Update on root-rotted Cornus kousa

A little more than a year ago I posted a Friday quiz based on a failing Cornus kousa.The answer explained that our landscape has, in part, a perched water table that effectively rotted most of the roots of this poor tree over several years.  Last spring we moved it to a different section of our landscape where we know the drainage is better, and I’ve been monitoring its recovery since that time.

Cornus kousa leaves in 2007

Cornus kousa leaves in 2011

We were gratified to see that the leaves this year are significantly larger than those of previous years.  This tells us that root function has resumed, providing enough turgor pressure to expand the leaves to normal size.  It was especially helpful that we had one of the rainiest springs on record.

Take home lesson:  if a tree or shrub is failing in its current location, it’s worth digging up to see what’s going on.  Bad soil conditions?  Move it to a better location.  Bad roots?  Time to hone your root pruning skills.  But wait until fall to do this.  Transplanting this time of year is the most difficult for plants because of the increased water demands of warmer temperatures and expanding leaves.

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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 "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

2 thoughts on “Update on root-rotted Cornus kousa”

  1. We had a situation with a pagoda dogwood that it was sited improperly with our sandier soil. Dug and moved to part of the yard with more loamy soil and the plant adjusted very well!
    Good to see yours is recovering!

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