We are gradually clearing an old agricultural field that was once abandoned and we want to clear it again. We are using this field for multiple purposes, planting food plots, a vegetable garden, an orchard and nut trees. In order to get more sunlight into our field we keep culling trees on the edges of the field. We have been using girdling to do this.
A few years ago we started culling unwanted trees by girdling them. Girdling is the process of cutting the cambium layer or outer bark, down to the wood. In our method we use a chainsaw and make a shallow cut around the circumference of the tree in 2 places, usually about 4 inches apart; one upper; one lower, about one to two feet above the ground. It is important that the cut is made all the way to the wood specially in uneven areas of the bark. We usually do not cut more than 1/2 inch into the wood, because we want the tree to maintain its strength and remain upright until it is dead. We do not want to weaken the tree so that wind will blow it over easily.
Girdling Trees to Clear Land
Why does this work to kill the tree and how long does it take the tree to die? Trees have two types of vascular tissue. The Xylem (wood) which carries water and nutrients up the tree and the Phloem (inner bark) which carries sugars (sucrose) down the tree to the roots. The stored energy in the roots in deciduous trees is essential to new leaf generation each spring. When this source of energy to the roots is cut off, the tree will die. Sometimes death will take several years, but usually by the third year the tree is dead. This method can also be used to thin trees in a forest. In a forestry situation, you can come back and cut the tree down or just let it die and let nature fell the tree as it decays.
One of the benefits of girdling trees is that the wood can be used for firewood and it is kept dry naturally while the tree is still standing. If cut within the second to fifth years, when the tree is dead or near dead, the wood is dry but has not yet had time to begin to decompose. This drying while standing minimizes the time that firewood needs to “season” prior to being burned.
Using a Girdled Tree for Firewood
Why not just cut the tree down in the first place? The best time to cut an remove a deciduous tree is when the leaves are off the tree. We are not always available to cut the trees at this time of year, or we do not have enough time to cut down as many trees as we would like. By girdling the trees, we immediately stop further growth of the tree above ground and at the roots. The leaves will start to fall off after girdling, and will start letting in more light. You can girdle a tree in under 10 minutes. This allows us to stop the growth of a quantity of trees and still have the flexibility to remove them at our convenience. Since we are clearing a field, we do not want the cut trees creating clutter in our field and limiting our ability to mow or till.
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Tags: clearing, firewood, food plot, girdling, trees
Suggestion to save the ring barked/girdled Titirangi kauri tree
How to implement the method in practice
The vertical strip can be cut in several segments, going upwards from the ring bark groove. The depth of the vertical strip will be the same as the depth of the groove — which is 2 cm, according to the article linked above.
Maybe an implement already exists to split the sapwood away from the trunk interior, but I have no knowledge of such. Therefore, if I was doing it then I would machine such an implement from a rectangular slab of steel or aluminium by sharpening one end to a blade, like on a chisel.
The splitting would then be accomplished by sliding the sharp end under the sapwood then banging the blunt end of the tool with a rubber mallet to force it upwards. This would be done after first cutting out the perimeter of the graft strip, for example with a sharp stanley knife, to the 2 cm depth of the sapwood and with width equal to the tool width. The bottom of the strip would be at the height of the groove and the splitting would begin from the top of the groove.
The width of the metal slab should be about 10–15 cm to give an appropriate width for the graft strip. The slab could be as much as 1 metre long so the draft strip can be removed in as few long sections as possible. The slab should be thick enough to provide reasonable stiffness for the implement.
Once the vertical strip has been removed in sections, each of the sections would be cut into rectangular pieces of length precisely equal to the width of the groove where the piece is to be inserted.
The method relies on a tight fit of the pieces into the groove in order for the sap to flow freely, so there should be no gap at all at either of the top and bottom joins. Therefore, the groove should be cleaned up — cut square at both the top and bottom — and the length of the pieces should be measured in place to exactly match the span of the groove. The depth profile along each piece should also be trimmed to match that of the groove.
One by one, the graft pieces should be pressed into the groove, side by side going around the circumference, perhaps using a rubber mallet and then nailing the lengths down once they are in position.
When that is done, the tree should look like the middle graphic:
Hopefully the sap would flow again immediately, and then the bark would eventually heal up around all the joins — the graphic on the right. The tree would live!
