Topping: what extension services and tree bodies say about it
Topping is a pruning practice that each source named here describes as harmful to trees. This page reports what the International Society of Arboriculture, three US universities and PlantAmnesty say about what it is, what it does to a tree, and what they name as the alternatives.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what the named codes, regulators and makers say. It is not training and does not teach the work. The bodies quoted here are publishers of tree-owner leaflets and extension fact sheets, not standards, and none of them is the law. The pruning terms as the A300, BS 3998 and AS 4373 standards use them are on the pruning standards guide. The courses that teach pruning are on the chainsaw tickets guide, the certifications guide and the UK aerial tree pruning award page.
What the sources call topping
The ISA brochure "Why Topping Hurts Trees" (version of February 2021) defines topping as cutting branches back to stubs, or to side branches too small to take over the leader role, without discrimination between cuts. It lists other names: heading, tipping, hat-racking and rounding over. It calls topping "perhaps the most harmful tree pruning practice known".
The University of Kentucky plant pathology fact sheet PPFS-OR-W-32 (April 2023) describes topping as the drastic removal or cutting back of large branches in mature trees, with the tree pruned much as a hedge is sheared and large branches left as stubs. It lists the names heading, stubbing and dehorning. The Iowa State University extension sheet SUL-7 (January 1999) uses nearly the same words and adds that the cut is made with little regard for the location of the pruning cut.
Why the sources say it harms a tree
- Food supply. The ISA brochure says topping can remove 50 to 100 percent of a tree's leaf-bearing crown. Iowa State says that with so much leaf surface gone, the energy-making potential of the tree is severely reduced, and the large stored reserves in stems and branches are lost too.
- Sunburn. ISA says the remaining branches and trunk are suddenly exposed to high levels of light and heat, and Iowa State says bark suddenly exposed to the sun after topping is often damaged by sunscald. ISA lists cankers, bark splitting and death of some branches as results. Kentucky names sunscald and the death of the newly exposed outer bark.
- Decay. ISA says correct cuts are made just beyond the branch collar, which the tree is equipped to close, while cuts between lateral branches leave stubs that the tree may not close. Kentucky says a stub dies and becomes an entry point for insects and wood decay fungi, and that decay can spread from the stub into the main trunk. Iowa State says coating large stubs with a wound dressing is ineffective in stopping decay organisms. The wound dressing guide covers that point.
- Regrowth. All three say the tree answers with a flush of shoots just below each cut. ISA says these shoots grow from buds near the surface of the old branch, are anchored only in its outer layers, and can put on 20 feet (6 m) of growth in a single year in some species. Iowa State calls them weakly attached, Kentucky calls them weak and prone to breakage, and both say topped trees are more likely to be damaged by wind and ice. Kentucky says a topped tree will often be back at its original height within a year or two, which it calls at best a temporary fix for an oversized tree.
- Species that do not sprout. Kentucky names sugar maple, oak and beech as species that do not readily produce shoots after topping, and says the bare trunk that results makes no food and the tree eventually dies. Iowa State names certain beech, maple and oak the same way.
- Risk. ISA says topping is not a viable method of height reduction and may increase risk in the long term. PlantAmnesty, a Seattle non-profit, says on its pruning education page that topping creates hazard trees with weakly attached water shoots likely to break in a wind storm.
Topping next to reduction, as the sources set them out
| Term | What the source says it is | Source |
|---|---|---|
| Topping | Cutting branches to stubs, or to laterals too small to take over as the leader | ISA brochure, February 2021 |
| Reduction | Pruning back leaders and branch ends to secondary branches large enough to take over, at least one-third the diameter of the cut stem; compared with topping it keeps form and structural integrity | ISA, Pruning Your Trees page |
| Reduction cut | Shortens a limb to a lateral at least one-third the diameter of the stem removed; Penn State gives a 3 inch branch cut back to a side branch of at least 1 inch | Penn State Extension, Pruning Landscape Trees, November 5, 2021 |
| Crown reduction | Preferred over topping because the result looks more natural and the weak shoots grow less; still leaves large wounds that may lead to decay in major branches | Iowa State, SUL-7 |
| Thinning | Removing selected branches back to lower laterals; Kentucky says it can reduce height and spread while keeping the natural shape, even under utility lines | University of Kentucky, PPFS-OR-W-32 |
Penn State adds one limit to the word. Its sheet says topping becomes appropriate only when a tree is being removed by shortening sections of limbs as it comes down. It also says several reasons count against topping, among them the loss of food production and the dense, weakly attached shoots that follow.
The alternatives the sources name
ISA names three: removing small branches back to their point of origin, pruning a larger limb back to a lateral at least one-third its diameter, and removing the tree and replacing it with a more suitable species. Kentucky names selective pruning, training trees while young, and removal and replacement where a tree has root damage or is too large for the space. Iowa State says that if a large tree must be topped because it was badly placed, removal is the more practical answer, and that large-growing trees are better kept out from under power lines. Penn State recommends multiple small reduction and removal cuts over time rather than tipping branches or shortening treetops. Where a pruning bid uses the words "topping" or "rounding over", the Penn State sheet says to consider another firm.
For trees under power lines, Penn State describes directional pruning by utilities as the alternative to topping. The rules for line clearance work are on the utility line clearance guide.
Sources
- ISA, Why Topping Hurts Trees brochure, February 2021, read October 9, 2026
- ISA Trees Are Good, Pruning Your Trees page, read October 9, 2026
- University of Kentucky Cooperative Extension, Topping is Hazardous to Tree Health (PPFS-OR-W-32), April 2023, read October 9, 2026
- Iowa State University Extension, Topping: Tree Care or Tree Abuse (SUL-7), January 1999, read October 9, 2026
- Penn State Extension, Pruning Landscape Trees, November 5, 2021, read October 9, 2026
- PlantAmnesty, Pruning education page, read October 9, 2026