Category: Friday puzzle

Today I’ve attached a photo of a conifer displaying two symptoms:  chlorosis of the older needles and a twisted appearance:

What do you think are the causes of these symptoms?  Answers on Monday!

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 close-up photo for you to analyze and identify:

A more inclusive photo on Monday will solve the mystery.  (Sorry for the brevity – I’m on the road and internet access is variable.  I’m taking what I can get!)

Enjoy your spring weekend!

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.)

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!

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.).

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!

Lots of brainstorming over the weekend, and all the answers were legitimate.  A few people came close with the observation that the roots looked like they had grown over something.  And that’s exactly right:

This is a great example of nurse log decomposition.  When the tree on the right first began growing (and it could have been decades ago), it sent lateral roots out, over, and around the nurse log to reach the soil.  As the nurse log degraded, the tree’s roots were left high and dry, outlining the girth of the original log.

Does this natural example have application in managed landscapes?  Absolutely!  As several of you pointed out, removal of soil or organic matter by erosion or decomposition can leave woody roots exposed.  If these roots are injured by feet or tools, they can lose their bark and become open to disease or pests.  These are the structural roots of the tree, and if their stability is compromised, so is that of the tree.

(Though this tree has had some injury to its roots (probably from hikers), it’s unlikely to fail as it’s pretty small. )

Finally – something else to do rather than post to the IAL blog!  On to today’s photo (and I apologize for its blurriness).

The tree in this photo is alive, and as you can see has structural roots perched well above the soil.  How might this have happened?  There are multiple possibilities.  And secondly, is there a negative impact on the tree, and if so, what?  Answers and another photo on Monday!

Have a nice weekend!