I have been answering gardeners’ tree questions for 54 years. I thought you might like to see some of the more interesting ones.
Why is the bark falling off my myrtles?
That is normal. Horticulturists call it “exfoliating” bark. Sounds dermatological. The reason this happens is because bark is a dead tissue that cannot expand as a tree’s trunk grows. All it can do is pop out in pieces and fall to the ground. Crape myrtles, sycamores, paper birches and a few other species happen to do well in large sheets of paper-thin bark. Other trees shed much smaller pieces. Anyway, it is a normal phenomenon and not a cause for concern. New bark is being formed just inside.
Why is the bark falling in large sheets from my live oak trees?
At first glance you might think this is a variation on the exact same question, but it is very different. This is the result of injury due to extreme cold. Arborists call it ‘radial shaking’ and it refers to the bark loosening from the phloem and other internal layers. We saw it after the terrible cold snap of February 2021, and we Texans actually lost 10 to 15 percent of our live oak trees. Many of the trees lost only some of their bark, and those trees are struggling to recover. All we can do is wait and watch, although you may want to hire a certified arborist to ensure the tree doesn’t fall unexpectedly.
Why is the bark on the trunk of my red oak splitting?
That’s almost always due to sunburn, and it’s almost always on the west or southwest side of the trunk. That’s where the summer sun hits the tree when it is first planted. The tree was in the shade of other trees in the nursery, but suddenly it is outside in full sun. The damage manifests itself after two or three years, and by then it is too late. If you have a newly planted red oak, red maple (Acer rubrum) or Chinese pistachio, immediately apply paper tree wrap from the ground to the lower limb to protect it. Leave it for one to two years.
Will English ivy growing up the trunk of a tree damage the tree?
Probably not. The vine uses only the trunk of the tree for support. The roots cling to the bark but do not penetrate the wood to draw water or nutrients from the trunk. The only way the ivy will cause problems is if it grows on the branches and shades the canopy, or if it adds enough growth to the branches so that its evergreen leaves can add weight during an ice storm. You are always safe if you only prune it to a manageable height on the trunk itself.
Do roots appearing on the surface of the soil under my tree indicate erosion? In other words, should I add soil to cover them?
No to both. The old axiom is that 90% of a tree’s roots are in the top foot of the soil. To some extent they reflect the growth of the limbs. The branches of most trees are relatively horizontal; live oaks are a classic example of this. As the live oak grows, so do its branches. And as the branches grow, so do the roots. Those that were originally only 3 to 4 inches below the soil surface will grow larger until they grow up and emerge from the ground.
There are mature live oaks in southeastern Texas and along the Gulf Coast with enormous buttress roots 2 to 3 feet in diameter. No erosion has occurred, so there is absolutely no reason to add soil. That would even be very harmful to those trees.
Leave surface roots alone. If one or two threaten your foundation or sidewalk, cut and remove them in the fall, but do so while they are still small (less than 2 or 3 inches in diameter for a 15 or 20 inch tree).
What causes rows of holes in the trunk of my tree?
Gaps in rows are caused by woodpeckers and sapsuckers. Unless they repeatedly hammer the same tree at the same level, they will not cause lasting damage to the tree. More serious damage happens occasionally to holly and other smaller trees, but rarely to others.
Still, you will see the effects of their work on pecans, oaks and other shade trees. Don’t worry about it. They generally bore their holes and later return to feed on the sap that flows from the small wounds. If you think this is necessary, you can apply a pruning sealant over the holes. Otherwise just keep an eye on things. The bird will eventually move on to other targets.
Are root feeding rods a good way to water and feed my trees?
They are fine as long as you don’t push them more than a few inches into the ground. Remember what we discussed earlier: 90% of a tree’s roots are in the top foot of the soil. Those rods will tempt you to insert them too far. You will miss most of the roots.
Likewise, drilling holes in the ground and filling them with fertilizer puts far too much plant food in a concentrated area and none within just a few inches. It is much better to apply the surface, followed by plenty of watering.
Are the water bags around the tree trunks a good idea?
For small, first-year trees perhaps, but not after that in my eyes. The roots of a tree extend to the branches (the “drip line”). That’s why you’ll see the recommendation to water around the perimeter where the feeder’s root growth is most active. Soaking the trunk does almost no good. And how many people are willing to fill those bags every day? That is the amount of water required to meet the needs of growing trees. No. No thanks. Give me a drip tube that I can twist around that IV line.
