Dishing the dirt-But it looks so pretty?

Published 3:28 pm Wednesday, May 25, 2022

I have made several house calls over the last three weeks looking at tree issues. The trees in our landscapes are dear to us as we watch them grow and enjoy their shade and protection. As our landscapes grow or as we decide to improve our homes, we tend to disturb our trees in the process. I see this quite often and even participated myself as a first-time homeowner.

When I lived in Hyde County, I purchased my first home. It was a grand old Victorian with several pecan trees surrounding it. I thought, “Man, this place sure would look good with a pond.” So, I borrowed an excavator from work and dug a pond. I piled the soil sky high and then built up the surrounding landscape with it using a large bulldozer. Roughly five years later, all but one of my pecan trees had died. I had my pond but my 90-year pecans suffered a dismal suffocating death.

The field visits I went to over the last couple of weeks all had my mistake in common. There were different trees involved as well, maples, arborvitaes, and a small pecan orchard.

The first set of the visits were three different homes with red and/or sugar maples. One added soil to the top of the existing landscape and then surrounded it with a gorgeous retaining wall. The newly-built bed was mulched and had flowers growing in it but the tree was suffering.

The next was much the same story but the last one actually just had the tree planted too deeply which will result in the same death. You can always tell by where the first root is in the soil profile and by looking at the root flare. The first order roots should be within one inch of the soil surface when planting. This doesn’t mean that it can’t be planted a little high but it must not be any lower. The root flare is the base of the tree that flares just before the roots begin. If you look at a tree and it resembles a telephone pole going in the ground with no flare, it has been planted too deeply. There is little a homeowner can do to remedy these situations in maturing trees.

The arborvitaes I visited were planted as a screen for privacy. They are great for this purpose being evergreen, full and typically quite hardy. I do not recommend planting just one species for a screen however because often this causes higher disease pressure.

Diseases are often host-specific so if you have all of the same tree species in a line, a disease will affect every one of them in quick fashion. This could result in the loss of all of the trees in the screen! If you have several species of trees in the screen, then there is a greater chance you will only lose a couple of them, thus sustaining your privacy even in the midst of a problem. This was not the problem in this instance, a storm had blown many of the trees around and uprooted a few of them. In an attempt to stabilize the roots, the homeowner added soil and bagged concrete on either side of the trees. This effectively suffocated the trees and caused them to die a fairly slow death. The decaying trees allowed for a wood decay fungus called armillaria to be present. This can affect nearly all types of woody vegetation. In this instance, it caused the death of several more of the arborvitae trees.

There is a better way to shore up a loose root system after planting or after a storm. I do not care for guy wires attached to anchors in the ground. I see this frequently but often; these are left too long and begin to girdle the tree as it grows. Girdling cuts into the tree’s vascular tissue that conducts nutrients, water, and sugars from soil up to the leaves and back down to the roots. Instead, use 2”x2” untreated wood to drive stakes on either side of the root ball. Then using drywall screws, attach another 2”x2” piece to your stakes that is firmly pressing down on the root ball. This allows for stabilization of the root ball while allowing roots to re-establish and builds bracing wood in the base of the tree. This process will actually strengthen the tree to better withstand higher winds in the future.

The last instance for our story this week was the pecan orchard. This was a beautiful place with roughly 75 pecan trees in the orchard and they are approximately 35 years old. Most of them looked great, but several were showing signs of root trouble. The main sign that points to root issues is when you notice severe thinning in the top of the tree. In discussing the history of the orchard, it was revealed that a family member disced the soil with a fairly heavy disc. Most of our trees have nearly all of their roots in the upper six to ten inches of the soil profile, discing over them will cut a good portion of the main roots. The family member, in an attempt to make it look and drain better, leveled the area out with a box blade. This put fill material over the roots and suffocated the trees.

Tree roots have to have to have oxygen. This is one reason that flooding is such an issue on trees, it takes away the oxygen supply to the roots. Adding just three inches of soil over tree roots has the same effect. There is no longer gas exchange through the soil profile. The result is a long slow suffocation of the tree over a three-to-five-year period. The trees, in an effort to survive, put out adventitious roots that tend to circle the tree. If the lack of oxygen to the roots doesn’t kill the tree often these circling roots will. By growing in a circular pattern, they grow into and sever other roots and can even girdle the tree trunk just like using guy wires. It may look pretty and be easier to mow but is it worth losing the trees?

If you have horticulture a question, call the Extension Master Gardener Volunteers in Beaufort County or Gene Fox, the Area Consumer Horticulture agent at (252)946-0111 or please email Gene at gene_fox@ncsu.edu. Our Extension Master GardenerSM Volunteers in Beaufort County offer their Greenline service on Mondays and Wednesday from 10:00 – 12:00. Give us a call and let us help you GROW!