By Enrique Arayata
February 4th, 2025
Tree pruning is the selective removal of branches, buds, and roots from a tree. Pruning is a common and necessary form of tree maintenance that can be beneficial or detrimental to a tree’s health depending on the location and quantity of the cuts. Poor pruning practices will decrease the health and vigor of a tree and increase the likelihood of structural failure or even worse, tree death. More specifically, improper tree pruning can lead to unaesthetic appearances, stunted growth, insect and disease susceptibility, compromised structure, poor branching habits, decayed and damaged limbs, and property damage due to limb failure. On the flip side, proper pruning practices can increase a tree’s aesthetics, health, and longevity, allowing it to be a beautiful sight for sore eyes instead of a headache for the owner.
The goal for this ARBOR ED™ article is to learn more about improper pruning practices, some of which are contextual and situational depending on the timing, quantity, or location of the pruning cut, and to have you identify if your tree has been improperly pruned! To learn more about the benefits and use cases of tree pruning, read here for my previous ARBOR ED™ article on the importance of tree pruning!
An example of tree topping.
1. TREE PRUNING
One of the most harmful pruning mistakes is tree topping. Tree topping is the removal of entire top-ends of tree stems, sometimes including the central leader, regardless of the stem’s health. Often times, healthy stems with plenty of green leaves are removed during tree topping. The thought behind this is to increase light visibility for grass or plants below the tree, to control a tree’s size, and/or to shape a tree to the owner’s liking. However, tree topping can have serious long-term consequences. Tree topping looks aesthetically unpleasing due to many leaves and greenery being removed from the tree. When topping a mature tree, the topped stem could be large enough to where it is difficult for the tree to properly compartmentalize and close the wound, which is basically an open-door invitation for insect and disease issues. Compartmentalization in layman’s terms is how a tree heals, closes, and recovers from a wound. When large branches are removed, trees will respond by growing small, skinny shoots known as watersprouts that are poorly attached to the trunk. These shoots often grow on the interior of a tree in an upright behavior. They are often weakly attached to the tree and are prone to breakage if they mature large enough. This poses a structural, safety risk for nearby items like concrete, houses, cars, and more. With the removal of much of the tree's canopy, this will reduce its ability to photosynthesize and produce energy. The tree may experience severe stress, making the tree more prone to insect and disease issues.
An example of lion tailing.
2. LION TAILING
Lion tailing is the removal of a majority of the interior or lower branches of a tree stem or an entire tree. This leaves foliage clustered at a branch’s end, similar to the appearance of a lion’s tail. Lion tailing often occurs due to improper pruning practices like tree thinning and general over pruning. This type of tree pruning can often result in weakened branch structure or load failure, causing the limb to break. Two additional consequences of lion tailing are the production of watersprouts and an increased risk of sunburned bark tissue. Lastly, lion tailed trees have less leaves for photosynthesis and will often result in general stress due to a nutrient deficiency.
A subtle example of excessive pruning. Note the small amount of interior branches that is uncharacteristic of honeylocust trees.
3. EXCESSIVE PRUNING
Another common tree care mistake is excessive tree pruning, which occurs when too many branches are removed in one session, or when a tree is over-pruned over a small range of time. While it might seem like pruning a tree heavily will promote its health, in reality, it often does more harm than good. Pruning removes leaves, and leaves are the primary site for photosynthesis. Without enough leaves, a tree struggles to produce the energy it needs to thrive. This leaves it more susceptible to pests, diseases, and environmental stresses like sun scorch and drought. Over-pruned trees are often stunted in growth and will develop the same watersprouts mentioned earlier. The exact amount of pruning for a tree is often debated because there is no definitive answer. The general rule of thumb is to identify the purpose of pruning a tree and to prune as little as necessary to achieve the desired outcome. Common reasons to prune a tree are to reduce risk, improve or restore structure, provide clearance, manage crown size, or to remove dead or diseased limbs. If the reason for pruning can be accomplished with just a few pruning cuts, then there is no need to over prune.
