The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Community Tree Care
Edward F. Gilman
V11J I Sa^ -B ^ A -V
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida
John T. Woeste, Dean
Quick Guide to Successful Tree Care
Have a tree management plan.
Plant the right tree in the right spot.
Select large-growing shade trees with one central trunk for planting.
Plant correctly according to the latest research.
Set the football the same depth it was in the nursery.
Water regularly it's the best soil amendment.
Fertilize regularly with the right material.
Prune regularly to create a strong trunk and branches.
Never prune branches from the trunk with a flush cut.
Monitor routinely for insects and disease.
Construct a fence at the edge of the dripline to protect a tree at a construction site.
To minimize liability when planting large-growing shade trees (for example live oak), select only those which have
one central trunk. Communities which plant trees that are trained in this manner in the nursery will have lower tree
management costs and healthier trees.
Edward F. Gilman, Associate Professor, Environmental Horticulture Department, IFAS, University of Florida, Gainesville, FL 32611
Front cover: Tree roots are much shallower than we have been led to believe. Most roots are located within the
top 12 inches of soil because this is where aeration, nutrients and moisture are abundant. The tap root shown in
the drawing is usually not present on most urban trees unless soil is exceptionally well drained.
How many miles of roads does your community
maintain? How many street and traffic lights are
there? What is the condition of your community's
bridges? The answers to such questions as these
can usually be answered by the engineering depart-
ment, but few communities know the condition of
another part of the infrastructure the trees! Trees
are vital because they provide important benefits,
and they can live to be very old. Fortunately, we
are beginning to realize the value trees provide
Figure 1. Trees need care in order to provide us with the benefits.
Unlike trees in the rural forest, the trees in our
communities need care to perform their function
safely, particularly when they are young. Today,
communities often hire urban foresters or arborists
to direct the urban tree care program, but property
owners, citizens, tree care firms and municipalities
must act together as stewards of community trees.
Manage your trees with a plan
You can only manage a resource if you under-
stand it. The best way to understand the trees is to
take an inventory. A tree inventory will help
determine the number, condition, age, potential
planting spaces and other information about your
trees. Without this information you will only be
reacting to problems in the urban forest, not
managing it. The trees under a crisis management
system will suffer from lack of directed care and
long range planning.
Select the correct trees
Many communities have developed lists of trees
best suited to the area. The Florida Division of
Forestry and Cooperative Extension Service
Offices located in each county also offer tree lists.
Arborists agree, municipalities should strive for
diversity of tree species throughout the city. An
accepted rule recommends no more than 20 percent
of the trees should be from the same genus (for
example oak) and no more than 10 percent from the
same species (for example live oak). For instance, a
disaster could result if say 60 percent of the trees in
a city were live oak and a devastating insect or
disease were to strike this particular species.
Strive for diversity on a city-wide perspective;
but do not plant a large variety of different trees on
the same street. Instead, plant one section of the
city (several blocks) with one species, and another
with a different one. This allows the development
of neighborhoods which will have an identity the
Plant trees in the right spot
Tree pruning around power lines costs about 1
billion dollars each year! To help reduce this cost
plant only small maturing trees (less than 25 feet
in height) below and within 25 feet of the line.
Plant large maturing trees (greater than 25 feet in
height) at least 25 feet (preferably 40 feet or more)
from the lines. This will help keep utility bills in
check and will provide more reliable electric service
due to less tree interference with the lines.
Avoid planting large-maturing trees in areas less
than 20 X 20 feet unless soil drainage is excellent.
This small area will dwarf the tree so it will never
reach its natural size, but it is much larger than
what current standards provide. In a parking lot,
trees grow much better when grouped together in
several large planting islands than in numerous
small islands distributed over the site. Allow at
least 400 square feet of soil space for each tree.
Tree planting made easy
To allow for proper root growth into the land-
scape soil, the top of the root ball should be posi-
tioned even with or slightly above the soil surface,
never deeper (Figure 2). There is no need to add
organic matter or fertilizer to the backfill soil
around the root ball. This addition will not help
establishment unless the tree is planted in lime-
stone rock, which is common in some areas of South
Florida. Always spread a 3 inch thick layer of
mulch over the root ball to conserve soil moisture
and aid establishment.