Bridge grafting as a life-saving procedure for trees
In the previous article referring to trees damaged by rodents, I talked about doing damage assessment and collecting the scionwood. The objective of this article is to address the next steps.
Saving the trees
Before anything else, make an assessment whether or not the trees are salvageable; is it going to be worth the time and the effort of trying to save them? This is greatly determined by the:
- Extent of damage
- Tree age
- Tree spacing.
For the young trees (1-2 year old) with severe damage (100 percent girdled trunk), cutting the trunk back below the injured area will save the tree. This will induce the regrowth and the newly developing shoot should be trained as a replacement tree.
The older trees need more involved “surgical” procedure known as – bridge grafting. As hopeful and good as this procedure is, it is not the answer for all trees. Stone fruits (cherry, peach, plum etc.) are very seldom successfully grafted. The other undesirable effect is in creating the opportunity for many disease (i.e. bacterial canker) and insect invasion (borer complex). Pome fruits (apples and pears) are in much better position. Both, young and old trees are easily grafted without too much trouble. For older trees, bridge grafting is an easy operation with high success rate.
To proceed with bridge grafting, following steps need to be done first:
- Collect the scionwood (in anticipation of the damage)
- Inspect the damage
- Prepare the area around the tree to be grafted
- Perform the grafting.
The first two steps should have been done along with the winter pruning or as soon as possible in early spring. It is essential to collect the scionwood from the dormant trees.
The last two steps are performed in May when the bark is “slippery” and is easily separated from the cambium without any damage to the bark or cambium. If the injury is right at the soil line or slightly below, one should dig down to the healthy part. It should be left exposed to the sun so it can worm-up and become “slippery”. This is done at least 10 days prior to grafting to insure high and good take/healing.
It is important not to rush the procedure. If the tree is not sufficiently “awake” the graft will not take. Tree sap or “juice” must be flowing for bark to “slip” easy!
What makes a good scionwood?
- One year old growth at 3/8” in diameter. Water sprouts work well.
- Straight branches 15-18” long.
- Wood from healthy trees.
- Wood from disease (fire blight) tolerant trees.
- Cultivars for apples: Red delicious, Empire, Spy …
- Cultivars for pears: Old Home, Seckel, Kieffer …
Bridge grafting – step by step
- Clean up the wound and trim the bark to an even cut.
- Prepare a scion-wood by cutting it at 3” longer than the length of the wound .
- Make a wedge cut on both ends of the scion-wood.
- Make an inlay cut into the bark from the edges of the wound, approximately 2” long and as wide as the scion-wood.
- Remove the bark, so the healthy wood is exposed.
- Place the wedged scion-wood into the slit and affix it with the nails.
- Do the same with the other end.
- Make sure that the scion-wood is at the slight bow. That will insure flexibility and better cambial contact.
- Scion-wood should be placed every 3-4” apart all around.
- Upon completion, cover graft unions with the grafting compound or wax to preserve moisture and prevent drying out.
Completely girdled tree saved by the bridge grafts. Photo credit: M. Danilovich
Bridge graft is the best, if the ringbarked is complete it is the only way it will survive above the graft. If it is not complete what your doing should be adequate just make sure the remaining bark join stays alive.
To bridge graft, one grafts heathy sticks or bark from the same tree, from one side of the wound to the other, this reestablishes flow of sugars from the leaves of the tree to the roots http://www.extension.umn.edu/distribution/horticulture/components/DG0532c.html#bridge. I have never done it mysealf but it shouldnt be to hard as the tree would give it lots of sap flow. Maby wrap wound and grafts in plastic for first couple of weeks after operation to reduce dehydration of new wood. One of the most important things i have found when doing rind grafts which this essentialy is, is to wrap firmly to give good contact and seal well with wound sealent when finished, I use the italian wound dressing, the one with the pink lid not the tar one. liquid nails is also good but not silicon.
If you get stuck talk to your local nursuries if you are very lucky you will find someone with horticultral training who works there.
No fear you cant make it any worse. Good luck.
|Pictures – Click to enlarge|
Department of Transportation
Don’t do this to your tree; from blog.caseytrees.org
It’s time to go out and mow the lawn. Almost done, there are just a few tufts of taller grass right up against a tree trunk. It only takes a second with a weed whacker (or string trimmer) to remove the offending grass, but the tree might never recover. Hitting a tree with a weed whacker results in an ugly gash and can lead to disease and eventual death of the tree. The tree’s circulatory system is just under the bark; injuries to the area interfere with water, nutrient and starch transport between the roots and leaves. As a result, the tree may decline, leaving it more susceptible to pests and diseases. The injury opens the door to fungus, which can cause wood decay and tree death. If the wound completely encircles the trunk, death is inevitable.
