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AIR POTATO VINES, considered an invasive species, are native to Asia and the Philippines and are related to the sweet potato. Photo courtesy of the University of Florida Institute of Food and Agricultural Services
Often I am asked if vines growing on a tree will hurt the tree.
Generally, letting vines grow on trees is not a good idea. The main problem I have with vines on trees is the vine can hide any structural hazard such as a canker or decayed area that might exist in the tree trunk.
Left covered or unnoticed, a canker or decayed area is a weak spot that could cause the trunk or branch to break at that point causing personal injury or damage to property.
There are two types of climbing vines -- the vines that grow straight up the trunk and the vines that circle the trunk as they climb.
Circling vines such as wisteria can wrap so tightly around the trunk that the vine stems can strangle or girdle a tree over time as the trunk attempts to expand through normal growth. Vines that grow straight up the trunk will not girdle a tree.
Shading, a bigger problem than girdling, can occur with both types of climbing vines.
Shading occurs when the vine foliage overtakes the tree foliage and begins to shade and crowd out the tree foliage. Aggressive vines can cause tree decline and eventual death. Some of the more aggressive exotic vines are: confederate jasmine, yellow jessamine, English ivy, ficus and wisteria.
Some native aggressive vines are wild grape and Virginia creeper that can overwhelm a tree if left unchecked.
And finally some invasive or poisonous vines found growing on trees are: Air potato (Dioscorea bulbifera), earleaf greenbrier (Smilax auriculata) a native, and poison ivy, also a native. The latter three vines should be removed. Take precautions including protective clothing if you are trying to remove poison ivy.
Vines on an older tree are a source of competition for the tree roots. A young vigorous tree is better able to compete for moisture and nutrients with surrounding plants than a mature tree. Also, in my opinion a healthy tree looks good and doesn't need a bunch of vines for decoration.
But, some people like the look of vines on their trees and do not want to remove them. If that is the case, they can clip the vines at the base once or twice a year causing the upper portion of the vine to dieback. New vines will grow from the pruning cut for the next growing season. This way, the vines will not grow into the upper canopy and the vines will be more or less kept in check.
There are two ways to kill vines. The first, a non-chemical method, is to cut the vines off near the ground. When the vines sprout again, cut them again and again and again. It will take persistence on your part, but the vine without leaves will gradually run out of stored energy and die. Some vines like smilex have large tubers which store lots of energy and will continue to sprout for some time. If you decide to dig up the tuber, be very careful that you do not damage or cut large tree roots in the process.
The second removal method involves the use of glyphosate concentrate (Roundup or generic equivalent).
Obtain a concentrated form of the chemical which normally is diluted with water before use. But do not dilute the glyphosate with water. Cut the vine and immediately paint the vine stub end protruding from the ground with the concentrated glyphosate. The chemical is taken into the roots and will hasten the decline of the vine. You may have to repeat the process one or two more times on large, stubborn vines.
As always, follow the label instructions of the product. There is little research indicating that glyphosate can be translocated across root membranes from the vine roots to adjacent intertwined tree roots.
But, some anecdotal evidence exists. If you are concerned about damaging a tree because of the size and number of vines to be cut and treated with glyphosate, use the non-chemical cutting method to get rid of the vine.
Chuck Lippi, certified arborist #$5051A, is a consulting arborist and can be reached at (904) 794-4200 or http://shadeTreeExpert.com