Water the best soil amendment
Irrigating recently installed trees is difficult, but
essential. Many die or perform poorly from too
little or too much water. To establish a tree in
Figure 2. A) Never plant trees deeper than they were In the nursery. B) Plant even with the ground in well drained soil. C) In poorly
drained or compacted soil, the top of the root ball should be slightly above the soil surface; add additional soil to cover the
side of the root ball. You can't go wrong by planting shallow.
sandy, well-drained soil, from 3-to-5 gallons of
water per inch of trunk diameter are needed almost
daily in the first several months after planting. If
soil drainage is poor, less is required. Trees larger
than about 4 inches in diameter may benefit from
nearly daily irrigation for up to a year to become
established in well drained sand. Be careful not to
overwater if your site is not well drained as is
common in many urban areas. In these sites, cut
back on the amount of water applied but don't
change the frequency.
During droughts, established trees in restricted
soil spaces (such as street trees) require more
irrigation than those in open areas where root
systems can develop their normal spread. Trees in
these and many other urban situations are irri-
gated best with a micro-irrigation system which
reduces runoff by applying water at a slow rate.
Fertilizer helps to maintain healthy trees.
Fertilizing some urban trees can be difficult and
best done by an arborist. It is best to spread
fertilizer over the surface of the soil, but it can be
injected 4 to 6 inches into the soil with specialized
equipment. This technique helps reduce runoff on
sloping ground and in compacted soils. Trunk
injections and implants can be used to temporarily
correct micronutrient deficiencies in trees which
are over 4 inches in diameter and do not respond
satisfactorily to soil treatments.
Fortunately, fertilizing is usually not necessary
for trees growing in or near lawns and adjacent to
shrub beds treated regularly with fertilizer. This is
because most of the tree's fine feeder roots are
located near enough to the soil surface to utilize the
fertilizer spread on the lawn and landscape beds.
On the other hand, trees growing in confined soil
spaces such as parking lot islands will benefit from
a regular fertilization program.
Many trees respond well to a fertilizer contain-
ing nitrogen and potassium. At least 30 percent or
preferably more of the nitrogen should be slow
release. Palms and other trees may benefit from
additions of iron and manganese. Fertilizer mixes
that contain weed killers should be used sparingly,
if at all, within the root zones of trees because the
weed killer could harm the tree. Read and follow
directions printed on the label before applying
An important investment in urban tree care is in
a systematic pruning program. The advantages
include reduced costs each time the tree is
trimmed, reduced service requests, improved safety
and reduced liability, improved pest control and
healthier trees. However, less than a third of
cities in the southern United States prune trees.
Tree pruning is a special service which should be
performed by professionals. City personnel often
remove dead or dying trees, but safety and other
forms of specialty pruning are best performed by a
specialized crew, either in-house or contracted.
Homeowners should only prune from the ground.
Non-professionals should never climb a tree to
prune because of the danger of falling or injury
from pruning equipment.
* How often To prevent the need for pruning at
planting, purchase quality shade trees. Trees
should have one central trunk and branches
spaced along the trunk, not clustered at one
point (Figure 3). Prune 2 and 5 years after
planting, then place trees on a 5 to 7-year
-- x ----
b I 3x 1
Figure 3. A) Shade trees should be trained to one central trunk,
and branches should be spaced along the trunk. B)
Large-sized trees (such as oaks) with several trunks
or those with branches clustered together on the
trunk can become hazardous when they grow older.
n Safety pruning Remove immediately any
broken or dead limbs. Have an arborist remove
branches which are not well attached to the
trunk. These potentially hazardous branches
may not be apparent from the ground.
* Preventing storm damage Major storms taught
us that trees which are properly and regularly
pruned are damaged less in a storm than those
not regularly pruned. A potentially damaging
wind passes through trees which are thinned
and trained to the appropriate structure, thus
helping keep them intact in a storm (Figure 4).
* Techniques Never top a tree (Figure 5). Top-
ping is the worst thing that you can do to a tree.
Topping initiates decay in branches and makes
Figure 5. Never top a tree. Prune it to retain the natural shape.
the tree more dangerous than before it was
pruned. It costs more in the long run, attracts
insects, and is ugly. Topping does not help
prevent damage during a storm.
* Pruning around power lines Existing trees
which were mistakenly planted under or those
located close to lines can be directionally pruned
to reduce the need for topping. Instead of simply
removing the entire top of the tree which stimu-
lates rapid regrowth, selected branches are
removed to train the tree so it grows away from
the lines. This can reduce future pruning
requirements. This is a specialized technique
requiring skill and training and should only be
performed by properly trained professionals.
