Author: 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

A Taraxacum teaser

It’s spring and the dandelions are happy to see you!  I’ve taken photos of two groups of dandelions just footsteps away from one another. The populations are both in full sun, with similar types of soil and water availability. You’ll note that one group has very short flower stalks, while the second has longer stalks:

So what’s responsible for the difference in flower stalk length?  And for extra credit, what’s the scientific term for the phenomenon?

If this isn’t something you’ve noticed before, you will from now on!  Answers Monday!

Organic or local?

I grew up on a small farm (30 or so acres) near Tacoma, Washington. We raised our own Herefords, I gathered eggs from my frizzle chickens, and we all enjoyed apples, plums and cherries from our fruit trees.  Neither of my parents were farmers by profession, though my grandfather owned a dairy farm in Oregon.  Eventually, my husband and I hope to move back to the family farm, if for no other reason than preserve it from the surrounding encroachment of houses.

I’ve been thinking about things I might do for fun or profit on the farm.  Home grown beef for sure.  A veggie garden – finally – on some of the only native soil left in the area.  We’ve got lots of options and the space to try them out.

Now back to the question in the title: organic or local?  Our family property has been managed gently since we moved there in the late 1960’s.  Nothing’s been added to the pasture soil other than what the animals deposited themselves.  We’ve had the apple trees sprayed yearly (a requirement because of apple maggot), but this is a targeted application with little affect outside the trees.  The cattle were never treated with hormones or other additives – they were about as free range as you can get.

I’ve heard from others that organic certification standards have become increasingly difficult to meet and some growers think they have become increasingly meaningless.  On the other hand, locally-grown products are becoming more available.

Is it time for a new standard – locally grown, with some requirements (e.g. soil tests) to demonstrate safety?

Friday puzzle revealed

And we have a winner!  As Karen guessed, these are lichens on decomposing granite:

This photo is from the Fortynine Palms oasis area in Joshua Tree National Monument.  These lichens (symbiotic amalgams of fungi and algae) could be decades or centuries old – they are very slow spreading. 

Most creative answer goes to TT, who thought it looked like sweet potato casserole!  The quartz does look like marshmallows.

Another fine product…

I’m spending this week in Palm Desert, CA for a little R&R in the sun.  In the morning, with my pot o’ Earl Grey, I read the local paper (The Desert Sun).  Last Sunday’s paper provided me with an article about an “intelligent water incubator” (all material in quotes was taken from the article).  Pieter Hoff, a “Dutch scientist, author, and major exporter of lilies and flower bulbs” has invented the Waterboxx, which “produces and captures water from the air through condensation and rain.”  He claims a four year test in the Moroccan Saharan desert showed an 88% survival rate for fruit tree saplings “grown without irrigation.” He now wants to test his invention in the Coachella Valley desert “to create a money-making business model with trees” and of course to help save the environment.

The Waterboxx is a plastic rectangular box, but we’re told the inner technology is more complex.  The box is put around the seed or sapling and provides water “in small doses.”  It also “protects roots against sun, wind, weeds, rodents and some animals.”

I visited the web page and you should too.  The technology section is fascinating.  It includes an animation explaining how the box functions; apparently the box was designed to protect seeds in the same manner as bird poop.  I was interested to see that the box requires 4 gallons of water when it’s set up; not exactly a “no irrigation” methodology.  And that a wick inside the box releases about 50 ml of water a day to the soil below the box.  The last frame tells us “with the waterboxx we can transform most of the deserts into forests.”

I won’t test your patience by dissecting all the silliness in this article and the web site.  As you might expect, there is no peer-reviewed science on this product, nor even a research report.  The plant and soil science is marginal; the ecological science is horrific.  The box effectively prevents water from reaching the soil around the seedling, doling it out in miniscule doses instead.  Not only could a decent organic mulch layer do the same job (and do it better), but I question the “greenness” of creating yet another plastic product with a limited lifespan.   This system is so removed from reality that it’s incredible that anyone takes it seriously – yet it’s been out there for several years now and has won several awards.

Oddly, there’s little specific information about the inventor.   All I could find definitively is that he comes from a bulb-raising family in The Netherlands and has written a book:  CO2 – a gift from heaven (under the name Petrus Hoff).

Friday puzzle answer

So many interesting answers to Friday’s puzzle – thanks to all of you for putting out the effort!  It most certainly is an abiotic problem – but was it temperature, suggested by Deb?  Water, suggested by Foy, Gayle and Ed?  Light, suggested by Nancy?  My plan was to have an extensive soil test run to address the possibility of pollution (suggested by Jim, Heather and Paul), except we discovered the source of the problem last summer when we finished digging our pond:

 

As you can see in this photo, we have solid clay about 12″ below the surface.  (And I do mean solid.  I’ve kept lumps of the stuff to take to seminars, so when people say “I have clay soil” I pull this out and ask if this is what they mean.  Usually not.)