Arborists call this damage “weed whacker blight,” and a recent survey of an SDOT corridor of young trees found that close to 60% of trees were victims. So what can you do to protect your trees (besides going easy on the weed whacker or lawn mower)? Simply prevent turf grass from growing at the base of the tree. Gently remove turf and create a ring of mulch 2-3” thick around the tree roots. Don’t pile up mulch around the base of the tree, which encourages decay. Instead of lawn, you can plant groundcovers or perennials which don’t need to be mowed near the base of the tree. If nothing else works, a flexible plastic sleeve around the base of the tree can prevent the worst of the damage.
Planting and mulching around base to prevent weed whacker blight
A plastic sleeve protects the trunk. From http://www.rainbowtreecare.com
Stem girdling root removal
Home > Root growth > Root collar exam and treatments > Roots girdling the trunk > Stem girdling root removal
Roots that girdle the stem (stem girdling roots) can be removed. There are many examples of this discussed below. If removal is easy and can be performed without damaging the trunk then go ahead and remove them. If removal is difficult consider simply cutting them without removing. One research report showed that removing all roots growing horizontally from two sides of the trunk caused no shoot die-back in the crown. Arborists who remove stem girdling roots as part of their regular tree care program report that roots can be removed until their total cross sectional area is 25 percent of the trunk cross sectional area at 4.5 feet from the ground. We used this 25% guideline to removed roots from ten 25-inch diameter live oak with no visible impact on the tree. The final cut when removing roots should be make tangent to trunk because new roots often grow back in the direction of the removed roots.
Roots grew up into the mulch that was maintained against the trunk of this declining tree for many years. There are too many roots growing over the root flare to treat.
Removing a girdling root growing over a main root using a hand saw.
After removal, the main root below is uncovered and can grow normally.
Lower trunks sometimes crack when a large stem girdling root is present. Cut this cedar root now and remove as much as possible.
Trunk crack on red maple from a stem girdling root. It may not be reasonable to think we can improve health on this tree.
Removing a larger girdling root can sometimes be accomplished with a chain saw. The two maple stem girdling roots in this photo were not grafted to the trunk.
Cut and remove these roots growing on top of the main flare roots.
This mess of small diameter maple roots growing over the main roots is very difficult to remove on certain trees.
This 4 inch diameter tulip-poplar root is easily removed; removal will improve tree health.
Girdling roots formed early on this elm resulting in a swollen trunk above the roots (see left side of trunk).
Trunk was swollen abnormally near the base of one side of this declining zelkova. This results from the phloem accumulating sugars from above that are unable to pass to the root system. Mulch and soil were removed with high speed air. Many large roots were growing around and girdling the trunk. See photo below for treatment.
Chisels and power saws were used to cut roots that were embedded into the trunk. Roots must be cut all the way through so trunk can expand. Chisel is a great tool for cutting roots that are embedded deeply into the trunk as shown above.
Girdling roots are when a tree’s roots wrap around themselves and cut off the water and nutrients a tree gets. Root girdling is common, and can kill your tree. Although it is common, it is not natural, as girdling is caused by environmental issues in urban settings.
The most common cause of root girdling is improper planting or transplanting of the tree. Trees that spend too much time in pots can get girdling roots. The roots keep growing but have nowhere else to grow, so they wrap around themselves. This can also happen when a tree is planted in a hole that’s too small.
It’s important to keep this in mind when planting a tree too close to foundation or a sidewalk, as this can also impede the roots from growing naturally. Leaving pieces of the container in which the tree was grown in can also affect the growth of the roots later on down the line.
You can tell if your tree has girdled roots by checking the trunk for an abnormal flare. Normal trees have trunks that flare from the ground, but trunks with girdled roots have skinny trunks. The leaves will also show signs of distress, such as early leaf drop and canopy dieback.
Prevent a tree from getting girdling roots by digging a large enough hole for the roots to grow. The hole should be about three times as large as the root ball. Do not put mulch right up against the trunk. If the root ball is encircled around itself, make sure to break the root ball up before planting it.
If you think your tree may be suffering from girdled roots, contact a professional arborist.