I dont know where the "trees" are originating from, but, I do know one thing...
When you get a "tree" from lowes or any other place, to wrap the tree top, in a burlap or plastic to protect them when you are transporting them from the store to home... I lost several trees that way, as they died when planted.
I commented to the Greenery I buy my trees from and they told me that they had a lot of complaints from others about this and started to wrap thier leaves in plastic and burlap, to protect them from the wind, while driving, (as a lot of people leave them hang out of trunks when driving down the road).
Now, dont know if this will help others, but, any trees I buy now, I make sure I do this as a protection...
Just my two cents for what its worth, and a wee bit extra for the collection plate...
Jesse