Tree Care Tips and
Frequently Asked Questions
Frequently Asked Questions About Basic Tree Care Practices
Frequently Asked Questions About Storm Damage, Tree Defects, and
Hazards
Frequently Asked Questions About Trees and Construction Damage
Frequently Asked Questions About Selecting and Planting Trees
Frequently Asked Questions About Tree Health
Frequently Asked Questions About Basic Tree Care Practices
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I
have a new house and have never cared for trees before. What do I need
to know?
-
What
are some of the benefits of maintaining my trees?
-
My
neighbors have told me that installing mulch rings around trees is
good. Is that true?
-
Can
my tree really be damaged by a lawn mower?
-
Why
should my trees be pruned?
-
How
do I know if my arborist will prune it correctly?
-
I
have a newly planted tree. Should I prune it?
-
I
have two different recommendations from arborists on how to prune my
newly planted trees. Why is this?
-
Should
I prune a young, established tree or is it better to just let it grow?
-
A
neighbor said my tree care company should have used pruning paint to
seal the cuts. Is this correct?
-
How
do trees close pruning wounds? Why didn’t my tree care company cut
the limb right back to the trunk?
-
Should
I have my tree topped?
-
Should
I have my trees lion’s tailed?
-
When
is the best time to prune trees?
-
My
neighbor said I should only prune trees in fall or winter. Is this
true?
-
Do
my trees need water?
-
Should
I fertilize my trees?
-
How
does the arborist determine when to fertilize? Why does my tree need
a soil test?
-
The
arborist said the problem with my tree isn’t lack of nutrients but
soil pH. What does that mean?
-
How
do I know if the arborist is using the correct type of fertilizer at
the correct rate? What is the fertilization standard, ANSI A300 - Part
2?
-
What
is a nutrient deficiency and why does it need to be corrected? What
is iron chlorosis?
-
Can
competition from other plants harm my tree? What is allelopathy?
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When
is the best time of year to perform basic tree care operations?
-
What
is a tree?
I
have a new house and have never cared for trees before. What do I need
to know?
It is best
to have a professional evaluate your trees and see what recommendations
are made. The following questions and answers cover some common recommendations
and maintenance practices that will benefit most trees.
What
are some of the benefits of maintaining my trees?
Trees in
the urban/suburban landscape have traditionally been valued for their aesthetic
qualities and shade they produce. Especially in settled areas, trees have
many other important benefits.
Trees enhance
property values. Research shows that the value of your property could increase
up to 25%, depending on the size, type, location and health of its trees.
Mature trees are particularly valuable. Therefore, it makes sense to protect
your tree investment with proper maintenance. You may wish to document
the value of your trees with photos and a professional landscape appraisal
for insurance and tax purposes.
Landscape trees
can help you save money and live more comfortably. With properly placed trees
around your house, depending upon where you live, you can reduce winter heating
bills up to 15%. A mature shade tree can block up to 90% of solar radiation,
which could translate to a significant reduction in your home cooling cost.
Trees act as windbreaks and sun screens. They reduce air pollution by producing
oxygen through photosynthesis and reduce noise pollution by acting as sound
barriers.
Studies show that
trees have beneficial psychological effects on humans. They decrease stress,
inspire minds and break emotional barriers. Around the workplace, they tend
to lower absenteeism and improve productivity. Many hospitals and nursing
homes have beautiful green trees around them, and evidence demonstrates that
trees can speed recovery from illness and are good for your health.
Landscape appraisals
can help you determine the value of your trees. A knowledgeable arborist
is the best person to do appraisals. Just as a competent auto mechanic can
point out needed maintenance that you might not notice, a competent, professional
arborist can offer diagnosis and preventive maintenance to keep your trees
in top condition.
My
neighbors have told me that installing mulch rings around trees is
good. Is that true?
Yes, trees
love mulch, if applied correctly.
Mulches
Homeowners
and professional arborists depend on mulch in landscapes for several reasons.
