is that native yellow sand????

how are you insuring deep proper water in that slight hill????

is it moist.. thru the whole root mass planted???

where are you???

is it a deciduous tree ....??? ...

first link says: semi-deciduous tree can be drought deciduous in dry soils ...

and such would be substantially increased by transplant ...

dig a small hole with a hand trowel.. at least half as deep as that planted .... and find out moisture at depth ...

same with your other tree in the other post ...

all that said.. a little leaf fall ... in fall .. after transplant.. wouldnt surprise me ... we just have to make sure... it has proper water.. to get the roots settled in for next spring ... w/o rotting them off ...

ken

Here is a link that might be useful: link

Chances are that it's drying out.

When you water, make certain it goes into the stuff that was in the 36" box.
Determine if that original soil/rootball is dry or too wet by sticking a finger into it.

Don't rely on rainfall to irrigate sufficiently. Check the soil to determine if it's dry or too wet.

Also, remove that one stake as it was there to stabilize the tree in its pot.
If the tree needs to be staked, use a 2-stake system as shown at the link, below....

Here is a link that might be useful: plant & stake a new tree