“Why Topping Hurts Trees” is a best-selling consumer education brochure published by the International Society of Arboriculture. Arborists buy them in bulk quantities to give to customers who think they want their trees topped. Homeowners sometimes feel that their trees have become too large for their property, and people fear that tall trees may pose a hazard.

Arborists often find themselves in a position of trying to convince their clients that topping trees can make them more hazardous in the future, can lead to internal decay, will stress the trees through starvation, and makes them downright unsightly. “Why Topping Hurts Trees” can help explain these problems, with the full weight and credibility of the ISA behind the message.

I’d be willing to bet that every arborist reading this column already knows these things, and probably has experience in educating homeowners about the potential harm in topping trees. Explaining the perils of tree topping to homeowners is one thing, but explaining the perils of “tree experts” is something else.

 Arborists should follow the ANSI A300 Pruning Standards and the ISA Best Management Practices: Pruning. Photo: ISA

Arborists should follow the ANSI A300 Pruning Standards and the ISA Best Management Practices: Pruning. Photo: ISA

I frequently speak at conferences, and one of my favorite topics is pruning. I’m often approached afterward by arborists, or others engaged in tree work, with a common question: “What can I say to clients who still insist on having their tree topped, even after I’ve explained why not to do it? Sometimes they tell me that if I don’t do it, they’ll find someone who will.”

The most emphatic and personally satisfying answer is clear: “Your reputation is worth more than that one job – walk away from it.” That answer, however, does not provide much of a foundation to build upon, and might not be enough for someone struggling to build a business.

Actually, the question is made a bit more complex by the things I preach in my seminars. I like to say that most of the time we prune trees for “people reasons”: to reduce potential hazards, clear street signs and structures, allow more sunlight to the grass or understory plants or to improve aesthetics.

There are some reasons to prune trees to improve tree health, but they don’t apply to most of the pruning performed on a daily basis. In fact, much of the pruning we do compromises tree health by reducing photosynthetic capacity and inflicting wounds. Nevertheless, if trees and people are to coexist in an urban environment, arborists will always play a role in making the compromises between tree health and societal functions. Our recommendations should be founded on the best research-based information available.

So, I’m often asked: If professional pruning generally compromises tree health and we prune trees for people reasons, why not give the clients what they ask for?

In response, I ask the arborists if they understand how topping can make trees more prone to failure in the future (decay, weakly attached sprouts, etc.). The answer is almost always yes. Then I ask them to imagine the following scenario.

Against your better judgment, you acquiesce and top your client’s silver maple tree. Your client is satisfied, pays you promptly, and everyone goes away happy. Three years later, a portion of the tree fails in a windstorm and kills the neighbor’s child. The neighbor files suit against the client, against your company and against you personally. Attorneys are hired and begin to build their cases. The attorneys discover, with no difficulty, that our profession has A300 Standards and Best Management Practices that clearly state that topping is an unacceptable practice. The Arborists’ Certification Study Guide and the Introduction to Arboriculture CD-ROMs have detailed explanations of why topping is bad for trees. And even ISA’s consumer education brochure, “Why Topping Hurts Trees,” starts off with, “Topping is perhaps the most harmful tree pruning practice known.”

The next step for the attorneys is to get expert witnesses. Lo and behold, professional arborists are lining up to testify that:

1 Topping is an unacceptable practice.

2 Any reasonable and minimally educated arborist knows this.

3 Topping can make a tree more prone to failure in the future.

4 And, (the nail in the coffin) topping this particular tree could be considered a proximal cause to its failure.

This is a grim scenario, but it’s plausible and similar to some real cases.

As arborists, we are professionals, and we have an obligation to conduct ourselves in a professional manner and adhere to the standards and best management practices that our profession has established. For most certified arborists, the knowledge that topping can hurt trees is enough for them to steer away from the practice. Perhaps for others, an understanding that topping a tree can lead to the loss of life, the loss of their business, or a possible criminal negligence conviction will convince them to stop the practice.

I look forward to a day when a true commitment to safe, healthy trees guides how arborists practice their trade. Moreover, I look forward to a day when professional ethics overcome the desire to make a few dollars by performing substandard practices.

To those conscientious arborists who are dedicated to the professional practice of arbor-iculture according to accepted standards of practice, we must resist the urge to condemn and banish the tree toppers in our communities. The condemnation path hasn’t worked; it has further alienated the perpetrators, and every tree they top they continue to mar our professional image. Instead, we must seek to educate them and bring them into our ranks. If it isn’t enough to know how topping hurts trees, perhaps the next lesson is how topping hurts arborists.

This article is adapted with permission from the International Society of Arboricultureand originally appeared in Arborist News.