Heartwood Tree Pruning
Heartwood tree pruning is the dead wood that acts as the structural reinforcement in your tree, much like rebar in a concrete footing. This rigid reinforcement combined with outer sapwood rings gives trees a perfect balance of stiffness and flexibility.
When correctly pruned, a tree is stronger and less likely to fail under stress. Pruning wounds should be closed quickly by the tree in a way that encourages controlled new growth.
Young trees need proper training. This ensures a strong scaffold structure and reduces the need for corrective pruning later on. It can be difficult to shape a tree or shrub into an ideal form, but it is possible and necessary to prune in observance of the plant’s natural growth habit. This can eliminate inward-growing branches, crossing branches, limbs that obstruct traffic or buildings or narrow V-shaped crotches.
When thinning or reducing a branch make sure to cut to the side of what is called the stem collar. This is a lip of bark that each branch protrudes from. Never cut flush with the trunk, this causes more damage and leaves a pocket that can harbor wood-decaying fungus. Also, pruning wounds should be covered by bark. Wounds that are exposed can quickly rot, and small cuts close much faster than large cuts. This is why it is important to always use a clean, sharp tool.
Removing Dead or Damaged Branches
In the case of a dead or diseased branch, it is important to remove it quickly. This will help prevent infection of the tree in general, and in the specific limb that was damaged.
This will also encourage the cambium layer to close over the wound. A dead limb will allow water to stand on the rough edges, which invites unwanted insects and fungus to enter the wound.
Invasive weeds such as English ivy and kudzu can be a major problem and should be removed before they cause significant damage to the tree. During maintenance pruning, the ivy and other vines can be removed from the base of the tree.
The ivy and other vines can also be pulled out, but this is best done with professional help to avoid causing damage to the tree’s roots. If the ivy is allowed to grow up and around a tree, it will begin to take up valuable sunlight and water, leading to stress and eventually death of the tree.
Removing Large Branches
If a plant is growing too large for its site it might require pruning to reduce the size or keep it in bounds. Pruning a tree to form a formal hedge, espalier or topiary is an example of corrective pruning.
When pruning larger branches, be sure to preserve the branch collar (the raised tissue at the base of every branch) and avoid leaving stubs. The ridges and collar contain specialized cells that allow a tree to quickly seal off pruning wounds and prevent wood rot fungi from entering. Also, don’t use wound dressings; there is little evidence they improve tree health.
On new plum and prune trees, select three or four shoots to be scaffold branches the first winter and remove other shoots or severely head them. This promotes branching and helps the tree develop a strong structure. Also, prune to thin out crowded branches after the first 5 or 6 years of growth to prevent limb breakage and promote fruiting.
When trees decay, they release a steady supply of organic fertilizer. The decay organisms that colonize a tree’s core are a natural microbial metabolism that decomposes old growth rings and releases trapped minerals, creating an incredible system of nutrient cycling.
When thinning mature trees, pruning cuts should be made just outside of the branch collar and bark ridge, a swollen area that wraps around the base of a branch union (upper illustration). This keeps the tree’s natural defense mechanisms in place and promotes wound compartmentalization and callus formation. Flush cuts destroy this collar and ridge, leaving open wounds that invite infection.
Clearance pruning removes branches that interfere with power lines and includes reducing the height and/or spread of a canopy by using reduction cuts, while maintaining standard clearance (3 feet from buildings/structures, 8 feet over sidewalks, 14 feet over roadways). We also prune to remove dead or damaged limbs and remove lower sucker growth.