Dying dogwood diagnosis

Lots of good, thoughtful answers from you over the weekend about these trees.  Here’s another photo from a bit farther away:

As Laura pointed out, there’s a relatively new parking lot here.  The creation of the parking lot both compacted the surrounding root zone, then covered it with impermeable surface.  The dogwoods are huddled on their little island, which is unirrigated, unmulched, and indeed hot in the summer as Daniel said.  All of these environmental insults, in addition to the mature age of these trees, have led to what we call a “mortality spiral”:  trees are environmentally stressed and then become more susceptible to opportunistic pests and diseases.  Jon and Wes both did a nice job of discussing this.

There’s a couple of take-home messages here:

1)  If you must disturb a significant portion of an existing tree’s root zone, you should both protect the zone from undue compaction during construction, and then follow up with heavy-duty aftercare of irrigation and mulching.

2)  If you can’t follow point #1, then for heaven’s sake just remove the trees when they start their inevitable failure.  “Lingering death” is not an attractive landscape theme.

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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

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