What we’ve been up to:

On a sunny day in April (the day before my birthday in fact) I spent a joyful hour in a field of young oak trees. Was I perusing the branches for birds or sitting idly with a book of poetry in hand? Maybe I was on my way somewhere, a wander to wonder? On the contrary, I was doing SCIENCE!

You may remember from our previous blogs introducing the topic and discussing our initial findings, that the ‘Show us the Data!’ team has been hard at work trying to answer the question of which hand pruner will rule them all. We hypothesized that the type of hand pruner, Anvil or Bypass, does not significantly affect presence or number of resprouts or the growth of callous wood.

To assess the intermediary damage to stems, we spent that sunny hour in April documenting the presence and degree of discoloration (an established metric for determining damage to the vascular system) as well as the presence and number of new sprouts. Sprouts were counted if they originated from the closest node (growth point on the stem, often where buds, leaves and new stems emerge) to the pruning wound. The degree of discoloration was based on a 0-3 scale, where 0 was no discoloration and 3 was severe discoloration.

The data:

Using data sheets organized by Branch ID and pruner type, we documented the degree of discoloration for each stem (me climbing into, under and between the tree branches, lab manager Joe finding tags and Andrew the diligent note-taker), the presence and number of new sprouts, as well as any relevant notes. There was no correlation between pruner type and the presence or number of new sprouts. But….

All stems showed some amount of discoloration. 

The degree of discoloration ranged from mild to severe, no severe discoloration was observed on the stems

trimmed with the small bypass pruners, but the most stems with severe discoloration were found on the stems pruned using the big bypass pruners. There were more branches with moderate discoloration found on all branches pruned using anvil pruners with 16 branches showing moderate discoloration and 4 showing severe discoloration. In comparison, bypass pruners showed moderate discoloration on 11 branches. Despite a seeming trend toward more severe damage on branches pruned by anvil pruners, after running a quick test for significance, none was found (P-value of 0.44). It is important to emphasize that while the chart to the right might lend us to assume significance, none actually exists.

What happens next?

We will continue to monitor the development of sprouts and callous wood on the pruning wounds over the next six months. As I gain confidence in my statistical analysis, I look forward to getting more data to feed into existing analysis and learn more. Stay tuned for more updates from the field!

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!).

Want to see more? Visit our archive.

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