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Master Gardener Scoop: Don’t Stub That Tree

By Linda Summers,

Master Gardener

Driving home from Centralia this week, I noticed the shape of different kinds of trees and how their plant location determines whether they will be allowed to grow and develop into their natural form.  In many instances, the tree was a great lesson in how not to prune or where not to plant a tree.

Although I saw many trees that had lost limbs, it was quite noticeable how many trees had been stubbed or topped.  This article discusses tree pruning in general and offers some suggestions for helping maintain a healthy and beautiful tree.

Pruning can best be explained as the removal or reduction of unwanted plant parts, and it is necessary for a variety of reasons.  We prune trees for safety, health and form/aesthetics reasons, as well as to encourage flowers or fruit.  Pruning may remove dead, diseased, insect-infested or rotting wood.   The tree may have limbs that are crossed or rubbing together that could create wounds or entry points for disease.  In the case of flowering or fruit trees, pruning encourages fruiting by allowing light penetration and encouraging new growth.

Pruning does cause injury to the tree and some species react more positively to pruning than others.  Mature silver maples do not always do well after being pruned.  Removing large limbs on this tree makes it more susceptible to decay and trunk cavities.  Proper pruning done when these trees are younger may avoid later problems.

One practice that seems to be common and seems to be a slow way of killing a tree is tree topping or stubbing.  Topping a tree is usually done when the height of the tree is no longer acceptable, but it is clearly not an acceptable pruning practice.  The stubs frequently decay or die back, and numerous weak shoots may develop at the site of the cut.

My top five pruning tips are:

1.  First of all, look at your landscape design when planting a tree for the first time.  Consider the tree’s natural characteristics, such as shape and height at maturity, as well as its physical requirements before planting.  Don’t plant trees that will overhang the road or grow into utility lines.  Otherwise, the utility company may prune your trees to the detriment of the trees.

2. Young trees are pruned with the idea of developing a strong structural framework early in the life of the tree.  However, avoid heavy pruning when you first plant a tree.  The newly planted tree needs foliage to produce carbohydrates and other plant chemicals necessary for healthy root formation. Trees with wide crotch angles provide a stronger framework than those with narrow crotch angles.  Again, silver maples tend to have narrow crotch angles, making them more susceptible to damage during ice and windstorms.  It is recommended that a tree be pruned seven times in the first 25 years.

3.  Do not cut tree limbs flush with the trunk.  Look for the branch bark ridge, which is the area where the tree develops wound wood (callus tissue) in response to the cut.  Cutting trees flush with the trunk opens the tree to decay and the cut does not heal as well as callus tissue.  For large or heavy limbs, use a three-cut method to avoid the branch ripping downwards and damaging the branch bark ridge or trunk.

4.  Time your pruning.  The absence of leaves makes it far easier to see the branching structure of the tree and which limbs need to be removed.  Pruning when the tree is dormant is usually the best time.  However, heavy pruning of fruit trees during the dormant season produces the same effect as fertilization.  If you heavily prune a fruit tree, reduce or omit fertilization.

5.  Realize that pruning requires experience.  If you have large mature trees, hire an arborist to prune your trees.  If you have small trees, study or take a class in tree pruning to learn proper techniques of pruning before you make a mistake that can have a negative impact on the development and growth of the tree.

There is a substantial amount of information on pruning both trees and shrubs.  For more information, please call or visit your local University of Illinois Extension Office.  Please visit the Master Gardeners/Master Naturalists tables at the Midwest Herb and Garden Show, February 10-12, at Times Square Mall in Mount Vernon.

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