I must comment on an article I recently read in a free gardening newsletter found in a diner. I hope this is not where most gardeners find their information. In the newsletter there was a question and answer column with highly suspect advice. The questioner wrote in asking if English Ivy
was hurting his maple tree as it was climbing up the trunk. I think the question was, maybe, wondering if the vine was some kind of parasite.
I have observed ivy climbing many houses, trees, fences, etc. and I can fairly well state that unless the tree is really weak and would fall down from the weight of the vine, it is really fine. The vine is just using the tree, or whatever, as support and is in no way a parasite*. It also cannot possibly overwhelm a big tree like a maple or oak.
Let me quote the fine answer this columnist gave:
“The plant is an aggressive climbing vine.”…”As the ivy climbs in search of increased light, it consumes and kills branches by blocking light from the tree’s leaves.”
I have never seen this occur. I have, however, seen ivy with no damage to the branches/trees for over fifty years of growing up the trunks. The columnist does not mention one slight problem with vines growing up a tree trunk and that is gypsy moth.
In the “old days” when gypsy moth was in its glory days and just moving into the midwest, it munched on many species of trees in residential areas. After feeding, the females seek a secret area to lay eggs. Since the pregnant females can hardly walk, they are so full of eggs, they like to walk down the trunks of trees and lay eggs under the cover of vines which are growing up the trunk. I would often find eggmasses hidden amoungst English ivy leaves.
a real problem since gypsy moth has settled into a more moderate pest status with predators, parasites and diseases keeping it in check.
Back to this fine article:
“On the ground, English Ivy forms dense monocultures that exclude native plants, not just weeds. It also serves as a host for bacterial leaf scorch, a pathogen harmful to elms, oaks, maples, and other native plants.”
It does neither. I suppose this author has never supervised a landscape crew pulling weeds and “native” plants out of a bed of ivy. As for the unnamed bacterial leaf scorch, I know of no pathogen that attacks that wide of an array of plants and certainly not that array and ivy doesn’t get anything. Bizarre.
This goes on:
“Maple roots…With a mat of ivy on top are short-changed of water, and nutrients.”
Well, except for the fact that a maple tree has roots going all over in a very wide pattern and the ivy is usually in a small planting bed around the tree. I guess if the ivy was planted in a really huge bed, it would steal food from the tree about 5% but it doesn’t have the ability to block water that much. As for nutrients, that tree will get food just fine. The ivy is not that heavy a feeder.
I am weary of this odd question and answer. One of the things I have always disliked about gardening is there is a lot of wacky advice out there. I will put this article in my category of “wives’ tales.” Here is my advice to my loyal readers, do not get your gardening information from your local diner.
*Regarding parasitic vines, the reader may want to view a previous post on the true parasitic plant, Dodder.