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Trunk and Structure on New Trees
Last month I wrote about the all too common issue of kinked or girdling roots in trees. I promised then I would cover trunk issues in new trees this month. So let?s dive right in.
Ideally, when inspecting a newly arrived or planted tree, what you want to see is a strong, well tapered trunk with un-topped branches well-spaced from top to almost bottom, and radiating out in all directions. Unfortunately, what you often find is a skinny, no-tapered, naked, topped trunk, supporting a congested cluster of once or twice topped branches.
In fact, it?s so bad out there, I often reject shipped trees, or refuse to purchase those I see. I recently set out to purchase three 24 inch Chinese Pistache at a local nursery. I ended up going to three different nurseries, but still came back 2 hours later, empty handed and discouraged. Fortunately, I kept my resolve not to give in and support such lousy tree ?care? with my money?for I really did want to purchase those trees, and right away.
Let?s take a closer look at each of the issues I mentioned earlier, item-by-item, starting with the attachments and locations of the branches, in relation to the trunk. In arboriculture, the term lifting is used to describe the act of pruning off branches on the bottom portions of a trunk, thereby creating the effect of the foliage having been ?raised?. A good and simple rule of arboriculture is that you want to ?lift? your trees no more than 1/3 of the distance up the trunk. The same holds true for the trees at nurseries, or newly installed in the landscape. I?m actually a little more comfortable with striving to not have trees lifted more than ¼ of the way.
The reason this is important is that those lower branches on the trunk serve two basic purposes of great benefit to the tree?they strengthen and shade the trunk. In terms of strengthening the trunk, branches have their greatest effect right at and around their point of attachment, and a little bit below. To have a trunk be well cloaked all along its length is a very good thing, for that trunk is likely very strong, and visibly thicker than a trunk that?s been largely stripped of foliage.
The shading of the trunk can be just as critical, especially in some of the inhospitable environments we ask these trees to grow in. Thick, sun-resistant bark is built up slowly, over time. Furthermore, trees develop their bark to meet the conditions they?re grown in. If a tree has been grown in a nursery, perhaps under shade cloth, surrounded on all sides by others of it?s kind that also provide shade to one another, it develops it?s bark to meet the challenges it faces. If you take that tree from it?s protected environment, and slap it into direct and full sun, you?re almost begging that a substantial portion of the trunk to burn, and die. Few injuries are as devastating to the health of a tree than a sun burned trunk.
I should take this opportunity to point out that other protective measures can be used to protect the trunk from sunburn. A tree can be installed in a location that offers shade to the trunk, either from other trees, or from a nearby building. Also, further protection can be achieved through the use of white latex (water-based) paint on the trunk, which reflects much of the light and heat. Temporary trunk wraps, whether in the form of a purchased product, or a piece of burlap firmly but loosely held in place, offer the same protection. Out of those two options, I prefer the wrap to the paint, for I just don?t care much for the look of white washed trunks, and when the need for extra protection is gone, the wrap can be easily removed, while the paint cannot. But, why undergo the additional expense and labor of installing a trunk wrap, when the same foliage that is strengthening the trunk, can also shade it.
Another common problem of newly purchased or planted trees is that they are often topped, to force a dense flush of branches and foliage at the top. In fact, those branches that grow as a result of this topping cut are often themselves topped again, to help further create a dense canopy of foliage. This practice is so very detrimental to the development of good long-term structure in the tree. You see, branches should be well spaced along the length of a trunk, and when you?re talking about permanent scaffold branches on a tree that will grow quite large, those branches should be spaced 18 to 24 inches or more apart. The effect of topping the trunk creates a situation in which those branches all originate mere inches from one another, and the majority of them should be removed, in time, leaving just one or two behind.
The other effect of topping a saplings trunk, is that the trunk itself is lost, and often none of the new branches are well situated to take over that roll. Many times, all of the branches that arise as a result of the topping wound, are attached at crazy angles, and often interfere with one another, so that they themselves do not develop a lot of secondary laterals because of all the shade created in an overly dense canopy. The challenges created by this practice are often very difficult to overcome, and sometimes impossible.
Furthermore, topping itself creates injury that is difficult for the tree to seal, and can create extensive tissue dieback well down into the branch or trunk affected. Topping is improper pruning, and it is disappointing to see it so often practiced by nurseries.
One final thought on this subject that I want to clarify is what I mean by good trunk taper. Good trunk taper is when the bottom portions of a trunk are substantially thicker than that above. In other words, the trunk gradually goes from thick and substantial at the base, to the thin wood that naturally occurs up near the top. Good trunk taper is a sign of a healthier tree, even if it has been subject to the removal of substantial portions of its lower branches. Such a trunk is much more likely to be able to support itself without staking, either right away, or much sooner than its skinny-trunked counterparts.
There are many more issues to consider when purchasing, planting, and maintaining young trees. Look for future articles to cover some of those issues, for the care and maintenance of young trees is so very important to developing older, healthy and valuable tree specimens. And remember, don?t hesitate to send back, reject, or not purchase trees that have been grown with substandard cultural practices.
