeB]

I guess it could be oak wilt but it just doesn't look the same as the oak wilt I have witnessed in Texas. The infestation there was quite heavy and moves slowly from tree to tree, rarely jumply large distances. This all appeared here at one time over a several county area. Oak wilt has been here in the past long before I moved here but has been pretty much inactive for a long time. I would hate for it to be back again. A large part of the trees in the area are oaks. I suppose if it did happen it would put the land back to where it was a century or two ago.

[LeeB]

I wish this one time Danny wasn't right but it looks hyphylon is the culprit. I couldn't see the signs of it on the bigger trees but quite a few of the smaller ones are definitely infected.  

[customsawyer]

That drought y'all are in is pretty bad. I came across on I40 last month and there were lots of small fires from cigarettes getting thrown out the window. With that big of a area getting effected and the oak lumber market on the down swing, it could hurt some folks.