Here is this week’s plant puzzler. This mature tree just fell over one summer day. There had not been any significant wind, the soil was well-irrigated (but not overly wet), there had been no construction work or other root-zone disruption. There were no significant pest or disease problems. I’ve posted two photos from different angles, and will show one more photo on Monday. Why do you think the tree failed?
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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 a 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
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Books: http://www.sustainablelandscapesandgardens.com
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That's a pretty small area for such a large vase shaped tree. Perhaps competition from the groundcover/shrubs and constricted area prevented it from growing adequate roots to anchor such a tall tree.
You've got on three sides two sidewalks and the concrete house foundation which could block roots.
Based on the shape of the tree it looks pretty tall and top heavy.
Age, and the overwhelming weight of multiple, leaf heavy trunks?
Weed wacker or lawn mower damage?
I'd be more inclined to say poor planting stock. The amount of young trees I've seen with root curling and j-rooting being put in landscapes is terrifying. They're accidents just waiting to happen. A lecturer of mine told a funny story regarding a new Melbourne housing estate back in the 80s, and the planting stock they used as street trees. The stock was poor to say the least. He was called out as an expert arborist to consult on why the street trees weren't doing so well about a year after they were planted. He and a colleague went down one street of the new estate and simply pushed and pulled on the young trees' main stems. When the stem didn't flex, but rather moved at the base, they began pulling the trees out of their planting holes with little to no effort. Every single tree on the estate was root bound at the time of planting and consequently hadn't grown lateral roots beyond the original coiled root mass. The housing estate developer had to replace every. single. tree. I'll say the same thing has happened here.
Mower blight damaged the bark- the interior rotted leaving only a cylinder of good wood to support the tree. The trunk looks like it snapped off just above ground level. We lost a 350 yo oak in a similar way. Early fall, ground dry, no wind, midday "Craaaccckkk" and "Thud", a big cloud of dust and a bunch of shocked and saddened people.
I agree with SJ — little room for rooting. But the tree obviously did root in and grow to that size. Hard to tell from the photo, but was it sitting on/next to a boulder or piece of ledge? What baffles me is the breaking off at the trunk. The tree's sitting in a planting bed, where weed whackers and mowers would be unlikely to go. Damage low on the trunk often comes from some kind of bad root issue, like the kinds Jimbo describe. So maybe it was the lack of rooting space, and the tree hit some kind of ultimate tipping point (so to speak) underground, which translated to trunk trauma, and then that big canopy caught a high wind? Hmm. Still — perhaps there's more to the story.
It seems like the tree could have been buried too deep and broke at the point it was rotted.
My suspicion: either a mulch volcano or soil added around base of tree leading to crown gall or some other rot.
I think it's girdling of roots that caused the tree to topple over. Good thing it didn't land on the house!!!
Ok. Here's another idea. The tree being planted in an area surounded by sidewalk,house,drive was essentially planted in a "container". Such sitings usually include no removal of burlap, twine, basket, etc. A "quick & dirty" planting of a big-impact tree is only temporary. Ka-boom!