I'm shocked- shocked! - that a distinguished artist would borrow a tune for a sweet poem! It scans perfectly with the tune. I too have always loved Nonesuch, and from the same source Charley cited.
It wasn't Nonesuch but another Pete Seeger album, a live concert- I think with Brownie McGee- that he included in the intro to one song -'Tarrytown'?- that "Woody Guthrie used that melody for some of his best tunes."
I don't think the Tune Police will be showing up in Port Washigton any time soon.:)
Carter Bannerman