How to prune a tree

Submitted by: Marc Williams
February 17, 2016 9:25 a.m.

I know you have seen them. Pitiful looking palm trees with just a handful of fronds sticking straight up. Oak trees, usually in parking lots, with most of their limbs chopped off leaving a few scraggly branches at the top. Crape myrtles that have been whacked time and again until the trunk is a gnarly mess. These common but harmful practices result in severe detriment to the trees. The “Hurricane Cut” for palms, the “Strip Mall Strip” for oak trees and “Myrtle Murder” for the crape myrtles are three examples of over-pruning that we should be concerned about.

There has been a lot of energy expended in the Amelia Island area lately on saving trees from being taken down. That’s fine because we do need to help preserve as many old-growth trees as possible. But what about treating the remaining trees with respect? It turns out incorrect pruning can severely damage the structural integrity of the tree, potentially causing the tree to become a high risk for limb breakage.

We seem to want to change the shape of Mother Nature to fit our own view, but it’s pretty clear, she knows best.

THE HURRICANE CUT

This phenomenon of cutting off most of the fronds from a palm, leaving a few sticking straight up in the air, is a popular practice by landscapers and homeowners. The proposed theory is that there is less wind resistance with only a few fronds on the tree allowing it to more easily survive high winds. But actually, the opposite is true. Extensive research has been done on this topic and it turns out nature knows best about how to survive a hurricane. Palms were designed to withstand winds and have survived for a long time by themselves. In addition, over-pruning damages a palm by removing important nutrients and causing stress on the palm. In truth, fronds should be left on the tree until they are totally brown. The only time this practice of removing most of the fronds is recommended by the University of Florida occurs when Sabal palms are being transplanted. Otherwise, the fronds should be left on the tree until completely brown.

Doug Caldwell, Ph.D., commercial landscape horticulture extension educator and landscape entomologist with the University of Florida in Collier County Extension, is one of the leading experts on palm maintenance. His advice is, don’t do the hurricane cut:

“Over-pruning palms with the “hurricane cut” weakens them structurally and nutritionally. The green fronds photosynthesize carbohydrates for growth and store nutrients translocated from the roots, potassium being one of the major nutrients. When the green fronds are removed one can see an abrupt, or over the years, gradual narrowing of the trunk. Think of it as going on the Atkins diet. This narrow point in the trunk can, in high winds, create a rocking or pivot point which can cause the heavy head to break.”

Dr. Caldwell has produced a very informative video on proper palm care and you can view it here: https://www.youtube.com/watch?v=Tt76hXRHBoA

That’s not to say palms should never be pruned. Proper maintenance will enhance the look of your palms and landscape. For most palm trees the recommended procedure is to prune only the dead fronds, and at the most, do not trim off any fronds above the 9-3 o’clock profile. Some of our deadliest horticultural diseases have been spread by poor pruning cuts on palms so it is essential to maintain sterile pruning practices.

To get more detail on proper palm maintenance, check out these articles published by the University of Florida:
http://gardeningsolutions.ifas.ufl.edu/giam/plants_and_grasses/trees/hurricanes_palms.html

THE STRIP MALL STRIP

One of the distinctive characteristics of our island area is the large population of oak trees providing pleasing vistas, canopy roads, summer shade, animal habitat, carbon dioxide / oxygen gas exchange, and other ecological benefits. There has been a lot of effort recently to preserve these trees on and off the island, especially the large old-growth specimens. However, these are not the only trees in danger. There is a common pruning practice performed on many landscape trees which not only looks bad, but damages the tree. I call this the “strip mall strip” because it appears most often in shopping and office building areas.

Office park and strip mall owners plant trees and other shrubs in parking lots, ostensibly to improve the look of the premises, making their property more attractive and inviting to customers. Then as the trees mature, store owners may complain their businesses cannot be seen from the road, thereby losing customer traffic. This often results in severe pruning of the offending trees.

It is understandable that proprietors wish to have clear sight vision to their stores, but over-pruning large-bodied trees such as oaks has detrimental effects. Foremost is the damage done to the structure of the tree. When major limbs are cut off, leaving only a few at the top, the tree will loose it ability to gather and distribute nutrients and will eventually die, either due to structural loss or succumb to disease.

