We had record attendance for Master Arborist Chuck Lippi's presentation on human causes of tree decline. We and our seven guests, including four Master Gardeners, learned a lot and as usual, there were more questions than the one hour presentation could accommodate.
Here is a summary of the highlights in the Chuck
Lippi annals of awful arboriculture. Sadly, these examples were the
norm, not the exception. The effect, tree decline, only manifests itself much later - meaning there is no temporal relationship. Diagnosing the cause of a tree's decline is a little like diagnosing
the cause of our own flu, cold, or other illness. Too many of us only look at the symptoms. It takes a
trained professional like Mr. Lippi to thoroughly examine the patient before a definitive
diagnosis (and treatment) can be made. Non-Specific Symptoms
Trees that
are stressed by poor maintenance don't look healthy. They may show
dieback in their growing areas, such as the crown or growth tips. They
may sprout leaves directly from their trunks instead of on their
branches (where they'd be more effective obtaining sunlight). Branches
may fall off or die off in situations which wouldn't normally cause them
to be lost. Bark may come off easily. Or, one day, the tree may just fall down.
Nobody wants to get a call from a neighbor saying that their tree just
fell on the neighbor's car-house-husband... Better maintenance might
have prevented such accidents. Of course trees do die of old age. For
instance, live oaks measure their lifetime in centuries, but laurel oaks
in decades. Removing a tree near the end of its life expectancy is
sometimes sad, but not as sad as seeing it damage property or hurt
people. The Roots of the Problem
Constriction:
Improper planting is one of the leading causes of tree decline; if the
roots, which are part of the tree's vascular system, are warped, cut, or
constricted, the tree's ability to take up water and soil nutrients will
be compromised . Often nursery-grown trees stay in one container too
long, causing the roots to grow into a tight ball. Unless the root ball
is opened up when planting, the roots will continue to grow as a ball
and ultimately strangle the tree or fail to anchor it in the ground. Science is still formulating best
practices on how to mitigate the trend when planting. Current
recommendations say to shave the exterior of the ball so the roots can
grow outward. Despite there being some controversy over the best method
of freeing the rootball, nobody recommends leaving the roots bound up
in rope or cord, least of all synthetic cord. Planters too busy
(translation: lazy) to remove the restraining cord around the roots,
sentence the tree to a shortened life span. The roots may grow around
and/or over the rope, but the rope impedes nutrient uptake which
stresses the tree. In extreme cases of self-strangulation by the tree's
own roots, the taproot will grow around the trunk like a noose.
Root-bound containerized trees make poor long-term investments.
Asphyxiation:
In addition to absorbing nutrients, roots take in oxygen. If the tree
is planted too deeply, the roots will be unable to breathe and it will
probably decline. Soil immersion is not the only cause of asphyxiation,
however. Notice how many parking lots are constructed around large
trees? The roots are are probably damaged, not only because heavy
vehicles drove over them during construction, but because they are now
buried in a layer of impervious concrete or asphalt. Sometimes you'll
see the roots emerging from their covering in a last-ditch attempt to
get oxygen. The typical result is that the parking lot or sidewalk is
"repaired" by repaving. But you don't have to cover the roots in
concrete to kill the tree. Over-mulching, especially when the mulch is
piled up against the trunk (called volcano mulching) can cripple a tree.
Not only does the excess mulch deny the roots access to air but piling
mulch around the trunk encourages fungus and other moisture-loving
bark/trunk diseases. Mulch is commonly thought of as a weed-suppressant
but applied too deeply, it can provide an organic stratum that invites
weed seeds to germinate and to rob nutrients from the roots.Root problems announce themselves in the non-specific way most other tree issues do. And buried roots tell no tales. But the mere fact that you can't see the root flare (a swelling where roots join the trunk that is visible at the soil surface) on a mature tree should tell you that something is amiss. See these links on how to correctly plant a tree and what can happen when you don't.
A Shave And a Haircut Are Not Pruning Techniques
The Spring Shearing:
It's a popular misconception that trees "like" to be "pruned," just like
grass "likes" to be cut. It "encourages" them to grow faster. Like a
gun would "encourage" us to work faster. We cut our grass when it's too
long; we shear our trees when they get too big. Planting a smaller
tree would be the better solution for the tree and give the owner more
time to enjoy the appropriate-sized tree. Southern Living magazine has
an annual contest in observance of the too-common practice of " crepe murder." The University of Florida has advice for pruning crepe myrtles appropriately and descriptions of what can go awry when pruning is too vigorous.
My neighbor is going into the annals of awful arboriculture for the
stealthy way she is amputating the live oak next to her house; maybe
some day it will repay her diligence.
pruning is "hurricanes." It's true that they happen, but it's false that the tree needs regular "hurricane cuts" to save it from
being injured by a hurricane. The rationale is, "the fewer the
branches, the less wind force against the tree." What is forgotten, is
the "weaker the tree structure, the weaker the tree." For most trees,
the crown (the branching areas) should comprise 2/3 of the tree. But "overlifting" (removing too many lower branches) makes the tree top-heavy and
more prone to injury or uprooting. It may
be advisable to the best
thing to do is to trim the crown to reduce wind impact; this would consist of a light pruning that would shape the crown
more symmetrically but keep the tree canopy at 2/3 of the tree size.
If It Ain't Broke, Don't Fix It:
Doing nothing until something bad happens is not always the best decision. Some trees naturally form structurally strong branches;
others don't. Some trees form "co-dominant leaders" - that is the trunk seems to branch off. Trees with one central leader trunk are more stable structurally. This tree on the left would have benefitted from
timely pruning to remove one of the co-dominant leaders early in its life to become a single-leader tree. In nature weak-limbed trees may have loss of limbs or
shortened life spans. Trees whose limbs branch more horizonally from the trunk form stronger attachments than limbs that grow more vertical to the trunk. We don't want limb damage or breakage in the trees we plant, so if
we are willing to proactively prune the tree to a more structurally sound shape, we can enjoy such trees as redbuds or willows through their expected lifetimes.Many trees benefit from good pruning. Some don't need it for structural integrity. Know what you are getting, and if pruning is advisable, find out how and when to prune.
Although Mr. Lippi did not address the issues of fertilizer, fungicide, or insect control, he did indicate that one particular chemical, Metsulfuron methyl, present in herbicides used in the maintenance of St. Augustine grass has been implicated as a possible cause of serious live oak dieback.
Keeping your tree healthy and structurally sound helps ensure it will provide you pleasure during its normal life expectancy.
