What's Wrong With
When we were considering what questions were asked
more than any others, there was one that stood out head and shoulders
above all the rest: “What is wrong with my tree?”
Of course there is no way we can answer this question for each and
every person, but we can give you a strategy for observing your
trees which will help you determine if they have a problem and what
you may be able to do to correct it. The life of a tree in danger
can often be saved if the decline spiral is reversed.
If you suspect the health of your tree is in decline,
we advise following a course of ob-servation that examines the traits
that indicate whether the tree is getting all the re-sources it
needs, and whether it is being threatened by external forces.
The first step is to review the history of the tree.
What type of tree is it? How old is it? IS your climate zone compatible
with the tree’s needs? How long has it been on the site? What
are the elements of the hardscape such as sidewalks, curbs, decks,
pools, and sprinkler systems, that are close enough to the tree
to affect its health?
This last question is often the most crucial, because
three quarters of urban tree deaths can be attributed to root damage.
It is important to note if any digging has been done inside the
drip line. The drip line is a circle around the tree with the trunk
at its center and its circumference the outermost tips of the tree’s
leaves. Even if the digging was done over five years in the past,
it may be a significant factor in the health of the tree. Some trees,
such as the cedar, go into decline almost immediately if they suffer
root damage, while others, like the oak, may take five years or
more to show the effects of root damage, and people often fail to
associate the decline in a tree’s health with changes in its
root system. Most of a tree’s root system is within 24 to
30 inches of the soil surface, so the danger to a tree posed by
digging within its drip zone cannot be overstated.
Once the tree’s history has been reviewed, and
any changes in the hardscape noted, the tree can be examined for
clues to its health. It is recommended to start at the root crown,
because so many of the threats to the tree’s health start
there. Is the tree at “original grade”, meaning does
the tree enter the soil at the same depth at which it was planted?
Is the root crown flare above ground and in good condition? A common
mistake made by well-meaning gardeners is to cover the root crown
with soil or mulch. While we strongly recommend using mulch as a
way to conserve soil moisture and keep it friable, it is not advisable
to cover the root crown itself. This area needs to breathe, and
when it it is buried it is vulnerable to attack by insects, fungi,
and microorganisms that thrive in moist dark conditions.
The condition of the soil is an important factor in
determining the health of the tree. What is the soil’s ability
to absorb water? If the area under the tree is kept clear by frequent
raking and leaf blowing, or is subject to heavy foot or vehicle
traffic, the soil often becomes compacted and may no longer allow
water to penetrate the root zone. A tree may be exposed to adequate
amounts of water, but if the water runs off before the tree can
access it, there is clearly a hazard to the long term health of
the tree. As we stated above, we recommend a mulch of leaf, bark,
and other organic materials spread three to four inches thick within
the drip line, up to but not touching the root crown flare, as a
way of suppressing weeds, maintaining good soil conditions, and
enhancing water absorption by stabilizing soil temperature and moisture.
Mulch also feeds beneficial soil organisms like earthworms that
ventilate and fertilize the soil, and protects roots that have emerged
from the soil surface from damage by mowers, a common problem for
lawn trees. Lawn mower damage can often be observed while examining
the soil and roots, and if discovered early enough, can usually
Gardening tools can be a serious hazard to trees.
As our examination moves from the soil up the trunk of the tree,
we look for indications of weed whip damage, caused by nylon string
trimmers, which can appear as bruised or torn tissue in the bark.
This is an all too common threat to trees, and with thin skinned
species such as citrus, birch, ficus, and camellias, as well as
with almost all young trees, weed whip damage can often re-sult
in their death, as the flow of water and nutrients is cut off by
the disruption of the cambium layer.
No tree benefits from a tourniquet around its trunk,
which is why we look for tree stakes and ties that have been left
too long and are interfering with the tree’s expansion. Staking
assists in the critical establishment of many trees, as it protects
them against wind damage for the first year to year and a half after
planting. Once the tree is established, stakes and ties often inhibit
its development by preventing the natural swaying that en-ables
the trunk to expand and thicken. Stakes and ties also can cut the
the circulation in the vascular system as the tree expands around
The condition of the bark is another indicator of
the health of the tree. Bark loss is a sign of decline and indicates
an interruption of the vascular supply. It can be caused by damage
to the root system or improper pruning. There are some trees such
as eucalyptus, birch, and Chinese elm, that peel superficial bark
naturally, which is why it is crucial to identify your trees and
know their characteristics in order to observe them properly. Healthy
bark has a firm attachment to the tree and shows and shows good
expansion with fresh deposition of tissue, an indicator of the tree’s
As the examination moves up the tree, the condition
of the leaf is another gauge of the tree’s vitality. Healthy
leaves are bright, fresh, and hydrated. Curling indicates insufficient
supply of water, while yellowing leaves often indicate a nutrient
deficiency. While the loss of leaf in the interior of the tree is
a natural part of the tree’s development known as shade out
die-back, dead leaves at the tips of branches are a sign of decline
in the tree’s health. This is another condition that can be
caused by root damage or improper pruning. See our video “Prune
Like a Pro” for an in depth discussion of proper and improper
We can observe the effects of improper pruning in
the tree’s scaffold and canopy. Does the tree have a natural
and pleasing form, consistent with its genetic morphology, or has
it been forced into unnatural form by topping, hedging, and stumping
cuts? Trees with single leads such as pines and cedars should not
be given topping cuts, while multiple lead trees can be pruned back
to new laterals and new leaders if done properly. Does the tree
have natural terminals or is the form of the branches interrupted?
How much of the tree is thriving, and what percentage is declining?
By following this method of observation, you can assess
the health of your trees, and identify the forces that are interfering
with their natural vigor. Even if you can’t identify the causes
of decline yourself, an arborist may be able to help you find the
source of the tree’s problem without even coming to the site
if you have answered these questions carefully. While we can’t
answer “What’s wrong with my tree?”, we can help
empower you to answer the question yourself. The more you know about
your trees, the healthier you can help them be.
for a description of books about trees that we believe will expand
your knowledge and enhance your ability to live in harmony with
your trees, and send them into the future.