i would remove anything contrary to mother nature ...

years ago.. i had a hosta supplier do such.. i left it.. many died.. i dont know if the goo was the cause ...

research and advice.. can make mother nature.. and the process predictable ...

as far as i am concerned.. this is adding a variable ... and too many unknown variables.. usually lead to a failure ...

that said.. if you are doing many.. experiment with leaving it.. on a few ... no one ever learned anything without an experiment .... but i would probably keep the media rather dry.. which is what you should do anyway.. for a tree .... [after good watering in on the transplant, of course]

all that said, again .... sounds like an interesting way to insure the roots dont dry out completely in shipping ...

ken

In the past I had had a nursery say to wash it off. It was a perennial plant though, but i would guess the info is the same.