Bad things we do to good trees: Examples abound in North Texas landscapes
Our shade trees are proud to have a chance to prove themselves in our landscapes. If we’re careful when we choose them, and attentive to their needs from that day on, they’ll be faithful servants for many decades. But sadly, the wheels come off too often. Our trees are victims of our own poor decisions. Let me help you avoid these problems on down the road. Here is my list.
We plant trees too deeply. There is no quicker way to ensure a slow death for a prized new tree. It usually happens because we dig the planting hole deeper than necessary.
The weight of the root ball compresses and compacts the soil. The tree ends up too far down in the ground. Roots are depleted of oxygen, especially during periods of heavy rains.
The solution is to plant at the same depth at which the tree was growing in the nursery. Use a tape measure to determine the distance from the ground to the top of the soil ball. Then, as you dig the hole, lay a hoe handle across the hole and measure until the hole is the desired depth. Dig no deeper.
We leave stubs as we prune. This is so sad to see because the outcome is so predictable. People remove twigs, limbs, and branches. In doing so, they leave several inches of the old branch in place along the main trunk. The same thing happens when a limb breaks off and falls to the ground and we do no follow-up pruning to clean up the wounds.
Those stubs do not heal properly. Decay sets in after a couple of years. The entire stub decays and then the deterioration moves down into the main trunk. Bark starts to fall off as decay progresses, and within years the tree can be lost.
The way to avoid this: make each cut virtually flush with the main limb or trunk. Leave no stubs. It’s wise to leave just a very small piece of the branch collar to speed the healing. That “collar” is where the limb swells out as it attaches to the trunk. The roll of new bark will grow across that branch collar.
Topping our trees. There was a time 50 years ago that Texas gardeners felt they had to top many of the trees that they grew. Mimosas, fruitless mulberries, and crape myrtles were the usual victims of this bizarre butchery. Little by little gardeners have given it up, except for crape myrtles. Some people still live in the dark ages where mythical reasons find them out whacking their plants. Topped crape myrtles are disfigured forever, and their bloom output is delayed and diminished. There is no excuse.
Girdling guy wires and surface roots. If you place any rigid material against a tree’s trunk, the tree will eventually grow to encircle it. It might be another tree’s branch, or it could be a fence rail nailed to the tree’s trunk. There’s a bicycle in Washington State that was hung on the side of a tree 75 years ago. The tree has completely engulfed the bike within its trunk.
But that story takes us off track. The real message here is to watch out for wires, cables, nylon cords, and other permanent binds that we have around our plants’ trunk and branches. As the plants grow and thicken, those wires, etc., won’t stretch. They’ll end up girdling the trunk, thereby cutting off the supplies of water and nutrients from the roots to the leaves and then, more importantly, manufactured sugars from the leaves back down to the roots. You’ll see a swollen trunk immediately above the constricting cable or twine. It’s usually difficult to cut the wire or pull it out without doing serious harm to the plant’s tissues, but we all try.
Sunscald of trunks that have thin bark. This is extremely common on Shumard red oaks, red maples, and Chinese pistachios, as well as a few other species. It happens when the young trees with their tender trunks are moved from the nursery into full sun in our landscapes. After a couple of years of exposure, the bark on their western sides cracks and peels away, and we wonder what might be causing the decay that has set it. And now we know it’s sun scald.
It’s imperative that thin-barked species be protected with paper tree wrap from the ground up to their lower limbs for the first couple of years. Just a few dollars’ worth of the wrap can save a valuable tree in your landscape.
Line trimmer damage. When you let a line trimmer (or a hoe or a mower wheel) gouge the bark off a tree’s trunk all the way around the circumference, you’re doing the same damage as the girdling wire. The supply of sugars down to the roots has been cut off. The roots will die, and the tree is very likely to die. Leave a few inches of bare ground out from the trunk so you won’t run that risk or put a temporary guard in place around the trunk as you’re trimming.
Mulch volcanoes. You’ve seen them, but you may not have known them by that name. They’re the mounds of mulch piled up around trees’ trunks. Maintenance people must have put them there to conceal the fact that they didn’t remove excess soil left over from planting of the tree. And then they had to put down a fresh batch every spring because the old mulch kept decaying. Irrigation water and rainfall are shed away from the tree’s roots, and rodents are given safe harbor so they can gnaw at the bark. It’s just a bad look all around.
