Q: I live in Oracle and have a native oak with ivy growing up the trunk. I am wondering if it is a threat to the tree. I also have a mature netleaf hackberry covered by a native grape and another oak with a passion vine rapidly climbing to the top. Should I try to control any of these vigorous vines?
A:Β English ivy (Hedera helix) is in the ginseng family Araliaceae and it is the most troublesome ivy for trees and other landscape plants in a large part of the U.S. It is an aggressive plant that can rob trees and other plants of resources by climbing over them to seek sunlight and invading their root zones with their own to seek water.
However, it doesnβt typically do well in the desert. The trouble for English ivy here is the hot temperatures and dry, salty soil we typically have in southern Arizona. Your location in Oracle is probably just cool enough to allow it to survive in the shade with sufficient water. I doubt it would kill the tree but it could reduce its vigor. So with suitable habitat for English ivy and if it is doing very well, I would recommend cutting it back or down from the tree. Severing it at the base is probably all you need to do to keep it in check. Otherwise, you have a nice specimen of a vine that isnβt often seen here. The native Arizona grape vine (Vitis arizonica) is not typically a species we call a weed and worry about managing but if you find it growing so vigorously it covers a desirable tree or shrub, you could cut it back or out. Like many other vines, it seeks the high ground to get sunlight and can shade out other plants. Passion vine (Passiflora foetida) is often considered a desirable ornamental vine with beautiful flowers that is great for attracting butterflies so I wouldnβt worry about that one unless it compromises a tree you like better.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed toΒ plwarren@cals.arizona.edu.
