On Thu, 16 Dec 2004 19:09:40 -0600, effi wrote:

oak tree limb about 8 inches in diameter has a section of swingset chain
inside it now, bark grew over chain and chain cannot be pulled loose now

will chain posion tree?

Posion the tree, no. Choke the life out of the limb, yes. What I've done
in the past is to take a 1/2 inch chisel and chisel through a link.
Swingset chain, dog chain, fencing or guy cables, I've cut them all this
way. After the link is broken, the tree will be able to expand as it
grows, instead of being choked to death. Don't worry about removing the
chain, the damage will be much worse.
If the chain is deeply embedded in to the branch, then I'd cut two links.
One on each side of the limb.
HtH