If you frequent gardening blogs or browse the gardening section of your local bookstore, you’ve likely come across experts criticizing anvil pruners. One common complaint is that their design makes it difficult to cut close to the branch collar without leaving a stub. Another, more pervasive critique is their potential to crush the cambium—especially on softer branches.
In contrast, bypass pruners are lauded for making cleaner cuts, as their blade slices all the way through the stem. When used correctly, they allow for cuts close to a branch union without leaving a stub. Any cambium damaged while pruning is purportedly limited to the portion of the branch being removed.
Given the clear advantages of bypass pruners, why are anvil pruners still being manufactured and widely sold in garden centers and online retailers? Who continues to buy and use them despite their shortcomings and the excessive damage they supposedly inflict on dogwoods and durantas?
A Completely Non-Controversial Perspective on Pruning
When you squeeze a living branch between a sharp blade and a blunt backstop to sever it from its point of origin, you are inflicting physical harm on a plant. Sometimes, this harm is inflicted to enhance the plant’s aesthetics by promoting flowering or creating a desirable shape. Other times, this harm serves a more practical purpose—providing clearance for structures, vehicles, and pedestrians. In cases where extending the longevity of a tree or shrub is the primary concern, this harm may be inflicted to create a more storm-resilient structure or to remove diseased or parasitized tissue.
Regardless of intent, pruning a living branch injures the plant. The severity of this injury can range from nearly inconsequential to significant, depending on factors such as the amount removed, the plant’s overall health, and its species. When live branches are pruned responsibly and with a clear objective, the benefits typically outweigh any negative consequences.
This all noted, an obvious question arises when reading about the damage caused by anvil pruners.
How detrimental are a few millimeters of crushed cambium when it is associated with the removal of a meter’s worth of living plant material?
We weren’t sure, so we decided to find out.
Show Us the Data!
While opinions abound regarding the merits and flaws of the anvil pruner, data is scarce. At Rooted in Tree Research, we recognize the value of professional experience and expertise, but as scientists and extension educators, we are hesitant to pass along anecdotes as fact.
Research on this topic is limited, but we found one paper that compared bypass pruners to anvil pruners when making removal cuts (i.e., cutting a branch back to a larger stem or the trunk). In this study, wound recovery was similar between cuts made with bypass pruners and anvil pruners, despite observing greater levels of injury in cuts made with the former.
Any single study could produce a false positive or negative, which is why repeating studies is an essential part of science. As such, we decided to conduct our own research project assessing how trees responded to being pruned with four brand-new pruners sourced from our local big-box store (two anvil and two bypass pruners). This time, we opted to make reduction cuts (i.e., cutting a branch back to a smaller lateral branch).
Stay tuned for our next post, where we’ll share our study design, the pruners used, and our initial data on injury!
About this Blog
Root in Tree Research is a joint effort by Andrew Koeser and Alyssa Vinson. Andrew is a research and extension professor at the University of Florida Gulf Coast Research and Education Center near Tampa, Florida. Alyssa Vinson is the Urban Forestry Extension Specialist for Hillsborough County, Florida.
The mission of this blog is to highlight new, exciting, and overlooked research findings (tagged Tree Research Journal Club) while also examining many arboricultural and horticultural “truths” that have never been empirically studied—until now (tagged Show Us the Data!).
7
