[Arid_gardener] Cottonwood

Tue Sep 18 22:30:40 MST 2007

Mr. Zolnarchik,
Thank you for a really thorough description of the tree and its issues.  

Going through your description, perhaps we can narrow down what the options
are.  

First, the splits in the bark sound like they may be more a symptom than a
cause of the problem. A healthy tree might have that kind of damage but
would readily "heal" itself rather than dry out.  A damaged or dying tree,
on the other hand, might well display large cracks where the bark and
underlying wood has already died.  

The sucker growth you observe sounds like it is marking the point at which
there is still live tissue in the tree.  Some trees in particular will react
to damage or death of the main trunk by putting up this sucker growth, using
the energy stored in the roots.  As you rightly note, this allows for
ongoing photosynthesis and the production of new "food" for the plant.  It
is a safe bet that those suckers are not robbing the tree of nourishment or
vigor, but are instead what's keeping the remainder alive.  

As you say, this has been a brutally hot Summer, and I wouldn't be at all
surprised if the tree had been somewhat damaged by the sewer work last Fall.
Five feet of root is nothing to a tree of 8" diameter trunk, and you can be
certain that the roots extended that far and more.  On the other hand, it's
surprisingly easy to not see a tree root when one is digging, especially if
one is using power tools -- they're easy to cut, they get covered with soil,
and just blend right into the edge of the cut.  

That combination of possible root damage and Summer stress might have been
enough to push it over the edge.  

You mentioned seeing the tree's distress at the end of July.  What did that
look like?  Was it in full leaf, then suddenly lose leaves and develop trunk
splits?  Sudden, or gradual?  Any information on that score would be useful.

Now to the heart of the matter: I agree that a Cottonwood bush is a lousy
thing, and that it'd be a shame to lose eight years' growth, but it sounds
possible that the tree may have already made that decision for you.  

If, as it sounds from your description, the better part of the upper tree
trunk and crown are dead, then there's no resurrecting them.  The tree's
response to the die-back is to shoot the sucker growth, in an effort to stay
alive.  Problem is, the tree doesn't care really if it's a cottonwood tree
or a cottonwood bush, and you do. You might be able to cut down the tree and
carefully keep one of the suckers to make a new tree, but there are a few of
problems with that:

First, you lose your eight years of growth and are starting over anyway;
Second, whatever conditions caused the current tree to fail will likely
do-in the new one; and
Third, that sucker growth is likely to always be a weak tree, even if it
grows.

Sorry to be the bearer of bad news.

The bright side is this, though: I think your tree did you a favor.  

Cottonwoods are notoriously poorly adapted for Phoenix, unless you have a
constant really large water source, such as an open stream or an irrigated
lot.  As that tree got larger over time and needed ever-increasing amounts
of water, it was almost guaranteed to suffer and fail.  And, perhaps more
importantly, even if your sewer wasn't damaged by the cottonwood this time,
at only five feet away it was only a matter of time before it did -- the
cottonless cottonwood is famous for invasive roots.  

The good news is there are some really wonderful large tress that do well
here and might make good replacements.  The Sissoo, or Indian Rosewood,
grows to a beautiful large tree, it's evergreen, and it grows quickly -- its
growth in 8 years would put your cottonwood to shame (plant it small so you
don't have to stake it, and it will grow like mad).  The Chinese Pistache is
slower, but it gives you beautiful red fall color before the leaves fall for
the Winter.  The Chinese Elm is a graceful and very pretty tree that will
grow well once it's established.  The Live Oak is a moderate grower that
develops a very stately form.  And there are of course numerous very fine
desert trees that do well here, and a good nursery (Baker, for example) will
be able to tell you all about them.  

There may be an arborist on this list-serve who could give you some
additional information, but it sounds to me like your tree has decided to
become a bush, and your best bet would be to start over with a healthy and
well-adapted replacement.

