Mysterious tree failure exposed!

end about the tree failure question!  Many of you zoned in on an important point visible in the two photos I shared.  The tree’s base was obviously quite narrow where the trunk broke, and with the tree’s vase-like architecture this led to breakage. But why was the base so narrow?

Again, several of you thought about root issues, such as a restricted root zone, or possible damage to the lower trunk.  Actually, it’s a combination of root and trunk issues, as this last photo shows:

Tree failure 3

What we have is a large circling root (you can see it at the soil surface to the left and right of the trunk) that has girdled the trunk completely and prevented it from growing in diameter.  The trunk above this point continued to grow, eventually creating the instability that eventually led to failure.

This tree used to be the focal point of a small urban landscape.  It was planted about 15-20 years prior to failure and obviously had poor roots.  It irks me that the industry cannot figure out a way to (a) produce trees with decent roots and (b) plant them correctly.  No wonder so many ISA-certified arborists are now recommending that people only purchase bare-root trees, so that these heart-breaking scenarios are avoided.

Congratulations to Jimbo in Australia for being the first to identify this particular problem, and honorable mentions to those of you who had logical and realistic diagnoses for tree failure.

(I hate to take pleasure out of the fact that girdling roots are a significant source of tree failure in Australia, but Jeff and Bert give me so much grief about root washing that I was starting to wonder if it was only the Pacific NW that was cursed with this problem.  Guess not!)

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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

3 thoughts on “Mysterious tree failure exposed!”

  1. Hazar! That's a fine example of what planting stock not to buy!
    I'm happy to say it's becoming less of a problem down this way, Linda. There have been many reputable tree nurseries spring up in the last decade that have addressed a lot of the problems the industry was having back then. That being said, there are still a few cowboys out there. And the home gardener also does not always know how to identify, select and plant good quality stock. We also don't plant many of our trees bare rooted in our public landscapes, especially when the trees are being sourced from a reputable tree nursery.

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