1) add planks around a tube core , then round over (as was allready
sugested) and make them look aged - use a belt sander with a coarse
belt to get the "surface finish", then paint them to match the looks of
an old pole.
2) to keep the exact appearance: make a silicone mold from an old
telegraph pole, split it in two halves, use fiberglass & resin to
obtain a shell that can be glued around the tube, paint in order to
obtain the old look (this is rather a joke, as it would prove to be
quite expensive, however this is how tree trunks are made for studio &
stage forest scenes)