I hope this helps.
Thanks much,
Tyler

tyler at tylerstorey.com
http://tylerstorey.com
602-738-2978

-----Original Message-----
From: arid_gardener-bounces at CALS.arizona.edu
[mailto:arid_gardener-bounces at CALS.arizona.edu] On Behalf Of
carlzolnarchik at cox.net
Sent: Tuesday, September 18, 2007 2:08 PM
To: arid_gardener at Ag.arizona.edu
Subject: [Arid_gardener] Question from Home-Hort WWW page

Carl S. Zolnarchik
85037
carlzolnarchik at cox.net

September 17th, 2007

Hello:

I am a homeowner living in Central Phoenix.

I  have an 8 year old "Cottonless" Cottonwood Tree planted in my front yard
in full sun exposure.  It's trunk is approximately 8 inches in diameter.
The bark in places has split and apparently this has caused a drying effect
on the interior of the tree. 

The only green growth now is approximately 4 feet above the ground and
consists of a solitary "sucker" of growth coming out of the trunk at that
height and numerous well leaved quite hearty "suckers" rising up out of the
base of the tree.  Also one "sucker" arose from the ground approximately 6
feet from the base of the tree but when I investigated to see if it was a
"new" different tree of the same variety I discovered it was only still
another sucker attached to a shallow root of the diseased/dying/drying tree.
That last sucker was too close to my carport driveway so I exposed the root
with a shovel, clipped off the growth and reburied the root (without
severing the root). 

2007 has been a brutally hot summer...

A sewer line running past the tree approximately 5 feet from the trunk was
replaced during the fall of 2006 and the contractor left the trench open for
about 3 weeks.  This also may have contributed to stress on the tree
although the contractor indicated no root intrusion into the sewer line and
claimed his excavation did not encounter any "major" tree roots...

I have been watering the tree thruout the summer vigorously from the point
that I noticed it's distress.  (About 90 minutes to 2 hours every 2nd or 3rd
day)  Approximately since the end of July...

The tree appears therefore to be alive!

My quandry is what to do now.  I've left the suckers grow hoping the
watering and photosynthesis will nourish the tree sufficiently to save it.  

What are your suggestions?  Would if be better to refer me to another
aqriculture contact?

My wife suggests removing all the "suckers" but I disagree as that would
leave the tree with no green growth at all to be nourished by
 the sun.  I DO NOT WANT A COTTONWOOD BUSH. HOWEVER.  I want a tree....

Should I continue as I've been doing letting the suckers grow and watering
vigourishly?  

Should I trim/cut back the tree to the highest green growth remaining?
(note the ground  level suckers are doing much better than the solitary one
about 5 feet up from the trees base so I'm not sure if the ground level
suckers are robbing this solitary growth of nourishment and maybe even the
whole of the rest of the tree of moisture and nourishment as well...

Should I only trim the smaller obviously dead branches and leave the trunk
intact?

Should I practice "benign neglect" and water the tree normally as the fall
air temperature's drop, avoiding any trimming, cutting, or removal of
suckers and branches or cutting the trunk and let nature take it's course to
see if the often hearty cottonwood species revives my distressed tree on
it's own?

I hope you have an arborist or horticulture specialist who can answer my
questions. 

 I'd rather not cut down this tree and plant a new one losing 8 years of
growth;  however I don't know if this tree is dead above the highest green
growth remaining and destined to become a bush and therefore should be
removed...Or if the suckers will merge as they grow into the tree trunk
itself as branches of "Mulberry Trees" often do and the trunk will simply be
thicker and the upper levels of the tree will reinvigorate themselves.

Can you help?  Or can you refer me to someone who can?

I am disabled and live on a low fixed income so hireing an arborist to come
examine the tree or a "tree surgeon" to come diagnose and heal it if
possible is not truly an option if such would be expensive.

Sincerely,

Carl S. Zolnarchik
3002 North 87th Ave.
Phoenix, Arizona 85037-3308
Email: carlzolnarchik at cox.net
Phone: (623) 872 - 5310  (I'd prefer email or written contact)

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