Help Trees Take Shape: Prune Properly
For Immediate Release
For Further Information Contact Sonia Garth:
(217) 355-9411 Ext 217
Help Trees Take Shape: Prune Properly
CHAMPAIGN, IL- In search of a strong structure and a
desirable form … for your tree? If so, prune your trees when they are
young. This will result in less need for corrective pruning as they mature. In fact, with a basic understanding of tree biology, homeowners can properly
prune young trees, maintain tree health and structure, and enhance the aesthetic
and economic values of their landscape, said Jim Skiera, Executive
Director of the International Society of Arboriculture (ISA).
Why do people prune trees?
People commonly prune trees to remove dead branches, remove crowded or
rubbing limbs, or to eliminate hazards. Trees also are pruned to increase light
and air penetration to the inside of the tree’s crown or to surrounding
landscape. But in most cases, mature trees are pruned as a corrective or
preventative measure. Since each cut has the potential to change the growth of
the tree, no branch should be removed without a reason, Skiera said.
"Urban environments are not ‘natural’ conditions for trees, so trees usually
have to be modified in some way," Skiera said. "But homeowners need to remember
that heavy pruning can severely stress a tree. They need to exercise caution and
a little common sense when they prune."
Removing foliage - the primary source of energy-producing sugar for trees -
can reduce growth and stored energy reserves. Skiera said a good rule of thumb
for pruning is to maintain at least half the foliage on branches in the lower
two-thirds of a tree.
Pruning techniques
There are specific types of pruning that help trees stay healthy, safe, and
beautiful.
-- Cleaning removes dead, dying, diseased, crowded, weakly attached,
and low-vigor branches from the crown of a tree.
-- Thinning selectively removes branches to increase light penetration
and air movement through the crown and reduces weight on heavy limbs to retain
the tree’s natural shape.
-- Raising removes lower branches from a tree to clear space for
buildings, vehicles, pedestrians, and views.
-- Reduction trims the height or spread of a tree by pruning back the
leaders and branch terminals to lateral branches that are large enough to assume
the terminal roles (at least one-third the diameter of the cut stem). Compared
to topping, this helps maintain the form and structural integrity of the
tree.
When to prune
Most routine pruning to remove weak, diseased, or dead limbs can be done at
any time of the year. But growth is maximized and wound closure is fastest if
pruning occurs before the spring growth flush - when trees have just expended a
great deal of energy to produce foliage and early shoot growth. Heavy pruning
immediately after growth flush can stress the tree. Avoid pruning during active
disease transmission periods. A few tree diseases, such as oak wilt, can be
spread when pruning wounds allow spores to access a tree.
Proper pruning cuts
A pruning cut’s location is critical to a tree’s response in growth and wound
closure. Pruning cuts should be made just outside the branch collar, which
contains trunk or parent branch tissue that should not be damaged or removed.
When removing a large limb, first reduce its weight to avoid tearing the
bark make an undercut about 12-18 inches from the limb’s point of attachment.
Then make a second cut from the top, directly above or a few inches further out
on the limb.
How much to prune
The amount to remove depends on the tree size, species, and age, as well as
pruning objectives. Younger trees can tolerate more pruning than mature trees.
Skiera says: "A tree can recover faster from several small pruning wounds than
from one large wound." Removing just one, large-diameter limb can create a wound
that the tree may not be able to close. The older and larger the tree, the less
energy it has to close wounds and ward off decay or insects.
Hiring an arborist
Pruning large trees can be dangerous - it usually involves working above the
ground and using power equipment. Ensure your safety, and that of your trees, by
hiring a professional arborist.
The International Society of Arboriculture (ISA), headquartered in Champaign, IL, is a nonprofit organization supporting
tree care research around the world. As part of ISA's dedication to the care and
preservation of shade and ornamental trees, it offers the only internationally-recognized certification program in the industry. For more information, contact a local ISA Certified Arborist
or visit
www.isa-arbor.com.