Functionally, mulches discourage weeds from growing, conserve
moisture during drought periods, and allow better use of water by
controlling runoff and increasing water-holding capacity of light, sandy
soils.
Mulches help maintain
a uniform soil temperature. A 3- to 4-inch layer of mulch can add
to the aesthetic value of a garden while protecting the base of
trees from being injured by equipment, such as lawn mowers.
Mulch rings also decrease
competition from lawn grass. Lawn grass, especially when lush, robs
trees of valuable nutrients and moisture.
Many organic materials
can be used as a mulch. Bark mulches and wood chips are the two most commonly
used mulches in most of the country. In the south, pine needles are included
in that list.
Mulch can be applied
just about any time of the year when trees and shrubs are being planted.
The best time, however, to apply mulch in established bed areas would be
in mid-spring when the soil temperature has warmed up enough for sufficient
root growth. If applied earlier, the mulch will keep the soil temperature
lower and root growth could be delayed.
Mulches should
be applied 2 to 3 or 4 inches in depth over relatively clean, weed-free soils.
Do not pile mulch more than 4 inches. Identify and eradicate the weeds before
the mulch is applied. Keep mulch pulled 12 inches back from the tree trunk.
Most arborists
consider organic mulches as the most compatible with trees. There are, however,
several inorganic materials used as mulches. These include weed barriers.
Black plastic
is sometimes used to discourage weeds, however it interferes with the normal
oxygen and water supply to the tree’s roots. When the plastic is used, a
very shallow root system is created and during drought periods the plants
may not withstand the stress. It
is recommended not to use black plastic around trees.
There are, however,
several landscape fabric “mulches” available that will function
the same as plastic, but allow for normal water and oxygen exchange. These
materials, sometimes called geotextiles or weed barriers,
are placed on bare soil around trees and shrubs with mulches used on top.
There are many brands and types of materials from which to choose. They have
proven to be beneficial in discouraging weeds and conserving soil moisture.
Can
my tree really be damaged by a lawn mower?
Yes, trees
often are wounded by careless use of yard equipment like lawn mowers,
weed whips, and other trimming equipment. These injuries cut through important
vascular tissue just inside the bark, which can lead to decay and ultimately
death of the tree. A bed of mulch around the tree eliminates the need to
trim or mow close to the tree's base. Extreme care should be taken when
digging up or tilling the soil under a tree. Many large and small roots
will be cut by such digging, especially if it occurs close to the trunk.
Why
should my trees be pruned?
Pruning
trees, especially when younger, helps promote healthy trees with good branch
architecture. Again, think of a tree in it’s native environment, the forest.
There the tree is in stiff competition with other trees. It is forced to
grow fast and upright to fill what is usually a very limited space. Trees
growing in man-made conditions usually have much more space and less competition.
They will spread out to form much broader trees than they would if located
in the forest. The branch structure will often be inadequate if the tree
is left to develop on it’s own. These trees can develop hazard limbs that
eventually could fail, leading to an early tree death.
Tree
Pruning:
-
promotes good
branch structure,
-
can
correct poor branch structure,
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reduces
potential hazards,
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improves
overall health by removing dead, diseased, and dying branches,
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gives
the arborist a chance to examine the tree more closely than possible
from the ground.
How
do I know if my arborist will prune it correctly?
Ask the
arborist if they prune according to the American National Standards Institute
standard for tree pruning, called ANSI A300
- Part 1 Pruning.
ANSI
A300 Part 1 Pruning
This standard
requires that the recommended use of certain tools, cutting techniques,
and pruning methods be followed and sets the standard definitions for terms
the arborist will use in your estimate. Estimates
for tree pruning should be written in accordance to ANSI A300 standards. Properly
written ANSI A300-Part 1 Tree Pruning work estimates should include,
at a minimum, the following information:
-
a statement
that says all work will be performed in accordance with ANSI A300.
