I see the light!

Here’s the follow up picture from Friday’s puzzler:

As you can see, there’s a street light near the lower half of the maple.  (I cleverly hid it behind the utility pole in the first photo.)  The green part of the tree never received the message that days were getting shorter, since the street light is bright enough to interrupt the dark period necessary to initiate dormancy.

This is one of my favorite phenomena unique to urban environments.  It doesn’t appear to hurt the tree, although the green leaves will die before the tree can scavenge their nutrients.  If more of the tree were affected, I’d be more concerned.

Congratulations to Planting Oaks, who nailed this right off.  And kudos to those thoughtful alternative explanations, all of which could logically have had an impact on color change.

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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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