This winter, more than ever, I noticed a marked increase in the prevalence of ivy in our urban forest. Especially in many of the rental home areas. It's fair to say that the property owners may not visit the site regularly and the tenants probably don't care too much about the health of trees. 
There is also a high occurrence of homeowners who have ivy, mainly English ivy, which has enveloped the trunks and in many cases has been permitted to grow into the canopy of their trees.
Many of us are unaware of the added stress that this can cause to our trees. Here are some of the issues that ivy may cause:
- Competition - this is true for air, light, and nutrients from the soil
- Suppression - as ivy grows it attaches to the bark of the tree and reduces latent bud growth and twig elongation
- Structural stress - the added weight of the ivy can cause branches to break prematurely especially in windy, rainy, or icy weather conditions
- Root rot - ivy at the base of trees can cause the base of the tree to stay moist for extended amounts of time (acting almost like a mulch) and this can cause an environment for wood decay fungus. This is a common problem in irrigated areas. Trees do need ample water but there must be an exchange of oxygen in this area to promote healthy growth.
- Covering up problem areas - Ivy acts as a wallpaper for trees and reduces the visual signs of stresses and defects, as mentioned above root rot is an issue. Ivy also can hide holes in the trunks and main branches of the tree, weak branch attachment points and diseased limbs.
Irregular growth - the presence of ivy in the crown of a tree will reduce the number of buds and limbs that are initiated in the interior aspect of the tree. This causes the limbs to reach farther away from the center part of the tree and run to the sunlight. If we were to prune a tree leaving only foliage at the ends of branches it is called liontailing. This is not a proper pruning technique and ivy can cause a tree to grow in this fashion. This can cause potential for structural weakness. This will also lead to a reduction the the photosynthetic capacity of the tree as the root to crown ratio is reduced. In short the tree can not produce enough healthy green leaves to produce food stores for the trunk and root system and the tree is in a deficit state (consuming more energy than it can create). That can cause an overall health decline in the tree which may eventually lead to death.
What to do if you have ivy in your trees
If the ivy can be removed from ground level, it maybe a job that most homeowners can tackle themselves. If if requires working from a ladder, I recommend professional help. Ivy removal requires a lot of pulling and jerking which just isn't safe on a ladder. A certified arborist has the proper tools, knowledge, and techniques to safely and properly remove the unwanted growth and recognize any defects along the way.
If you decide to do the work yourself here are some things to keep in mind. Limit chainsaw use to a minimum. The use of a motorized saw can cause over cutting and unwanted damage to bark and cambium layer of your tree. 
Many trees such as Pine, some Oak species, Black Walnut, and Osage Orange have thick bark and can handle some damage. Other trees such as Sycamore, Cedar, and Cherry have thin bark and extreme care must be used to avoid cambial damage which can interrupt vascular tissue flow. Also keep in mind that younger trees have tender bark when compared to more mature trees. A fine tooth hand saw and or lopper type pruners and a pry bar are your best bet. Removing ivy is very similar removing wallpaper. Sometimes it comes off in long strips and sometimes very small pieces. Overall it can be a very time consuming and dirty process. Be aware that some people maybe sensitive to the oils in the ivy so it is important to wear gloves and cover exposed skin and wear a mask if you happen to be allergic. If you can't reach all the ivy you can cut a 6 foot swath from ground level up the trunk. Pull off all the vines and the ivy above the cut point will wither away and die. It may not look too good when all the ivy is brown and the tree is green but at least it will stop any further growth. After this point you must periodically cut away new growth at the trunk of the tree.
I don't get many calls specifically about ivy. Most of the time I am visiting customers and it is an issue that I bring to their attention. In one instance a customer was unaware of a completely dead tree. I pointed it out and they always thought it was alive due the how green it was. Well the green foliage happened to be poison oak.
Ivy and trees can live in harmony as long as the ivy doesn't choke out its host. If you need help with any of your tree care needs, please let us know. Please email joanna@woodlandtree.com or call us at (901) 309-6779.