Good luck, you'll need it. It's a very short lived tree (as you state) not suited for the climate.

You'd probably have as much luck growing aspen or spruce. I'd replace with a river birch, which naturally occurs in the state and with water, will thrive.

We do have a river birch, don’t want to just kill this one, want to give it a fighting chance.

Any idea what the problem is? Can’t be heat it hasn’t been above 82 yet, they can see that temperature in their native zones

I agree with Bill - amending a planting hole in clay soil is a recipe for disaster! The enriched, amended soil absorbs and retains moisture and the surrounding clay prevents proper fast drainage. The result is root rot and there is no recovery from that.

If it does survive, it won't for long. BBB will get it sooner or later.......probably sooner.

My advice for your parents, and indeed for all human transplants is to try to embrace their new environment wholly and learn to love the kinds of plants suited for their new home. If I had a nickel (as the saying goes) for every customer who wanted to duplicate their northern garden after moving to the deep south.......

I agree with all the comments about it not being adapted to growing here.

Do you remember if it started budding out just before that big cold spell a couple of weeks ago? Perhaps the cold nipped it back, which is fairly common here where our temperatures can swing from the 20s or 30s to the 70s or 80s some springs.

Keep in mind that much of OK had record-setting rainfall in the fall and winter and for many of us, especially those of us with clay, the ground has stayed persistently wet since last September. It may be your clay bowl in the soil held too much moisture all winter long, the tree tried to recover and did indeed start to leaf out and then it failed. I'm a bit further south than you, also with dense red OK clay, and the only birch trees I've ever seen in my part of the state are dead ones---I've never ever seen even one live one except in containers in nurseries.

We have lived here in OK for over 20 years now and have found the pathway to happy garden plants is to plant natives and well-adapted but non-invasive non-natives. It is a losing battle to try to keep a plant alive when it is not adapted to our climate and soil.

Another thing to consider. Some areas of Oklahoma are high in soil salt and/or highly alkali. And this can vary spot to spot on any given area of land. So you want to choose trees that are tolerant to conditions in your particular planting area. A low spot might seem perfect for a tree like Birch but from what I understand, those are the spots that tend to be salty or alkali. Betula papyrifera hates soil salt so a soil test would certainly be in order when choosing a tree.

Update: we checked the soil moisture and dug it up, the soil was pretty good and non-saturated, added a little clay around the top to mound it, just slightly moist underneath. It did start to leaf out before the cold spell so maybe it is that. We have a river birch that’s doing great though it leafed out much later.

20's F would be enough to do that sort of damage. :?

Possibly if it goes from 70° to 28° in 2 days like it did at my place

That's would explain a lot. :^))

Normally, new shoots can take a bit of a nip early on but if it dips down into the 20's for several hours during the night time, that can be bad.

I've seen some years up here where the leaves are almost all the way extended and we get a cold spell that pretty much wipes them out.