It's hard to tell from the photo if the white stuff is wet or dry. Have you tried to rinse it off? Does the tree otherwise appear to be healthy? If it's an isolated situation (only on the 1 leaf), I wouldn't worry about it, myself... I'd try to wash it off & if it doesn't come back, just chalk it up to something weird!

Assuming that this is a current photo, being that it's October & you are in West Virginia, I'm surprised that the leaves of a deciduous tree are so green! (Aren't your trees in 'autumn mode' there?) I notice evidence of a spider... could it be that this white stuff is a bazaar attempt at a cocoon?

I know NOTHING about trees... (nor about almost any plant life that isn't in a vegetable garden!) so I'm just punching around in the dark for guesses here! I'll watch for other posts & maybe learn something!
Good luck!

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