Pruning Trees (Part 2 of 2)

How to Prune

Before you begin pruning assess the entire tree. Come up with a comprehensive plan and ultimate goal of what you are trying to accomplish. Make good pruning cuts. When you prune a tree you are creating a wound. Trees don't heal like people do; they do not regenerate tissue. Rather, trees callus over wounds or compartmentalize to seal off decay. The wound will forever be a part of the tree. Keeping that in mind, it is important to minimize the damage made from a pruning cut.

• Once a branch has been chosen for removal, identify the branch collar or bulge near the base of the branch (below).

• The branch collar contains active tissues that help in the healing process. It is important not to damage this part of the tree when making your cut.
• When making the cut, try to keep your hand pruners or saw just on the outside of the branch collar.
• If you cut into the branch collar it is called a "flush cut" and should be avoided

• If you cut too far out from the branch collar you are likely to leave a stub. The tree will have a hard time healing over a stub leaving it vulnerable to diseases and harmful bacteria.

• Here is an example of a proper pruning cut made just on the outside of the branch collar but not too far out on the branch so as not to leave a stub.

• Establish a central leader. Establishing a central leader will encourage upward growth of the tree. It will also create better structure and aesthetics as well as long term health and safety.
• The tree in the photo below left has co-dominant leaders, or two competing leaders. If left alone this may create future problems, as shown on right

• The photos below are showing how one leader can be removed. Try to keep the main stem or the branch with higher growth rate and remove the other one.

• If the branch is too large to cut with a hand pruners then use the 1-2-3 cut method to avoid tearing the bark as the branch separates from the tree.

 

 

o   Cut 1: Saw into the underside of the branch. Be sure to score the entire lower side of the branch.

o   Cut 2: Saw off the weight of the branch a few inches out from the first cut.

o   Cut 3: Remove the stub on the outside of the branch collar.

Rules to Remember

• If the pruning requires a chainsaw and ladder then call a professional arborist
• Never prune more than 25% of the tree's canopy at one time
• NEVER top a tree (shown below left). It is harmful and creates a dangerous tree
• Don't "lion's tail" or over thin the crown (shown below right)
• Do not tip the branches (cut off the ends of the branches)
• Be sure that you use sharp and sanitized pruning equipment. Dirty equipment can spread disease.  

 

 

To help you determine when and why you should prune your trees, see Part 1 of this series.

Pruning Trees (part 1 of 2)

Pruning is an essential part of caring for urban trees. In nature, trees self-prune in response to different environmental influences. In a yard or boulevard, trees may require help from humans to be good tree citizens in a people-dominated world. Formative pruning on young trees can help them grow to be strong and beautiful. Pruning on larger trees can improve the safety and health of the tree. Keep in mind that improper pruning is detrimental to the overall health and vigor of a tree. Before you prune be sure you are educated and informed on the proper methods of pruning and always consult a professional if you are unsure.

Reasons to Prune

There are several reasons why it may be necessary to prune your tree. Here are a few of them:

• To remove broken or damaged branches
• To remove diseased limbs or limbs infested with pests, fungus or bacteria that may affect the overall health of the tree
• To train a central leader
• To thin the crown of a tree to allow for air movement
• To raise the crown of a tree to allow clearance from sidewalks or streets

When to Prune

• Newly planted trees should not be pruned within the first two growing seasons except to remove dead or damaged branches
• Coniferous trees may be pruned any time of year, but sap flow will be minimized during the dormant season
• Non-flowering deciduous (shade) trees should be pruned when they are dormant (winter in Minnesota)
• Early spring bloomers (redbud, magnolia and others) should be pruned immediately following flowering in the spring to maximize their blooming capacity
• Crabapples, apples, plums and other fruit trees should be pruned in the dormant season just after the coldest weather has passed
• Dead or broken branches can be removed at any time of year

Check in with us on Thursday, Jan 31 to learn how to prune.

Read Part 2 here.