Tree pruning is something you can do to help your trees stay strong, healthy, and attractive, but there’s a lot more to a good pruning job than just lopping off some branches here and there.
This is the first installment of a two-part series on the topic, and this month’s column will focus on the reasons for pruning, and the time of year that is best for pruning.
There are a lot of reasons to prune trees, but most of them fall into the categories of safety, tree health, appearance, fruit production and timber value.
Pruning for safety is important when dead or dying limbs create a hazard for high traffic areas, such as picnic tables, sidewalks, or roads, and also for structures like sheds or houses.
Pruning for tree health can help prevent problems from getting started and treat existing problems.
Many pathogens prefer the moist conditions created by a dense canopy with very little sunlight or air flow. Removing branches helps to keep the interior structure of the tree dry.
Branches that rub together should be cut, as the wounds that result are often sites of infection.
Fungal and bacterial infections that kill trees branch by branch can be slowed down and occasionally stopped by removing infected limbs.
When pruning to control an existing infection, it is extremely important to keep your tools sanitized, so that you don’t do more harm than good by spreading the pathogens to new places.
Remove all wood particles and use 70-percent denatured alcohol to clean all cutting surfaces.
It’s best to let the blades soak in the solution for two minutes. A 10-percent solution of household bleach can also be used, but metal tools should be washed with soap and water when done, as bleach is corrosive.
Trees are often pruned to help them grow in a pleasing shape.
It’s best to complement a tree’s natural shape by removing the branches that don’t fit into the pattern.
Pushing a tree too far away from its natural form is a lot of work and can damage or kill it.
Fruit trees’ tops can be pruned to keep the fruit within reach for easy picking.
Removing excessive vegetative growth can also help to concentrate the trees resources on fruit quality and quantity.
Although pruning for timber value is not often practiced in Delmarva, it is a common practice in other parts of the country and the world, especially in intensively managed pine plantations.
Here’s how it works: Each branch of a tree creates a knot in the tree trunk.
Because the tree adds another layer of wood around the branch every year, this knot starts in the center of the tree and extends to the branch itself.
But if that branch is pruned when the tree is 10 years old, that knot will only go from the center of the log to the 10th ring.
In a 40-year-old tree, the knot would only show up in a small portion of the wood from that log.
These knots are one type of defect that reduces the value of a log when it’s purchased for lumber or veneer.
Pruning the bottom 10 to 18 feet of a tree when it’s young keeps those knots small and limited to the core of the log.
A butt log with mostly clear wood can be worth much more than a similar log of the same size and shape that has lots of knots.
This doesn’t necessarily mean that you should start hacking away at your pine trees, though.
The time and money you invest in pruning may or may not pay off when the trees are harvested.
This depends on the market conditions at the time of harvest, site conditions, and other characteristics of the tree.
Talk to a professional forester before starting any big projects.
The timing of your pruning is important.
Pruning should be done during the winter in most cases.
The tree will lose less sap, will have an entire season to grow over the wound, and will be less likely to attract pests.
It’s also easier to see the structure of the tree when the branches are bare.
Trees with showy flowers in early spring, like dogwoods and redbuds, can be pruned immediately after flowering, so that you can enjoy the flowers that were developed in their buds during the previous year.
Next month’s installment will focus on pruning tools and techniques.
More information can be found at bit.ly/treepruning.
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