Ideally, when inspecting a newly arrived or planted tree, what you want to see is a strong, well tapered trunk with un-topped branches well-spaced from top to almost bottom, and radiating out in all directions. Unfortunately, what you often find is a skinny, no-tapered, naked, topped trunk, supporting a congested cluster of once or twice topped branches.
In fact, it?s so bad out there, I often reject shipped trees, or refuse to purchase those I see. I recently set out to purchase three 24 inch Chinese Pistache at a local nursery. I ended up going to three different nurseries, but still came back 2 hours later, empty handed and discouraged. Fortunately, I kept my resolve not to give in and support such lousy tree ?care? with my money?for I really did want to purchase those trees, and right away.
Let?s take a closer look at each of the issues I mentioned earlier, item-by-item, starting with the attachments and locations of the branches, in relation to the trunk. In arboriculture, the term lifting is used to describe the act of pruning off branches on the bottom portions of a trunk, thereby creating the effect of the foliage having been ?raised?. A good and simple rule of arboriculture is that you want to ?lift? your trees no more than 1/3 of the distance up the trunk. The same holds true for the trees at nurseries, or newly installed in the landscape. I?m actually a little more comfortable with striving to not have trees lifted more than ¼ of the way.
The reason this is important is that those lower branches on the trunk serve two basic purposes of great benefit to the tree?they strengthen and shade the trunk. In terms of strengthening the trunk, branches have their greatest effect right at and around their point of attachment, and a little bit below. To have a trunk be well cloaked all along its length is a very good thing, for that trunk is likely very strong, and visibly thicker than a trunk that?s been largely stripped of foliage.
The shading of the trunk can be just as critical, especially in some of the inhospitable environments we ask these trees to grow in. Thick, sun-resistant bark is built up slowly, over time. Furthermore, trees develop their bark to meet the conditions they?re grown in. If a tree has been grown in a nursery, perhaps under shade cloth, surrounded on all sides by others of it?s kind that also provide shade to one another, it develops it?s bark to meet the challenges it faces. If you take that tree from it?s protected environment, and slap it into direct and full sun, you?re almost begging that a substantial portion of the trunk to burn, and die. Few injuries are as devastating to the health of a tree than a sun burned trunk.
I should take this opportunity to point out that other protective measures can be used to protect the trunk from sunburn. A tree can be installed in a location that offers shade to the trunk, either from other trees, or from a nearby building. Also, further protection can be achieved through the use of white latex (water-based) paint on the trunk, which reflects much of the light and heat. Temporary trunk wraps, whether in the form of a purchased product, or a piece of burlap firmly but loosely held in place, offer the same protection. Out of those two options, I prefer the wrap to the paint, for I just don?t care much for the look of white washed trunks, and when the need for extra protection is gone, the wrap can be easily removed, while the paint cannot. But, why undergo the additional expense and labor of installing a trunk wrap, when the same foliage that is strengthening the trunk, can also shade it.
Another common problem of newly purchased or planted trees is that they are often topped, to force a dense flush of branches and foliage at the top. In fact, those branches that grow as a result of this topping cut are often themselves topped again, to help further create a dense canopy of foliage. This practice is so very detrimental to the development of good long-term structure in the tree. You see, branches should be well spaced along the length of a trunk, and when you?re talking about permanent scaffold branches on a tree that will grow quite large, those branches should be spaced 18 to 24 inches or more apart. The effect of topping the trunk creates a situation in which those branches all originate mere inches from one another, and the majority of them should be removed, in time, leaving just one or two behind.
The other effect of topping a saplings trunk, is that the trunk itself is lost, and often none of the new branches are well situated to take over that roll. Many times, all of the branches that arise as a result of the topping wound, are attached at crazy angles, and often interfere with one another, so that they themselves do not develop a lot of secondary laterals because of all the shade created in an overly dense canopy. The challenges created by this practice are often very difficult to overcome, and sometimes impossible.
Furthermore, topping itself creates injury that is difficult for the tree to seal, and can create extensive tissue dieback well down into the branch or trunk affected. Topping is improper pruning, and it is disappointing to see it so often practiced by nurseries.
One final thought on this subject that I want to clarify is what I mean by good trunk taper. Good trunk taper is when the bottom portions of a trunk are substantially thicker than that above. In other words, the trunk gradually goes from thick and substantial at the base, to the thin wood that naturally occurs up near the top. Good trunk taper is a sign of a healthier tree, even if it has been subject to the removal of substantial portions of its lower branches. Such a trunk is much more likely to be able to support itself without staking, either right away, or much sooner than its skinny-trunked counterparts.
There are many more issues to consider when purchasing, planting, and maintaining young trees. Look for future articles to cover some of those issues, for the care and maintenance of young trees is so very important to developing older, healthy and valuable tree specimens. And remember, don?t hesitate to send back, reject, or not purchase trees that have been grown with substandard cultural practices.
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