- Think of tree care as an investment.
A healthy tree increases in value with age--paying big dividends, increasing
property values, beautifying our surroundings, purifying our air, saving
energy by providing cooling shade from summer's heat and protection from
- Providing a preventive care program for your landscape plants is like
putting money in the bank. Regular maintenance, designed to promote plant
health and vigor, ensures their value will continue to grow. Preventing a
problem is much less costly and time-consuming than curing one once it has
developed. An effective maintenance program, including regular inspections and
the necessary follow-up care of mulching, fertilizing, and pruning, can detect
problems and correct them before they become damaging or fatal. Considering
many tree species can live as long as 200-300 years, including these practices
when caring for your home landscape is an investment that will offer enjoyment
and value for generations.
- Tree inspection is an evaluation tool to call attention to any change in
the tree's health before the problem becomes too serious. By providing
regular inspections of mature trees (at least once a year), you can prevent or
reduce the severity of future disease, insect and environmental problems.
During the inspection, be sure to examine four characteristics of tree vigor:
new leaves or buds, leaf size, twig growth, and absence of crown dieback
(gradual death of the upper part of the tree).
A reduction in the extension of shoots (new growing parts), such as buds or
new leaves, is a fairly reliable cue that the tree's health has recently
changed. To evaluate this, compare the growth of the shoots over the past
three years. Determine if there is a reduction in the tree's typical growth
Further signs of poor tree health are trunk decay and/or crown dieback.
These symptoms often indicate problems that began several years before. Loose
bark or deformed growths, such as trunk conks (mushrooms), are common signs of
Any abnormalities found during these inspections, including insect activity
and spotted, deformed, discolored or dead leaves and twigs, should be noted
and watched closely. If you are uncertain as to what should be done, report
your findings to your local ISA Certified Arborist or other tree care
professional for advice on possible treatment.
- Mulching can reduce environmental stress by providing trees with a stable
root environment that is cooler and contains more moisture than the
surrounding soil. Mulch can also prevent mechanical damage by keeping machines
such as lawnmowers and weedwhips away from the tree's base. Further, mulch
reduces competition from surrounding weeds and turf.
To be most
effective in all of these functions, mulch should be placed two to four inches
deep and cover the entire root system, which may be as far as two to three times
the diameter of the branch spread of the tree. If the area and activities
happening around the tree do not permit the entire area to be mulched, it is
recommended that you mulch as much of the area under the drip line of the tree
as possible (refer to diagram). When placing mulch, care should be taken not to
cover the actual trunk of the tree. This mulch-free area, one to two inches wide
at the base, is sufficent to avoid moist bark conditions and prevent trunk
An organic mulch layer of two to four inches of loosely packed shredded
leaves, pine straw, peat moss, or composted wood chips is adequate. Plastic
should not be used because it interferes with the exchange of gases between soil
and air, which inhibits root growth. Thicker mulch layers, five to six inches or
greater, may also inhibit gas exchange.
- Fertilization is another important aspect of mature tree care. Trees
require certain nutrients (essential elements) to function and grow. Urban
landscape trees are often growing in soils that do not contain sufficient
available nutrients for satisfactory growth and development. In these
situations it may be necessary to fertilize to improve plant vigor.
Fertilizing a tree can increase growth, reduce susceptibility to certain
diseases and pests, and can even help reverse declining health. However, if
fertilizer is not applied wisely, it may not benefit the tree at all, and may
even adversely affect the tree. Mature trees making satisfactory growth may
not require fertilization. When considering supplemental fertilizer, it is
important to know what nutrients are needed, and when and how it should be
Soil conditions, especially pH and organic matter content, vary greatly,
making the proper selection and use of fertilizer a somewhat complex process.
When dealing with a mature tree that provides considerable benefit and value
to your landscape, it is worth the time and investment to have the soil tested
for nutrient content. Most quality garden centers can arrange to have your
soil tested at a soil testing laboratory. With the test results in hand, you
can consult your local garden center staff, ISA Certified Arborist or a plant
care professional for advice on application rates, timing, and the best blend
of fertilizer for each of your trees and other landscape plants.
