Kudzu climbs by wrapping around objects, not by attaching to them. If the diameter of a trunk exceeds about 8", then kudzu can climb it only by wrapping around other kinds of vines that grow up the tree, or by wrapping around other "holds". English ivy or poison ivy are examples of vines that climb up tree trunks of any size. However, this is not usually how kudzu invades a large tree. The above photograph shows the kudzu-free trunk of a tree that is nonetheless surrounded by kudzu, and has kudzu in its upper branches: The trunk is too large for kudzu to wrap around it.
Kudzu can invade a tree by crossing over from a neighboring tree, but it is more likely to invade a tree from low-hanging branches. Kudzu is capable of about 3' of unsupported vertical growth. So if a tree branch is within that distance to the ground, or within that distance of some raised platform (scaffolding) upon which kudzu grows (old plant growth, small bushes, ground debris), then kudzu can reach the branch and grow up into the tree. In this way it can form a dense umbrella of kudzu foliage over the tree that blocks sunlight to the tree, which can eventually kill it.
Therefore, the best way to stop the existing growth of kudzu in a tree is to create a gap of 4' or more between the lowest branches and the actively growing kudzu beneath it ("gapping"). The easiest way to do that is by using a hand tool (pruners, powered cutters) to cut down any hanging vines up as high as can be conveniently reached. If the cut vines do not fall over, then it is also necessary to cut them off at the ground to prevent new vines from climbing back up into the tree on the standing dead vines. It also helps to clear the ground around a tree of brush and debris, or flatten it by walking over it. Even if kudzu is allowed to grow around the base of the tree, the cleared ground makes it harder for kudzu to reach branches. In that case the kudzu makes a convenient ground cover, especially on undeveloped land, as long as it is otherwise under control.
The cut vines in the tree quickly die, and sunlight once again reaches a live tree and stimulates new growth during the growing season. Pulling down vines from trees immediately after cutting them during the growing season can damage the tree. It is better to wait a few weeks for the dead vines to dry up before pulling them down. Doing nothing is also an option: Eventually the decaying vines fall down under their own weight due to the effects of wind and rain. However, partially fallen vines can form a path for kudzu up into the tree. So it is necessary to patrol the area occasionally to remove such debris.
During gapping, cut down very low hanging branches so kudzu has nothing to "grab". This also makes it easier to walk around the trees, and gives trees a neater and cultivated appearance.
Once all trees in an area are gapped, then monitoring is necessary to make sure kudzu stays out of the trees. While the initial gapping might be a fair amount of work due to heavy vine growth over many years, any work necessary during patrolling is usually much easier.
Be aware that some dead trees only remain standing because of supporting vines and neighboring trees! Cutting away vines and other debris can cause dead trees to fall. Therefore, it is necessary to carefully examine trees before removing supporting vine networks to determine whether a tree is alive or dead, and if dead whether it could fall after it is freed of vines. Falling trees injure or kill people, and damage property, so work safely and responsibly. If you experience "close calls", then you are not working safely! Under conditions where debris can fall, it is prudent for workers at risk to wear hard hats as a standard practice "just in case".
Sometimes vines hang over a creek or other unnavigable area, which cannot normally be reached without wading into water or walking onto inhospitable ground. One method useful for gapping in such a situation is to use a pole tree pruner to cut down vines. This tool is also called a "long-reach pole saw and lopper".
For example, the Corona TP3714 ($48) is a telescoping fiberglass pole that is 7 1/2 feet closed, and 14 feet fully extended. Pulling a rope moves a blade through a hook containing the vine. A saw blade can be attached, but the saw is only useful if the object being cut does not move easily. A saw is not effective for cutting hanging vines from a distance.
With a 14 foot reach, it is easy to cut vines down over a creek or ravine. A fair amount of strength is necessary if the pole must be held close to horizontal for extended periods of time. That is necessary whenever standing on a bank above a creek or ravine, and reaching over them to cut vines. If possible, buy the lightest possible pole. One other difficulty is that a long pole is awkward in underbrush, and sometimes gets caught on vines or bushes.
A good technique is to sweep the hook end of the pole pruner across the vines and pull the pole to hook as many vines as possible. Pulling the rope therefore cuts many small vines at one time. The largest vines typically encountered in trees usually fit into the hook for cutting. The maximum size vine handled by most pruners is 1". In the case of stiff vines larger than 1" in diameter, a saw blade attachment might cut the vine with effort. If a larger cutting hook is available, it might be better for the job as long as the additional weight is not excessive for long work sessions.
The pole is also generally useful for hooking something out of reach, which can then be pulled to a hand. Some other hand tool (hand saw or hand pruner) is then used to cut it. However, a vine too large for the pole pruner is unlikely to be pulled in this way due to its stiffness and large mass.
Experience reveals that it averages about 40 minutes per tree to cut vines with a pole tree pruner if it has not been previously treated. This time includes clearing away brush and thorny vines from around the base of the tree.
Powered cutting tools with a long reach are available, but the Coalition has not tested them. Again, for reaching above and across an obstacle, weight is an important consideration. This is less important when gapping from underneath vines, where powered tools such as string trimmers are time savers.
Revised November 2007