So in this area of our yard we have a perched water table: the water percolates through the topsoil, hits the clay, and spreads horizontally.  When we had turf in place, it tended to keep the upper few inches relatively dry, which allowed the dogwood roots to survive.  When we took out the turf and covered it with wood chips (to conserve water!), the soil became saturated nearly year round.  We dug out the tree a few weeks ago, and this is all that remains of the root system; the rest of the major roots had rotted away:


We’ve replanted the tree in another area of the yard with much better drainage, and we’ll keep track of its establishment and leaf size.  I think it will recover, as new roots will emerge from the main root mass.

(Paul, thanks for the kudos on the fence design!  My husband built this, and he’ll be pleased to see your comment.)

Friday quiz time!

Now I could have sworn I’d posted this puzzle before, but after searching through all the previous postings I can’t find it.  Here it is.

I planted this Cornus kousa in 1999 (removing the burlap, clay, etc. prior to installing).  We removed the turf (still attached to the $(%&$ plastic mesh) and planted the tree in the existing soil.  The first photo was taken in 2004, and the second was taken in 2007:

 

Here are some specifics about what was done to the landscape during this period: we replaced all the turf with wood chips and put in the fence as shown.  There was no impact on structural roots from either of these activities, and fine roots were affected minimally when we dug post holes for the fence.  The turf was simply allowed to die back in the summer (hot summers do that here in Seattle) and then topdressed with wood chips.  There were no chemicals applied, nor was there any soil disturbance.

It was about 2007 that we noticed the leaves were substantially smaller than previous years.  The leaves are sparse and small, but they don’t become chlorotic or necrotic during the summer, nor does any part of the tree suffer more than any other.  This phenomenon has continued until this year, when we finally dug it up and moved it elsewhere.

So here’s the question:  why did this tree start swirling down the mortality spiral?  As always, there may be many legitimate answers – but I’ll show you the actual reason on Monday!

Enjoy your weekend!

Protecting existing trees – what a concept!

I just got back from a trip to Pullman where I guest lecture once a year for the Landscape Plant Management class.  It’s also a chance to get some new photos for my Wall-O-Shame.  Here’s my latest:

Pin oak (Quercus palustris) doesn’t drop its leaves in the winter – instead, they hang on until the following spring.  So it’s really easy to see which part of this tree is alive (i.e., has last year’s leaves).  It’s apparent that most of the crown has died, with only some lower scaffold branches remaining.

How did this happen?  Take a look at how new that concrete is around the base of the tree (and how small the tree well is.  This construction was done in 2004:

Note the complete lack of root zone protection.  Not only has the majority of the tree’s fine roots been destroyed in preparation for pouring concrete, but only a very small space under the tree is “protected.”  I guess the cup at the base represents the irrigation system.  To top it off, this construction was done in August, when coincidentally I was there as well.  It was blistering (as it usually is in the summer in eastern Washington), and the remaining leaves on this tree were wilted:

So why would anyone be surprised when, 6 years later, this tree looks like crap?  And why doesn’t WSU insist on tree protection standards when construction bids are submitted?

Friday mystery revealed!

Good sleuthing over the weekend!  As John, Karen, Jimbo and Al suggested, there is something stuck on the side of this Norway maple (Acer platanoides, which is Latin for “maple that takes over the planet”).  In fact, the reason that I, with my pathetic ID skills, know that it’s a Norway maple is because it’s a nursery tag stuck in the tree:

This type of injury really bugs me, because it’s entirely preventable.  One of the cardinal rules of transplanting trees and shrubs is to remove all foreign material.  And this is a perfect example of why.  I don’t know the history of this tree, but this is was I think happened.

The tag was on a branch of the young tree; as the branch increased in girth, it became girdled by the plastic and died back.  At the same time, the girth of the tree increased to encompass the base of the branch and the tag.  The dying branch was either torn from or broke off the trunk, creating a tear in the bark and creating the horizontal scarring at the base of the wound.

If you’re hopeless with plant names (like I am), keep an electronic database of all the plants you’ve installed in your landscape, including the name, the date installed, and any notes, especially for failures (e.g. not cold hardy enough, invasive, too large, slug snack, etc.).

Friday mystery photo

Today’s photo is courtesy of Photoshop technology.  I’ve edited the damaged area so you can’t see what caused, or at least contributed to, the damage:

Now before you complain that I’m cheating (which I am!) keep in mind that what I edited out could have been removed before you were asked to diagnose this injury.  I will tell you that it’s not due to pests or disease.  As is so often true in real life, there could easily be multiple correct answers.  On Monday I’ll provide an untouched photograph and rail against the all-too-common practice that can cause the damage.

Have a great weekend!