4. INCORRECT PRUNING CUTS AND LOCATIONS
There are many ways that a specific, individual pruning cut can be incorrect and harmful to a tree, so much so that a short book could be written. As a brief, condensed overview, a cut can be improper if it is at an unideal location on a stem or if it was performed using an improper tool. Using a dull or rusty tool can lead to improper cuts that the tree cannot compartmentalize properly. A proper, finished cut should have a smooth surface without jagged edges or torn bark. These defects could create a vulnerable location for insect or disease problems.
Choosing the right pruning tool is important. Most folks would not use a chainsaw to prune a bonsai tree. Trust me, I’ve tried, and it didn’t work out well (for me or the bonsai tree). Jokes aside, there are often gray areas where limbs could be pruned with smaller tools such as loppers or pruning shears, but a handsaw or chainsaw would be more effective and leave a cleaner cut.
Even if a clean pruning cut has been made, it could be at the wrong location and cause increased compartmentalization time, leaving the tree exposed to potential insect or disease problems for a longer period of time. A pruning cut should be made just outside the branch bark ridge and branch collar. The branch collar is the swollen area around the underside/base of a tree branch where it meets the trunk of a tree. The branch bark ridge is a raised strip of bark above a branch union that forms as a result of the trunk and stem connecting, thus pushing the bark into a ridge. Together, the branch bark ridge and branch collar have special tissues that assist in a tree’s compartmentalization response to a pruning wound and to defend that wound from infection. It is important not to damage either of these when making a pruning cut.
5. INSECT AND DISEASE PROBLEMS
Pruning is an excellent maintenance technique to minimize the risk of insect and disease problems for a tree. If you just have a couple of small limbs with decay or unwanted insect pests, they can simply be pruned off. When it comes to an entire tree suffering from a disease or infested with a pest, it is best to have it inspected by an ISA Certified Arborist® to determine the best course of action. Timing is important when it comes to preventing disease and insect pests. There are many tree species with known pest or disease issues that can be minimized through proper pruning at a certain time of year. Two important examples in central Ohio are the pruning of oak and elm trees between October 15th and March 31st to minimize the risk of oak wilt and Dutch elm disease.
6. UNIDEAL TIMING
Timing, both frequency and time of year, are important when it comes to tree pruning. Pruning at an improper time of the year can result in stress and stunted growth. A good, general rule of thumb to maximize growth is to prune a tree just before buds begin to swell, typically around late winter/early spring. Oppositely, pruning a tree around late spring or early summer could cause a tree to grow a little slower, which could be beneficial in an urban or tightly spaced setting. Some trees in temperate settings are best pruned during the active growing season in the middle of spring and summer to maximize the speed of wound closure. Pruning during drought-like conditions such as an unusually hot and dry August should be minimized as a tree is less likely to compartmentalize the wound quickly, potentially leading to decay. An ISA Certified Arborist® working in their local area will be familiar with common, native trees and their preferred pruning window.
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Proper tree pruning is a delicate balance between art and science. While pruning may be done to improve a tree’s aesthetics, it is important to prioritize its health over its looks as a dead tree is an unaesthetic tree. If possible, avoid any and all of the improper pruning mistakes mentioned in this article such as tree topping, lion tailing, excessive pruning, improper cuts, and incorrect timing to ensure that your trees remain healthy and beautiful! As always, if you’re interested in a free tree work quote from one of our 20+ ISA Certified Arborists®, give us a call at (614) 895-7000 or visit RussellTreeExperts.com/Quote!
ADDITIONAL ARBOR ED ARTICLES!
Enrique Arayata I Media Production Manager, Russell Tree Experts
In his free time, Enrique enjoys working out, hanging out with his girlfriend, video production and photography, cars, technology, cooking, and watching new movies and YouTube videos. He has a BA in moving image production with a double minor in film studies and studio art specializing in photography from The Ohio State University, an AA in web graphic design from DeVry University, and is an FAA Certified Remote Pilot.