"symplastless" wrote in message
. ..
I try to make decisions based on data. I don't like ivy in trees because
it
covers signs of high risks of hazard such as cracks. I don't like ivy on
trees. But I have not read data that stated ivy kills trees.

How about the National Park Service?
http://www.nps.gov/
http://www.nps.gov/plants/alien/fact/hehe1.htm
ECOLOGICAL THREAT
"As the ivy climbs in search of increased light, it engulfs and kills
branches by blocking light from reaching the host tree’s leaves. Branch
dieback proceeds from the lower to upper branches, often leaving the tree
with just a small green “broccoli head.” ***The host tree eventually
succumbs entirely from this insidious and steady weakening. ***
In addition, the added weight of the vines makes infested trees much
more susceptible to blow-over during high rain and wind events and heavy
snowfalls. Trees heavily draped with ivy can be hazardous if near roads,
walkways, homes and other peopled areas. On the ground, English ivy forms
dense and extensive monocultures that exclude native plants. English ivy
also serves as a reservoir for Bacterial Leaf Scorch (Xylella fastidiosa),
***a plant pathogen that is harmful to elms, oaks, maples and other native
plants.****

Sincerely,
John A. Keslick, Jr.
Arborist

Loved your bear story, John. But, I gotta tell you, every arborist I've
known is just a little bit looney. I don't know if it's the chainsaw fumes,
or you just gotta be crazy to climb trees. (I climb in arenas to rig sound
and lights for entertainment events, and we may be a little bit weird
too...) No offense meant....