The loss of aesthetic value is obvious and the tree’s usefulness is vastly diminished. Oak trees were never meant to be cut like poodles and look ridiculous with just a top notch. But one the most important uses of the tree is lost: shade and reduction of the heat index created by asphalt parking lots. Here in Florida shade is a hot commodity in the summer, especially in parking lots. A nice spreading oak or other shade tree provides an enticing place to park while you shop or transact business. From a business proprietor perspective this may be a greater amenity to customers than a clear sight to the front door.

As a suggestion, consider pruning the offending trees a little at a time, allowing the tree to grow wide as well as tall, perhaps taking 3 – 5 years to develop the structure of the tree.

Eventually the tree will be tall enough to see under, but wide enough to be healthy and offer good shade. Your landscape trees are valuable assets and should be considered in your long range planning. The best practice before pruning is to consult a certified arborist before letting the chainsaw gang loose.

Here is an article with some good information about proper tree pruning:
http://www.arborilogical.com/tree-knowledge-articles-publications/dangers-of-over-pruning/

MYRTLE MURDER

It’s unclear exactly how myrtle murder, or “crape murder” as some horticulturists call it, became so prevalent. Some crape myrtles get whacked down so severely they will never regain their natural form or structure. Some plants get severely pruned because they are the wrong plant in the wrong place and must be tamed. Others are whacked because it is thought to enhance blooming. Others get chopped because neighbors are doing it, so it must be the right thing to do, right? Landscape maintenance crews do it because either the homeowner demands it or they don’t understand the proper procedure either. We all should know better.

Over-pruning not only ruins the structure of a crape myrtle but is aesthetically repellent. Figure 4 shows some old shrubs continuously over-pruned and are now just gnarly stumps. Myrtles are hardy characters and these shrubs will sprout new shoots straight up in the air, but will never again resemble a proper shape and the new growth will not have the appropriate strength. Crape myrtles want to be free and should be allowed to flourish. Proper, controlled pruning can enhance the beauty of these plants and should be done with respect. You can see outstanding examples of properly maintained crape myrtles in many locations, especially in roadway medians that have been cared for by knowledgeable landscapers.

If you wish to plant crape myrtles in a smaller or confined space be aware that there are now cultivars that do not grow to a large size. These dwarf, compact versions will not need to be severely pruned and will develop their natural shape without overtaking a large space.

Here is a link from Clemson University extension service with some great information on proper care:
http://www.clemson.edu/extension/hgic/plants/landscape/trees/hgic1009.html

If you have an interest in becoming better informed about proper tree and shrub maintenance, I highly recommend attending one of the fine programs conducted by Rebecca Jordi, University of Florida Nassau County Extension Director. Ms. Jordi, a certified arborist, is well-known for her deep knowledge of local horticulture and conducts a very entertaining and educational outreach program. Her next landscape pruning class will be February 17 at 10am at the James S. Page Governmental Complex (behind the bread outlet!). The class is free to the public. She has a palm class scheduled at the same site May 25 at 10am. Invite your landscaper to attend as well.

Here is a link to the Nassau County extension service calendar:
http://nassau.ifas.ufl.edu/horticulture/calendarevents.html

My intent in highlighting these issues around tree maintenance is not to criticize anyone. Rather, it is to help raise awareness of some problems we might not even notice with regard to the care of our horticultural environment. Protecting trees from destruction is important. But properly caring for the ones we have is important, too. With proper care and respect of these resources, the natural beauty of Nassau county and Amelia Island will continue to be admired for generations to come.

Many thanks to Rebecca Jordi and Dr. Doug Caldwell for their support and guidance.

Editor’s Note: Marc Williams is a native of central Florida, growing up in Leesburg and then a resident of Georgia for many years. After living part time in Fernandina Beach since 2006 he and his wife, Beverly, moved here permanently in 2012 after retiring from Cisco Systems. Marc is a volunteer in the Florida State Park system and an active member of the European American Business Club of Amelia Island. (EABC). He holds a B.S. of Industrial Electronics from the University of West Florida.