Pruning plays a very important part in the maintenance of strong and healthy urban landscape trees. The need for pruning could be reduced by planting the right tree in the right place. Pruning should begin while the tree is young; this will cut down on the problems that may occur in the future. The removal of heavy limbs or the climbing of large trees should be left for certified arborists.
Reasons to Prune an Urban Landscape Tree
Safety: Removing branches that threaten to fall and cause personal injury or property damage or block sight of traffic on city streets can increase safety. Dangerous branches are dead, diseased or injured. Healthy branches are not dangerous, even if they hang over a house, walkway, etc. Healthy trees are very strong.
Health: Removal of dead, diseased, insect-infested or injured branches should be done as soon as possible. This helps to reduce the chance that disease or infestation will spread. Pruning this wood correctly increases the chance of a safe wound closure. Crossed and rubbing branches should also be removed since they create wounds that are havens for insects and diseases.
Aesthetics: Pruning can be done to enhance the beauty of the tree's natural form. Open-grown trees in the landscape do very little self-pruning. Flower and fruit production can also be enhanced by pruning.
When to Prune
The best time to prune limbs is during the late winter or early spring. This allows maximum wound closure during the growing season and reduction of disease transmittal. Please note that some tree species have a habit of "bleeding" when sap is rising in early spring and pruning would be best performed at another time (i.e. maples).
Dead Branches: Cut the branch just beyond the branch bark ridge and the branch collar (which will continue to grow even after the branch is dead). Cut large branches with the three-step method below, so the limb does not make a large tear in the trunk.
Living Branches: Small limbs can be cut with sharp, bypass-type hand pruners. Support limb with one hand to avoid bark tear. The clean cut should be made just outside of the branch collar.
Large Branches: If a limb is too large to support with your arm, use a pruning saw and make a three-step pruning cut.
- First, make a shallow notch on the underside of the branch.
- Then, make second cut outside of the first cut, leaving a stub.
- Cut the stub just outside of the branch collar.
Basic Rules of Pruning
- Examine trees on a regular basis to determine if they need to be pruned. Proper pruning of leaves at an early age can reduce the need for future maintenance.
- Never remove more than one-third of the live crown of a tree.
- Properly prune dead, dying, diseased and weakly-attached limbs and sprouts.
- Prune V-crotches; leave branches with wide angles. The ideal branch angle should be at two or 10 o'clock.
- Remove multiple leaders and crossed branches.
- Never leave stubs or flush cuts.
- Do not use tree or wound paint.