Figure 4. A) Trees benefit from regular thinning. B) Proper thinning removes or reduces the length of some branches from all along
the main branches. C) Improper thinning removes all Interior branches. This practice often makes the branches
susceptible to breakage.
The method of branch removal has a large
impact of tree health. Never remove a branch with
a flush cut (Figure 6); instead, use a collar cut. The
trunk is likely to decay or crack following a flush
cut, making the tree unsafe.
A B C
Figure 6. Proper pruning technique. A) Notice the swelling at
the base of the branches. This branch collar helps
hold the branch to the trunk. A proper pruning cut Is
made between the arrows. B) This shows how to
properly remove three branches from the trunk.
Always cut to the outside of the branch collar. C)
Never make a flush cut as shown here. This causes
Monitoring for insects and
Generally, a well-cared-for tree will not succumb
to lethal insect or disease problems. However,
some insects and diseases (such as borers and
hypoxylon canker) can be deadly to trees, especially
if trees are under stress from another problem.
Have a professional arborist or forester check the
trees regularly as part of a preventive maintenance
program to help keep these and other pests from
becoming problems. As with people, the best way
to ensure continued health is with preventive
Construction and trees
Perceptions about tree roots are quite different
from reality. Trees growing in urban areas seldom
develop tap roots. In fact most roots are located
within the top 12 inches of soil because this is
where aeration, nutrients and moisture are abun-
dant. The feeder roots grow just below the surface
of the soil or mulch, or among the lawn and shrub
roots. About 50 percent of the tree root system
grows beyond the canopy, and the tips of the roots
are three times as far from the trunk as the canopy
(Figure 7). Construct a fence around the tree at the
Figure 7. Roots spread to three times the edge of the canopy.
Trees often decline following construction of a
building because a large portion of the roots were
edge of the canopy (dripline) to reduce root damage
Due to the extent and shallowness of the roots,
much of the root system is frequently removed from
existing trees during construction of a home or
other building. This causes decline and tree death
in the years following construction. The best
treatment for trees damaged by construction is
irrigation. Heavy fertilizing may make the problem
worse by forcing undesirable top growth, which
cannot be supported by the reduced root system.
How to hire an arborist
Arborists make a career of caring for trees. Here
are several tips for selecting an arborist:
* Avoid arborists who routinely top trees.
* Have more than one arborist look at the job, and
get a written bid specifying work to be done.
* Ask for and check local references.
* Beware of an arborist who wants to remove a
living tree. Removal of live trees is sometimes
needed, but should be the last resort.
* Determine if the arborist is a member of the
International Society of Arboriculture or the
National Arborist Association. Membership does
not guarantee quality, but lack of membership
casts doubt on the person's professionalism.
* Ask for certification of personal and property
liability insurance and workman's compensation.
Then phone the insurance company to make
certain the policy is current.
* Low price is a poor gauge of a quality arborist.
Often, the better ones are more expensive
because of more specialized equipment, more
professional help and insurance costs.
A Selected List of Trees Suitable for Urban Areas in Florida*
North / Central Florida
Southern Red Oak
Swamp Chestnut Oak
East Palatka Holly
Southern Red Cedar
Canary Island Date
Queen's Crape Myrtle
Chinese Fan Palm
Canary Island Date
*For a more complete list and for more information, contact your local Cooperative Extension Service Office or the
Division of Forestry in your county.
Additional resources available at your local Cooperative Extension Service Office
Landscape Plant Selector CDROM computer program
Landscape Design Selector CDROM computer program
SS-ORH-903 Dispelling misconceptions about trees
Circular 853 Pruning landscape trees and shrubs
SS-ORH-905 Tree training and pruning
SS-SOS-909 Soil pH and landscape plants
Circular 489 A guide to selecting existing vegetation for low energy landscapes
Circular 948 Fertilizer recommendations for trees and shrubs in home and commercial landscapes
SS-ORH-02 Palm nutrition guide
SP 51 Florida insect control guide
SP 52 Florida disease control guide
Circular 922 Florida guide to environmental landscapes
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOODAND AGRICULTURAL SCIENCES, John T. Woeste,
director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30,1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, handicap or national origin. Single copies of extension publications (excluding 4-H and youth publications)
are available free to Florida residents from county extension offices. Information on bulk rates or copies forout-of-state purchasers is available from
C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611. Before publicizing this publication,
editors should contact this address to determine availability. Printed 11/91.