I came across an interesting tree pruning situation the other day… Two of the same variety Dogwood trees where one was exhibiting upright growth habit and the other lateral growth habit. This presented an interesting pruning challenge on how these trees should be pruned and a great lesson in pruning for a plant’s “form.”
A customer had salvaged 2 Dogwood trees from demise some years prior and had planted them on their property in the hopes that they would survive. They did but while one pushed for a central leader to bring itself skyward (referred to as an A-Form tree for Apical dominance) the other couldn’t decide which branch was going to lead the way and laid out more horizontally (referred to as a B-Form tree for Broad or open form). What a perfect scenario to document the difference between A-Form and B-Form trees and how each should be pruned!
Let’s look at the A-Form Dogwood tree more closely…
The first decision to be made was which branch would be chosen to promote as the central leader. We followed the trunk up from the base and the one we chose was neither the tallest nor largest in diameter but rather the clear extension of the trunk. Then we “headed back” the other branches vying for dominance so as to zap some of their energy and redirect the energy to the chosen leader.
Secondly, we looked for any bad branches that may be dying, broken, rubbing or diseased and removed those. Bad branches need to be removed even if it causes poor visual balance because they can be detrimental to tree health if left unattended.
Then we pruned for lateral growth and started to remove the imbalance of the tree to the far left, a number of branches hanging over the walkway and driveway, co-dominant stems competing for the same space on the trunk or too close to each other, and crossing branches. Our limit of canopy removal for this tree was determined to be 30% and we could have easily exceeded that so as we started to approach the 30% limit we did detail work to balance the tree as much as possible.
It was helpful for us to pile our debris as we pruned so as to get a visual indication of how much you are removing (bottom right hand corner). We would have liked to continue pruning this tree but reached maximum 1-year pruning so had to stop. This tree will be pruned again next year and most likely the year after as well. Well maintained trees can be pruned as little as once every 3 years and that is the long term goal for this tree to get it on a 3-year pruning cycle with just minimum touch up during the year.
And what about the B-Form Dogwood tree?…
The first step was to assess whether or not the tree had the ability to support a main central leader. Dogwood trees typically exhibit a moderate apical dominance but this tree had been so abused prior to our customer rescuing it that to reestablish strong apical dominance would take years of training. The time and expense of doing so coupled with the low aesthetic value while the tree was being retrained was not something our customer wanted to invest in so we chose to treat this Dogwood tree as a B-Form tree.
First up was cutting what appeared to be multiple sprouts but were in reality just lateral branches trying to express central leader tendencies (apical dominance). We used mainly “reduction” cuts taking the vertical branches off at the lateral branches. This was different than what we did with the A-Form tree where we “headed-back” the other branches vying to be the central leader instead of taking them off at a main lateral branch.
After reducing the vertical leaders we then checked for and removed any bad branches that may have been broken, cracked, diseased or rubbing.
Then we went into the lateral branches to bring the tree back into some sort of shape. Branches were removed that hung over the sidewalk or were hanging on the fence. Some of the low hanging branches were “removed” at the trunk to get a more moderate tree-like shape. Competing laterals were reduced and branches that were either growing too close to each other or crossing were also reduced or removed.
This tree also reached it’s maximum 30% removal before we were ready to stop so we put this tree back on the list to be pruned again next winter. While both trees could still use some pruning they are now healthier having removed bad branching and much better looking.
A final note: Both trees exhibited stressful conditions during their early years. The A-Form Dogwood had pock marks from where a woodpecker had searched for insects under the back layer. As such, we recommended a deep root feeding to get nutrients and biological life down around the root structure as quickly as possible to help the trees be as healthy as they can be. Good nutrition and proper watering will be important for the long term viability of these trees. For additional information on our deep root feeding procedure go to: https://earthdanceorganics.com/organic-solution-for-verticillum-wilt/.
And for your information: We used 3 pruning-cut terms in this article: Removal, reduction and heading-back. Removal cuts take the branch off at the trunk or point of origin; Reduction cuts takes the parent branch back to a significant lateral branch; And Heading-back cuts shorten a parent branch in between insignificant lateral branches.