-
a statement
with a clearly defined pruning objectives,
-
the
type of pruning to be performed,
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size specifications
of the minimum and/or maximum branch size to be removed.
In addition
to the information given on the work estimate, ANSI A300 Part 1 Pruning sets
some guidelines for basic pruning practices that arborist should follow.
If an arborist is adhering to the ANSI A300 Part 1 Pruning standard
they:
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will
not leave branch stubs,
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will make
few or no heading cuts,
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will
not cut off the branch collar (not make a flush cut),
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will
not top or lion’s tail trees,
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will
not remove more than 25% of the foliage of a single branch,
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will
not remove more than 25% of the total tree foliage in a single year,
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will
not damage other parts of the tree during pruning,
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will
not use wound paint.
I
have a newly planted tree. Should I prune it?
It is generally
recommended that some limited pruning be done at the time of planting.
Newly
Planted Trees
Generally,
when a young tree is planted, dead, broken, and split branches should be
removed.
Once the
tree is established (up to one year or more after planting) a central trunk
or leader or well-spaced multiple trunks or leaders should be developed
by removing competing leaders and heading or thinning vigorously growing
branches that compete with the selected leader(s). Branches should be retained
on the lower trunk to increase taper.
I
have two different recommendations from arborists on how to prune my
newly planted trees. Why is this?
Some arborists
prefer to limit the amount of pruning done to a newly planted tree to give
it a chance to get established. In this case the pruning will be limited
to dead, dying, or diseased branches. This is the best option if the arborist
will continue to care for the tree, making return visits in the future.
Other arborists
may recommend pruning to shape your tree for good branch development at
the time of planting. This is probably the best option if no additional
care will be given to the tree in the near future.
Should
I prune a young, established tree or is it better to just let it grow?
It is important
to prune young trees in order to develop a strong scaffold branch structure.
Pruning of young trees can avoid more expensive problems that could occur
if the tree is allowed to grow with branch defects.
Pruning
cautions
Many tree
problems, and even maintenance requirements, can be avoided by knowing
the growth habit of a specific tree. Find out how fast and how
large a tree normally grows. See Select and Plant.
Logic and
reason also apply. For example, don't plant a white oak directly beneath
utility lines. As the tree grows and interferes with the lines, the tree
will be pruned. This could destroy the natural character of the tree and
lead to its early decline and death.
Warning:
Home owners should limit their tree pruning to small, lightweight branches
which can be reached from the ground or they could subject themselves
to severe injury and even death.
The
pruning of large branches and/or working off the ground should be left
to professional tree experts with proper equipment.
A
neighbor said my tree care company should have used pruning paint to
seal the cuts. Is this correct?
In the
past, part of the standard recommendation was to apply a generous coating
of a tree wound dressing to all fresh cuts. It was believed this
would prevent decay-causing infection. However, research by the United
States Forest Service Northeastern Forest Experiment Station proved that
this practice works against nature's design and the trees' best interest.
Research has proven that all of the wound dressings currently available do
nothing to prevent decay, and some serve as a food source for microorganisms.
They also can hold moisture against the cut wood, promoting the growth
of decay-causing microorganisms. A light coating of non-toxic wound dressings
can be used for cosmetic purposes.
Wound dressing
may also be recommended in some unique, limited situations, such as to
control mistletoe or to discourage borer infestation that could spread
diseases like Dutch Elm Disease. Consult your arborist for more
information.
How
do trees close pruning wounds? Why didn’t my tree care company cut
the limb right back to the trunk?
When a
tree is wounded, it sets up defensive walls against the invasion of decay
fungi and other microorganisms. The vessels near the wound are plugged
with gums, resins, and chemicals that resist the spread of decay. This
creates protective walls within the tree. When decay develops in a branch,
it moves down the branch until it reaches the protective walls. Once there,
it stops.
Generally,
if the tree is healthy very “strong” walls can be erected and the decay
can be stopped. If a tree is not healthy, it’s wall will not be as “strong.”
