Thanks to everyone for the helpful info on chlorine and tree roots. Now I'm trying to get a more complete understanding of ivy and trees. I'm aware of the above ground negatives of ivy in trees, sunlight competition, ice loading, windsail effect and lenticel blockage. I've been trying to find articles, studies, etc., on the underground interaction of ivy roots and tree roots. I'd appreciate any suggestions and info on this subject. Thanks for the help. Tom

Reply to post by Tom Watson, on February 08, 2000 at 20:58:24:

Regarding the underground interaction of ivy
roots and tree rootsI do not know of any.
However, it looks like a great way for someone
like you or me (non-scientists) to contribute
to the information, because all we need is a
20x magnifier and some small digging tools.