Myth 7: If certain species of trees are pruned early in the
spring, they will "bleed," stressing the tree and causing health
problems. True, some trees such as maples and birches will
"bleed" or lose sap from pruning cuts made early in the spring. This
bleeding does not hurt the tree, and the loss of sap is
inconsequential. With a few exceptions, most routine pruning can be
done anytime of year. The worst time is just as the tree has leafed
out in the spring. The best time is when the tree is dormant. To
maximize flowering for the following year, prune just after bloom
Myth 8: The root system of a tree is a mirror image of the top.
Many people envision a large, branching taproot growing deep
into the soil. Actually, taproots are very uncommon in mature trees.
If taproots do develop, they usually will be forced into horizontal
growth when they encounter hard subsoils beneath the surface. The
entire root systems of most trees can be found within 3 feet of
soil. The spread of the root system however, can be very extensive,
often extending two to three times the spread of the crown.
Myth 9: Trees require "deep root fertilization" to reach their
root system. In most U.S. soils, the vast majority of trees'
fibrous, absorbing roots are in the top 8 inches of soil. Roots grow
where conditions are best for root growth, where water and oxygen
are available. When fertilizer is placed 12 to 18 inches deep in the
soil, it is too deep.
Myth 10: When a tree has lost a significant portion of its root
system, such as in construction damage, the crown should be cut back
to compensate for root loss. While this is a common
recommendation, research has not supported it. Following root loss,
unpruned trees seem to respond better than pruned trees. Obviously,
any removal of branches will reduce the capacity of the tree to
produce food in the leaves. Although the tree will probably lose
some branches as a result of the root damage (if the tree survives
the trauma), it is best to let the tree decide which ones. Thus,
pruning should be limited to hazard reduction at first. Later, after
the tree has responded to the damage, further pruning would be in
Get advice from an arborist. An arborist is a professional in
the care of trees. A qualified arborist can give you sound advice
and can provide the services your trees may need. Good arborists
will perform only accepted practices. When choosing an arborist,
look for certification by the International Society of
Arboriculture, membership in professional associations, and ask for
proof of insurance. Be weary of individuals who go door-to-door
offering bargains for doing tree work. Don't be afraid to check
Be an informed consumer. One of the best ways to be assured
you are making wise decisions regarding your trees is to educate
yourself on some of the basic principles of tree care. The
International Society of Arboriculture offers a number of brochures
designed to inform consumers about trees. For a free set, write to
ISA at P.O. Box 3129, Champaign, IL 61826.
The International Society of Arboriculture is a nonprofit
organization supporting tree care research around the world.
Headquartered in Champaign, the society is dedicated to the care and
preservation of shade and ornamental trees. For more information,
contact a local ISA-certified arborist or visit
[International Society of
Arboriculture news release]