Some trees have “genetically weaker” walls and do not do a good job at
stopping decay.
After initially
forming the “walls,” the tree then attempts to cover over the wound with
what is called woundwood.
For branches
and limbs, a region called the branch collar is where this protective
chemical zone is located. The branch collar is located at the base of the
branch or limb. Sometimes it can be seen as a slightly swollen area.
When
the branch collar is removed during pruning, such as when a cut is made
flush to the trunk, it is called a flush cut. Flush cuts greatly increase
the chance of the trunk becoming infected by decay and canker-causing
microorganisms. Removing the branch collar
(making a flush cut):
-
removes the
protective chemical zone;
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exposes
the trunk to decay organisms;
-
and
creates a larger area for the woundwood to cover, exposing the wound
for a longer period of time.
A properly made
pruning cut, called a collar cut, leaves the branch collar in tact.
This results in a doughnut-like ring of woundwood forming all the way around
the wound. With this type of pruning cut closure may take only a few months
for small wounds.
Larger wounds
may take years to close, or may not close at all.
Should
I have my tree topped?
The short
answer is no. Topping, tipping, heading back and dehorning are all terms
used to describe severe cutting back of a tree's crown. It is a poor arboricultural
practice and should not be used for healthy tree maintenance.
Topping:
-
destroys the
trees branch structure
-
gives multiple
points of entry for wood decay organisms
-
can turn your
tree into a hazard, creating a liability for which you could be held
responsible
-
does not limit
tree growth as advertised by tree toppers.
Though
topping often leads to many large, fast-growing sprouts, these sprouts
are attached to stubs that soon become rotten. The sprouts then become
hazards as they grow larger.
The common
reason given for topping is to limit the growth of a tree, but this does
not occur. In reality, the fast-growing, vigorous watersprouts will actually
outgrow a similar-sized tree that has not been topped in about 5 years
after the topping.
Should
I have my trees lion’s tailed?
Again the
short answer is no. Lion’s tailing is the “gutting-out” of a tree by removing
a large number of the inner branches. The limb’s of the tree look like
a lion’s tail after pruning. The limbs will appear “long and slender” with
a “puff” of foliage at the end.
Lion’s
tailing:
-
is
a form of over-pruning, too much foliage is removed so that the health
of the tree could be jeopardized;
-
leaves
too much weight at the end of the branch;
-
exposes
the inner portion of the tree to sunburn and growth of watersprouts;
-
may
make your tree a hazard since the branches may become weak and break
Tree pruned
according to ANSI A300 Part 1 Pruning standards cannot be lion’s tailed
because not more than 25% of foliage can be removed in a single year and
50% the foliage should remain evenly distributed in the lower 66% of the
canopy.
When
is the best time to prune trees?
The old
arborist saying goes, “the best time to prune is when the pruners are
sharp.” Meaning that trees can be pruned at any time. This is
still true for most trees, although there are some points to consider and
some limited exceptions to the rule.
My
neighbor said I should only prune trees in fall or winter. Is this
true?
Pruning
trees does not have to be limited to fall or winter. Granted, fall and
winter are good times to prune as the tree is dormant.
Points
to consider when deciding when to prune:
- Spring flowering
trees can be pruned as soon as the leaves turn dark green and harden to
avoid cutting off any of the following year’s flower buds.
- Summer flowering
trees can be pruned before new growth begins in early spring to avoid cutting
off any of the current year’s flower buds.
- Palms are often
pruned in the spring so that flower stalks can be removed before they produce
messy fruit.
Birches,
dogwoods, elms, hackberries, magnolias, maples, poplars, walnuts, willows,
and a few other trees are known as "bleeders". When these species are pruned
in late winter or early spring, the wounds may bleed. This flow of sap
is more unsightly than damaging to the tree. In fact, sap at this time
of year is roughly 98% water and 2 % sugar, so little energy is lost through
a bleeding wound. The sap flow will taper-off and cease as the new leaves
turn dark green and harden. Pruning these trees could be delayed until
the leaves turn dark green and harden if you have aesthetic concerns.