Mature trees have expansive root systems that extend from two to three
times the size of the leaf canopy. A major portion of actively growing roots
are located outside the tree's drip line. It is important to understand this
when applying fertilizer to your trees as well as your turf. Many lawn
fertilizers contain weed and feed formulations that may be harmful to your
trees. When you apply a broadleaf herbicide to your turf, remember, tree roots
co-exist with turf roots. The same herbicide that kills broadleaf weeds in
your lawn is picked up by tree roots and can harm or kill your broadleaf trees
if applied incorrectly. Understanding the actual size and extent of a tree's
root system, before you fertilize, is necessary to determine how much, what
type, and where to best apply fertilizer.
- Pruning is the most common tree maintenance procedure next to watering.
Pruning is often desirable or necessary to remove dead, diseased, or insect
infested branches, improve tree structure, enhance vigor, or maintain safety.
Since each cut has the potential to change the growth of (or cause damage to)
a tree, no branch should be removed without a reason.
Removing foliage from a tree has two distinct effects on its growth.
Removing leaves reduces photosynthesis and may reduce overall growth. This is
why pruning should always be performed sparingly. Over-pruning is extremely
harmful because without enough leaves, a tree cannot gather and process enough
sunlight to survive. However, after pruning, the growth that does occur takes
place on fewer shoots, so they tend to grow longer than they would without
pruning. Understanding how the tree responds to pruning should assist you when
selecting branches for removal.
Pruning mature trees may require special equipment, training, and
experience. If the pruning work requires climbing, the use of a chain or hand
saw, or the removal of large limbs, the use of personal safety equipment, such
as protective eye wear and hearing protection, is a must. Arborists can
provide a variety of services to assist in performing the job safely and
reducing risk of personal injury and damage to your property. They also are
able to determine what type of pruning is necessary to maintain or improve the
health, appearance and safety of your trees.
- Although tree removal is a last resort, there are circumstances when it is
necessary. An arborist can help decide whether or not a tree should be
removed. Professionally trained arborists have the skills and equipment to
safely and efficiently remove trees. Removal is recommended when a tree:
maintenance, trees are attractive and can add considerable value to your
property. Poorly maintained trees, on the other hand, can be a significant
liability. Pruning or removing trees, especially large trees, can be dangerous
work. It should only be performed by those trained and equipped to work safely
in trees. For more information on mature tree care, contact your local ISA
Certified Arborist, garden center, county extension agent or city arborist.
- is dead, dying, or considered irreparably hazardous.
- is causing an obstruction, or is crowding and causing harm to other
trees and the situation is impossible to correct through pruning.
- is to be replaced by a more suitable specimen.
- should be removed to allow for construction.
The PHC Alternative
- Maintaining mature landscapes is a complicated undertaking. You may wish
to consider a professional Plant Health Care (PHC) maintenance program
which is now available from many landscape care companies. Their program is
designed to maintain plant vigor and should initially include inspections to
detect and treat any existing problems which could be damaging or fatal.
Thereafter, regular inspections and preventive maintenance will ensure plant
health and beauty. Refer to our Plant Health Care brochure for more
- This brochure is one in a series published by the
International Society of Arboriculture as part of its Consumer Information
Program. You may have additional interest in the following titles currently in
the series: Insect and
Disease Problems; Mature Tree
Care; New Tree
Planting; Trees and
Turf; Benefits of
Selection; Plant Health
Care; Avoiding Tree
and Utility Conflicts; Recognizing
Tree Hazards; Why Hire an
High-Quality Trees; Tree
Values; Pruning Young
Mature Trees; Why Topping
Hurts Trees; Pruning Young
Mature Trees; Avoiding
Tree Damage During Construction; Treatment of
Trees Damaged by Construction.
Developed by the International Society of Arboriculture (ISA), a non-profit
organization supporting tree care research around the world and dedicated to
the care and preservation of shade and ornamental trees. For further
information, contact: ISA, P.O. Box 3129, Champaign, IL 61826-3129, USA.
© 1995 International Society
UPDATED FEBRUARY 2000