*Jeremiah originally wrote this article for the Tree Care Industry Magazine. It was first published in the June, 2021 issue.*
The Epicormic Conspiracy
Despite the tremendous volume of literature and material available on tree biology and tree biomechanics, one of the most common sentiments heard from tree workers and salespeople go something like this:
“We’ve gotta remove those suckers because they steal energy away from the tree!”
After a major crown failure in the past, this willow’s new crown is mostly formed by epicormic growth. Here, Jack examines a possum’s habitat while pruning in Detroit.
This type of statement is expected from homeowners who aren’t well versed in tree science. It’s an arborist’s role to advise them, after all. As a person who cherishes their role as an arborist, hearing this from tree workers and seeing the amount of improper pruning is disheartening. Aren’t we supposed to be the “tree experts”?
The word “sucker” definitely sounds bad, so they must be bad, right? But it’s a misnomer; plain and simple. Epicormic growth has many roles in tree biology, and they don’t suck at all. Tree biology informs us that epicormic growth isn't “parasitic” to the tree. They aren’t “taking away nutrients” from the tree. They are the tree.
The entire notion is hilariously inaccurate. I suspect “parasitic” epicorms earned their misnomer in order to keep tree workers busy; to keep the money coming in. Stubborn commitment to “the way we’ve always done things” or “that’s what the customer wants” is going to keep your company behind.
Only a single grain of truth
As epicormic sprouts begin to grow, they do not have leaves on them. They aren’t self-sufficient in their initial phases of growth; they aren’t producing their own carbohydrates from their own leaves. They are being generated from stored carbohydrates.
In this way, one could say they are “taking” energy away from the tree (which is still a bit of a stretch). But, as soon as an epicormic shoot has leaves on it, it begins to “fund” itself with its own carbohydrates. From here, it isn’t relying on stored energy to grow. It isn’t an issue that the tree is spending stored carbs to initiate new epicormic stems; that’s why it stores them in the first place.
Epicormic growth is the sign of a tree functioning properly. It is not a malfunction of trees.
Epicormic growth to the rescue
Above all, epicormic growth is a response to a stressor. The need for more carbohydrates is to deal with stress, such as being pruned or part of the aging process like retrenchment. Some trees will activate epicormic growth in the absence of stress, such as some Tilia species or some Quercus species.
A fully retrenched crown of an ash tree in Royal Oak, MI
This amazing ash tree has grown an entirely new crown thanks to epicormic growth. If these epicormic were frivolously cut off, this tree would likely be dead. It is known that leaves and stems at different places in the crown serve different functions and are constructed differently. All parts of the tree are doing something for the tree. Removing these doesn’t do anything proactive for the tree.
However, there are reasons to remove some epicormic stems. For instance, if the stem grows such that it will eventually form a major inclusion as it grows, it is worth removing. Instead of cutting them all off, the appropriate response to seeing a tree with a significant amount of epicormic growth is to ask questions.
Has something changed in this tree’s environment in the last decade? When was this tree last pruned? And by whom? How long ago was this driveway installed next to the tree?
A true arborist will disclose to a customer why “cleaning out” the interior of their tree isn’t a good idea. They’ll try to get to the bottom of what the tree is expressing.
Let’s Call a Spade a Spade
What makes the epicormic conspiracy hilarious is that it does the exact opposite of what it is claiming to do.
To be concerned with a tree’s energy state would direct the focus away from pruning, not towards it. Removing carbohydrate sinks and removing photosynthetic area is, by definition, stealing energy away from trees.
Lion-tailing and gutting the interior of a tree because customers want that isn’t tree care; saying “yes” to a customer’s every request isn’t always tree care either. That’s customer care. While that is important, let’s call a spade a spade. Tree care is tree first. An arborist, in the truest sense of the word, cares about the tree first and foremost: an arbiter for trees.
Suckers
The industry itself has perpetuated this deliberate falsehood. There is an abundance of ‘tree experts’ who are not well versed in tree biology; they’re experts in tree work. Since we’re the ones who got it stuck in peoples’ heads, we should be the ones to get it out of their heads.
The epicormic conspiracy is a reflection of where our industry is today. We have the tools and the information to stop being suckers ourselves. So why haven’t we? The business of tree care gets in the way of itself here.
Companies with a stern commitment to the old dogma will get left behind to scientifically literate companies who are willing to explain things to customers; who are willing to say no, willing to refuse to do malpractice, and above all, do what’s right for trees.
Trees are resilient, but we have a responsibility not to abuse that. There are plenty of more meaningful things we can do to trees that actually benefit them instead of damaging them.
The quality of tree care is only as good as the hand that cuts—or the hand that doesn’t cut.