Ivy can destroy trees
Ivy is a great ground cover and does help keep hillsides from eroding. However, when left uncontrolled it can climb up and damage trees. Small trees to very large Fir trees can be killed by Ivy choking them out. A good way to control this is to keep it a couple feet away from the trunk. If you already have Ivy climbing up your tree, removal is your best bet. If not possible to remove it all, it is good to at least cut it off the bottom portion that you can reach. This will kill the Ivy to prevent damage.