Exceptions:
There are
a few trees susceptible to insect and disease problems that could be encouraged
if pruning is done at the wrong time.
The most
common example is Dutch Elm Disease. This disease has devastated
the nation’s population of American elm trees. The fungal disease is spread
primarily by the elm bark beetle (elms growing close together can spread
the disease through their roots). The beetle is attracted to fresh pruning
cuts when it is active in mid to late spring and early summer. It bores
into the wood, spreading the fungal disease. Pruning of susceptible elms
should not be done during this period to avoid attracting elm bark beetles.
Similar
diseases and infestations carried by boring beetles, but less widespread
than Dutch Elm Disease, are Oak Wilt, most serious in the Mid-West
and Texas, and Pine Wilt Nematode and Blue-Stain Wilt of
pine, most serious in the Southeast.
Eucalyptus
borer infestations can be a problem for eucalyptus trees in the western
United States.
Tree care
professionals may recommend that pruning of susceptible pines, oaks, and
eucalyptus trees be avoided 1) when boring beetles
are active and 2) if diseases they might carry are prevalent in your area.
Fireblight is
a very different disease, but it’s spread can be avoided by correct timing
of pruning. Fireblight is a bacteria that infects ornamental and fruit
trees in the Rose family. It is most serious on apples, crab apples, and
pears. The disease is spread by rain water, especially when the trees are
in flower. Avoid spreading this disease by not pruning when these trees
are in flower or when it is raining.
Similar
diseases spread by rainfall are Cytospora Canker of spruce, most
serious in the northern tier of the United States. Avoid pruning spruce
when it is raining if Cytospora canker is a problem in your area.
Avoid pruning
these trees during rainy weather:
Do
my trees need water?
That depends.
Your trees will need watering if they are newly planted or your area is
suffering from drought conditions. If you are receiving normal or close
to normal rainfall for your area, then you should not have to water your
established trees.
Exception: If
you live in a dry or desert area, or have sandy soil, and someone has planted
a tree not suited for these conditions, then the trees may require more
water than even normal rainfall can provide to survive. Depending on the
cost and availability of water in your area, it may be better to replace
such trees with others better adapted to your local environment. See Selection
and Planting of Trees.
Installing
mulch will conserve soil moisture and reduce the amount of water needed.
See Mulches.
If you
are installing an irrigation system you need to consult a professional
arborist to be certain that first, the installation will not harm existing
trees, and second, that the irrigation programming is set for the tree’s
watering requirements, not just the turf grass.
Watering
Moisture
is critical to trees, but too much moisture can cause serious damage. The
amount of water to apply depends on the tree.
Watering
newly planted trees:
Watering
should be done at the time of planting to settle the soil and to assure
adequate soil moisture. The first watering is normally done by the planting
crew soon after planting. After the first watering, adequate water must
be provided by the property owner unless there has been sufficient rain
to keep the soil moist. The critical months for watering are May through
September (this period of time may be extended in warm climates).
Selecting
the proper plant is very important for dry, desert-like climates to avoid
heavy watering requirements. It is usually recommended to choose plants
that are suited for dry conditions, this type of landscaping is called xerophytic.
Most trees
need to be watered for 2 or 3 years after transplanting to provide adequate
soil moisture while root systems are becoming established. In the past
it was recommended that a “saucer” be formed around the soil ball to make
a water-holding reservoir. Recent studies have shown that this practice
actually encourages roots to stay in the area of the soil ball instead
of growing into the surrounding soil. This can increase the time it takes
for the tree to get established in the landscape. It is now recommended
that the root ball and surrounding area of a newly transplanted
tree be watered.
To determine
the level of moisture, remove a small amount of soil at the edge of the
ball with a hand trowel and squeeze it. If you can form a moist sticky
ball, it is too wet. If it crumbles like chalk, it is too dry.
