In the daily work of Extension, we often make recommendations to our community based on the best available research, but in lieu of a wealth of research on what can we rely? Often, our recommendations follow common practice or industry standards and we strive to shy away from anecdotal recommendations or ‘my uncle always said’ type of advice. As we discussed in our previous blog we want to better understand the challenging conundrum of whether to use bypass or anvil hand pruners for small diameter pruning cuts. Unfortunately, there is a relative lack of substantial research on the long term effects of the various pruners for plant health, so we decided to add our own small study to the existing research in hopes to clarify and offer the best recommendations.
What we did:
Hypothesis (All good science starts with a hypothesis! This is an example of a null hypothesis): The type of hand pruner, Anvil or Bypass, does not significantly affect presence or number of resprouts or the growth of callous wood.
While the study is still in its early stages, the initial results are in, and they’re revealing some interesting insights. So far, it looks like the type of damage caused by the pruners varies depending on the pruner type, but overall, there’s no major difference in how much damage occurs.
What’s Happening in the Study?
The study started with 60 pruning cuts made on trees. Each tree was randomly assigned to one of four groups, depending on the type and size of the pruner used:
- Group 1: Anvil Big Pruners
- Group 2: Anvil Small Pruners
- Group 3: Bypass Big Pruners
- Group 4: Bypass Small Pruners
All branches were about half an inch thick to keep things consistent, and all the pruning was done by the same person at the same time of day. To ensure sizes were similar, we notched up a few small measurement tools using what was lying around the lab. (Research is full of ingenuity and occasionally making due with what you have on hand. Similar to how you might size a crab or lobster claw, the simple gauge was cut to half inch to allow us to slot it onto the branch for sizing.)
What We’re Tracking
Keeping track of which branches were trimmed was an art all on it’s own.
We divvied up the tasks into identify, measure, tag and mark with a high visibility paint pen. Even with all of that, we still needed a map to find the tags when we came back for pruning! The maps, while crude, gave a scaled reference for where to find the numbered tags on a given tree.
Here are the things we’ve been measuring to see how the different pruners affect tree recovery:
- Damage to the Tree: Right after pruning, we looked at whether the branch was damaged, specifically whether the cambium layer (the tissue that helps the tree heal) was crushed or torn.
- Discoloration: In a couple of weeks, we will check the cut ends of the branches to see how much discoloration appeared. We will rate it on a scale from 0 (no discoloration) to 3 (severe discoloration).
- New Sprouts: We will watch for new sprouts that might emerge from the pruning site. We will record whether they appeared, and if they do, how many sprouts there were.
- Callous Wood (Callous wood is the tissue that grows over the pruning wound as the tree heals.): We will be documenting its presence and growth pattern.
What We’ve Found So Far
So far, after looking at the initial data, it turns out there’s no major difference in the amount of damage caused by the different pruners. However, there is a difference in the type of damage. For example, anvil pruners seemed to cause more crushing of the tree’s tissue, while bypass pruners leave a lip of torn cambium and bark on one side.
What’s Next?
While the study is still ongoing, the early results are already helping us understand how different pruning tools affect trees. We’re continuing to collect data on how trees heal over time, focusing on things like new sprouts and callous wood formation. Even though we haven’t seen a huge difference in the amount of damage, the type of damage caused by the pruners could play an important role in how well the tree recovers. This study will help gardeners, arborists, and landscapers choose the best tools for tree health based on how they affect the healing process. Stay tuned for more updates as the study progresses.
Science is fun!
Conducting research, even small studies, is a fulfilling and affirming activity. I left the field feeling invigorated, curious, and enthusiastic. Scientific research at it’s most basic is the act of indulging your curiosity. Do you have a question? Great! How can you test it? What do we need to find out more? What happens when? From the initial question to figuring out the necessary steps for testing to dancing around fire ant hills, playing hide and seek with tree tags and desperately holding onto your record sheets on a breezy day, science is fun!
About this Blog
Rooted 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!).
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