A couple of years ago I posted here seeking advice on watering policy
for 6 paper birch trees that were planted to screen a large building
project.

All has gone well and the trees seem fine, there are nice new buds and
the trees are probably established enough to rely on the local
rainfall. After planting they were well supported by a criss-cross of
pegged steel cables and these have done their job well. However,
having just inspected the trees, it appears that 3 of them have
produced growth round the cables which are now trapped. Here's an
example..

http://dl.dropbox.com/u/10508583/cable%20trapped.jpg

Can anyone advise? I've been in touch with the planter but he's not
responding. Should one whittle away with a sharp saw/knife until one
can get enough purchase to wrench the cables out or sever the cables
so that a short length is left within the trunk of the growing tree?

The trunk is about 3" diameter btw.

Would appreciate any suggestions...