You must
provide enough water to keep at least the top 4 inches of soil moist. The
exact amount of water needed will vary.
A 3-inch
diameter tree moved by a tree spade may require 60 to 80 gallons of water
every 10 days if rain does not occur.
Distributed
soils are frequently high in clay subsoil and tend to drain poorly. If
these conditions exist, watering for a prolonged period of time may result
in over watering and cause the roots to drown from lack of adequate soil
aeration. Adding large quantities of water too frequently to heavy clay
soils is detrimental and will result in death of the tree. Conversely,
waiting until the tree wilts and the leaves start to turn brown is too
late to water.
Watering
established trees:
Large trees
can be watered with lawn sprinklers. Apply water at rate of 1 inch per
watering, 2 inches if there is vigorous lawn grass near and under the tree.
Water at a rate low enough to keep water from running off.
Do not
water daily, this can damage your tree by suffocating it’s roots. Instead
plan your watering based on the severity of the drought conditions. Generally
anywhere from once every two weeks to once every 4 to 5 days will suffice.
Most tree
roots are not very deep (within the upper 4 to 8 inches of soil), and deep
roots will receive water if enough is applied to the soil surface.
Tree roots
can extend away from the tree at a distance as far as the tree is tall,
and in many cases much farther. Therefore, it is usually beneficial to
water the entire yard to be certain the tree is watered. You can also alternate
the sides of the tree you water, from one watering to the next, making
tree watering easier while conserving water.
Should
I fertilize my trees?
Trees often
require fertilization at some point in their life span. Remember, most
tree’s natural environment is the forest. There nutrients are continually
recycled as leaves and other plant, and even animal material, fall and
decompose on the forest floor. When you put a tree in a landscape setting
it is usually deprived of these nutrients.
One thing
you can do is try to recreate the tree’s natural environment by providing
mulch rings. See Mulches. Most people, however, will not be able to mulch
their whole yard! Fertilization is needed by many trees to replace the
nutrients they are missing.
Fertilizing
Shade trees,
like any other landscape plants, will respond to fertilization. Most shade
trees exist in nature without much care, but transplanting trees into urban
areas or man-made conditions can create problems. Often these trees will
be growing in restricted root zone areas, be surrounded by pavement or
compacted soil or even be physically damaged by construction activities.
One should realize that the root system is just as important (and delicate)
as the above ground parts.
Fertilizer
alone will not improve the health of a tree stressed by one of these environmental
conditions. Fertilizer is only one factor in the complex formula of plant
requirements. See Plant Health Care.
Here’s
how to detect if your tree needs fertilizing.
Symptoms
of a nutrient deficient tree include:
-
a slow
rate and low amount of annual growth on twigs and trunk,
-
smaller
than normal foliage,
-
off-color
foliage,
-
increased
amounts of dead branches,
-
tip-die
back in branches,
-
and
increased rates of disease and insect problems.
Trees that
possess these symptoms generally would respond to a fertilization treatment.
One should make sure that nutrients (or lack of) are the problem before
fertilizing. Other common tree disorders to be aware of in urban areas
would include poor planting techniques, moisture problems, construction
damage, girdling roots, or utility leaks from a natural gas line or sewer
line.
How
does the arborist determine when to fertilize? Why does my tree need
a soil test?
Arborists
have a number of tools at their disposal. The best is the arborist’s knowledge
of local soil and environmental conditions. The arborist may be able to
make a fertilization recommendation simply by examining your tree and yard.
This saves the client time and money. On other occasions the problem may
be more complex and the arborist will recommend a soil and/or foliar analysis
to determine the problem.
Your arborist
does know that most shade trees growing in landscape settings will need
nitrogen. Nitrogen is not stable in the soil. It is easily washed away
by water and may periodically need to be replaced.
The
arborist said the problem with my tree isn’t lack of nutrients but
soil pH. What does that mean?
Before
recommending a fertilizer, the arborist may note that other problems need
to be addressed. An improper soil pH often makes it more difficult for
a tree’s roots to absorb needed nutrients, even when those nutrients are
abundant in the soil. Generally a pH range of 5.2-6.2 is the most desirable.
Acid soils are sometimes limed to raise the pH, but more commonly, basic
soils are treated with sulfur to adjust the pH downward. Maintaining a
soil pH range of 5.2-6.2 for shade trees generally insures that essential
plant nutrients will be available to the tree.
How
do I know if the arborist is using the correct type of fertilizer at
the correct rate? What is the fertilization standard, ANSI A300 - Part
2?
First,
ask the arborist if they are applying fertilizer in compliance with the
American National Standards Institute standard for tree fertilization,
called ANSI A300 - Part 2 Fertilization.
ANSI
A300 - Part 2 Fertilization
This standard
requires that certain types, rates, and application methods be followed
and sets the standard definitions for terms the arborist will use in your
estimate. Estimates for fertilization should be written in accordance
to ANSI A300 Part 2 Fertilization standards.
Properly
written ANSI A300-Part 2 Fertilization work estimates should
include, at a minimum, the following information:
-
a statement
that says all work will be performed in accordance with ANSI A300 Part
2.
-
a statement
with a clearly defined objective for the fertilization,
-
the
type of fertilizer to be applied,
-
the
rate of fertilization,
-
the
timing of the fertilization,
-
the
method of the fertilization,
-
the
fertilization area
Commonly,
the preferred type of fertilizer is slow-release fertilizer with
a nutrient ratio of 3:1:1 or 3:1:2 for shade trees, and 3:1:3 for palms.
The preferred rate of fertilizer for slow release is between
2 to 4 pounds of actual nitrogen (N) per 1000 square feet. Usually, it
is recommended to avoid applying over 6 pounds of nitrogen in a single
year. The fertilization area is basically the root zone of the
tree. The fertilization area is generally considered to be from near the
trunk to near or beyond the shade canopy (dripline) of the tree. Roots
can grow much further from the tree, however, so the arborist may recommend
adjusting the fertilization area to account for larger root zones.
There are
a number of fertilization methods such as a granular surface application,
sub-surface dry application, and sub-surface liquid fertilizer injection.
Generally, when a turf or ground cover is growing in the fertilization
area, a sub-surface fertilization method is preferred.
Your arborist
may deviate from these common practices for a number of reasons, such as
to correct a nutrient deficiency or to correct other plant health
problems. The objective of the deviation should be clearly stated in writing
on the work estimate.
What
is a nutrient deficiency and why does it need to be corrected? What
is iron chlorosis?
Just like
people, trees can have nutrient deficiencies that lead to problems. The
deficiency may cause the tree to exhibit predictable symptoms that the
arborist can use to diagnose the problem. Other times testing and analysis
may be required to determine the exact nature of the problem.
Here is
an example of a common nutrient deficiency. Many trees suffer from iron
deficiency induced by poorly drained or compacted soils or by soils with
a high calcium content. These soils are characterized by pH levels above
7.5. The unavailability or non-utilization of iron commonly causes a condition
called iron chlorosis, and is characterized by yellow leaves, slow
growth, and branch dieback.
Pin oak
and silver maple frequently show this condition.
Chlorotic
trees exhibit partial or complete yellowing of the leaves. The yellowing
first occurs between the veins, leaving a network of darker green veins
on a greenish-yellow background More severe symptoms include smaller than
normal leaves that turn pale yellow and develop angular brown spots between
the veins. Leaf margins may turn brown. The leaf eventually curls, dries
up, becomes entirely brown, and falls. Tips of affected branches may die,
especially in the tops of broadleaved trees. If the condition is not corrected,
it can cause poor root development, severe stunting, and plant death. Weakened
plants also are very susceptible to other diseases and insect infestations.
On junipers, pines, and other evergreens, chlorosis usually develops as
an overall yellowing of needles.
Cause
of Iron Chlorosis
Under alkaline
conditions (soil pH above 7.0), iron changes to insoluble forms that are
less available to growing plants. Iron is more soluble and most readily
absorbed from the soil at a pH range of 5.0 to 6.5. Lack of available iron
is aggravated by: 1) low temperature and high soil moisture, 2) relatively
large amounts of copper, manganese or zinc, and 3) excessive phosphorus
applications.
Correcting
Iron Chlorosis
There are
three methods of applying iron salts to correct iron chlorosis in plants.
They are: 1) applying a mixture of dry ferrous sulfate (iron sulfate) and
sulfur to soil, 2) spraying the foliage with a solution of ferrous sulfate
or iron chelate, or 3) introducing iron salts into the main stem or trunk
of affected plants by implantation or injection.
This is
a case where the arborist might recommend a foliar spray or trunk injection
to save the tree in the short term, and then recommend other treatments
to correct the real cause, the high soil pH, in the long term.
Can
competition from other plants harm my tree? What is allelopathy?
Often little
thought is given to the effects of altering plant communities. For example,
it is uncommon to see an attractive sugar maple growing in an attractive
bluegrass lawn. Either the healthy sugar maple shades out the grass or
the tree slowly declines due to competition from the lush, highly competitive
grass.
Allelopathy,
the release by one plant of substances toxic to nearby plants, can also
be a factor. Some allelopathic relationships, such as the effects of walnut
on rose, are well known, but many are poorly understood.
When
is the best time of year to perform basic tree care operations?
Many tree
care activities can be carried out all year long. For other activities
there is a season.
Spring
and summer give us the best opportunities to identify tree health problems,
since a cursory inspection can tell whether the tree "looks" healthy compared
to previous years or nearby trees of the same species. Diagnosis of the
actual cause of the tree malady is a tricky business best left to an expert.
As with human illness, prompt detection and treatment can be critical.
Most pest
management activities have a very specific and narrow window of treatment
that coincides with when the pest is active on the plant and/or vulnerable
to the treatment. Fertilizers are best applied when
the plant roots can actively uptake the nutrients. Of course, the use of
fertilizers on shade and ornamental plants should be restricted to situations
in which there is a nutrient deficiency.
Some will
argue that, in temperate areas, fall and winter are the best times to prune.
When the tree is bare, its branch architecture is easier to observe, so
problems can be more readily corrected. Proper
pruning at other times of the year will generally do no harm to trees,
but there are exceptions. For instance, pruning an American elm when the
beetle that carries Dutch elm disease is busy flying from infected to healthy
host trees greatly increases the elm’s chances of infection. Pruning of
deadwood only does not have the same effect and can be carried out any
time.
What
is a tree?
A tree
is a complex, living organism. There are many different definitions for
a tree and for each you can probably think of some exceptions. Webster’s
defines a tree: 1 a : a woody perennial plant having a
single usually elongate main stem generally with few or no branches on
its lower part. It also defines a shade tree: a tree grown primarily
to produce shade.
In general
it can be said that trees:
-
Are perennial
plants
-
Have
relatively long life spans
-
Have
woody trunks
-
Have
bark for protection
-
Have
leaves to produce their own food
-
Have
roots to gather water and mineral nutrients
Specifically
trees can be divided into three categories:
1. Conifers usually have:
-
Cones, or
cone-like structures, instead of flowers
-
Evergreen
leaves that are needle-like, scale-like, strap-like, or awl-shaped (there
are some conifers that shed their leaves every fall, these trees are
termed deciduous)
-
Soft wood
2. Shade
trees usually have:
3. Plants
that grow like, or are trained to grow like trees. Examples:
-
Palms
-
Tree Ferns
-
Tree Hydrangea
Interesting
Note: Palms are routinely considered trees, although technically they are
more closely related to your lawn grass than any shade tree or conifer!
