[Arid_gardener] New to the Desert

[Olin Miller]

Railroad Ties
Many people use railroad ties with no apparent bad effects but I would 
not use the ties to enclose a vegetable garden.  Even if you use the 
heavy 8 mil plastic, it will deteriorate within a few year in our high 
heat and blazing sun.

Bermudagrass
It probably depends on the size of your garden.  For small areas, it is 
feasible to dig the dirt down to about one foot and screen it through 
1/4-inch hardware cloth, then put it back.  Some people would recommend 
2 feet but the roots that spread are usually within the top one foot. 
For a large area, I would go with the Roundup solution as outlined in 
the publication, "How to Eliminate a Bermudagrass Lawn Using Glyphosate" 
at
http://cals.arizona.edu/pubs/garden/az1371.pdf

Pruning Newly Planted Jacaranda
>From http://cals.arizona.edu/pubs/garden/az1139.pdf

"PRUNING YOUR TREE AT PLANTING TIME:

 There is no need to prune a newly-planted tree unless branches have 
been damaged. It has been found that removing tips and buds of young 
trees slows root growth. If trees are left unpruned, expanding buds and 
new leaves help root expansion and tree establishment. Damaged branches 
can be removed at their point of origin, or they can be cut back to a 
lateral branch that will provide foliage and help establishment the 
first season. "



Pruning Mesquite

Also from http://cals.arizona.edu/pubs/garden/az1139.pdf



When to prune a deciduous tree

 In general, pruning has a greater benefit if it is performed while the 
tree is young. Wounds are smaller and recovery is more rapid. This 
document will discuss pruning young trees and older trees separately. 
Deciduous trees are those that lose their leaves and go through a 
dormant period in response to cold (and sometimes drought). The best 
time of year to prune is during this dormancy — when all of the foliage 
has dropped. Generally this occurs from mid-December to the latter part 
of January ... All pruning should be done before buds show evidence of 
swelling. Why?

 • Less likelihood of tearing bark

• Less likelihood of dripping sap

• More time for recovery before bud break

• Easier to see branch structure

• Less likelihood of stimulating unwanted growth"



If it were my tree, I would prune it now to get it out of the way.



Pruning Sealer

>From http://www.cahe.nmsu.edu/ces/yard/2001/021001.html

"Why not use pruning sealer?

"It does seem counter to common sense to leave a wound uncovered when we 
consider it from a human perspective. That is the way we tend to think 
about wounds, but remember a tree is not a human, or even an animal, and 
responds to things in a different manner. In the natural environment, 
branches break from trees in wind storms and must have a mechanism to 
defend themselves without a gardener going into the forest and applying 
wound sealer to every injury. Certainly, some of these cause problems 
for the tree, but in many cases the tree has the natural defense 
mechanisms to manage the problem.

A tree doesn't ""heal." It only closes over the wound, enclosing the 
damage inside the tree. It has the ability to compartmentalize diseases 
and damage tissue sealing them from the healthy tissues in many 
instances. These damaged areas then remain in the tree and can be seen 
many years later if the tree is cut. It is possible to see scars 
(compartmentalized damage) caused by fires 50 and 100 years before the 
tree was finally cut. There are instances when the damage to a tree is 
too severe and the tree rots internally, but such damage cannot be 
stopped by a pruning sealer.

Some people think that pruning sealer will help prevent the tree from 
"bleeding to death." Trees don't bleed—they don't have blood. The blood 
in an animal is critical because it carries oxygen to all the cells 
within the body. Plant sap carries water, minerals and sugars, but does 
not carry oxygen. Loss of blood in an animal will cause cell death for 
lack of oxygen. Plants don't have this problem. They can lose a lot of 
sap without major injury. The dripping sap just irrigates the tree. 
Pruning sealers will have little effect in reducing the dripping of sap. 
It just stops naturally as the tree compartmentalizes the wound.

Many pruning sealer compounds are black and contain asphalt. This black 
material absorbs our New Mexico sunlight and becomes quite hot. The heat 
can kill the tender cells that the tree produces to close the pruning 
wound and in that manner delays wound closure and compartmentalization. 
Lighter-colored materials do less damage, but any containing a 
petroleum-based solvent can damage newly developing wound closure cells.

Scientific research has shown that the pruning sealer is not necessary. 
Much more important is proper pruning technique. Knowledge of tree 
anatomy and physiology allows us to prune a tree and allow the tree to 
use its protective mechanisms to protect itself. It is also wise to 
minimize pruning in landscape trees by training a tree when it is young. 
Cutting small branches when the tree is young precludes the necessity to 
cut larger branches later. The large wounds produced by removing large 
branches create greater difficulties for the tree"

Olin Miller
Master Gardener Volunteer, Maricopa County AZ
"The opinions or statements expressed herein are my own and should not 
be taken as a position, opinion, or endorsement of the Maricopa Master 
Gardener Association or of the University of Arizona."

======================================================
----- Original Message ----- From: "Renee Zuck" <reneezuck at go.com>
Sent: Friday, May 12, 2006 10:27 AM
> ... we are putting in a raised bed vegetable garden using railroad
> ties.  This area previously had bermuda grass which we dug up and are
> planning to put down some soil acidifier, then a weed cloth and then
> topsoil.  We are planning to place plastic around the railroad ties to
> limit the creosote etc. that might leach.  They are fairly old ties.


> Do you have any other suggestions for keeping the bermuda grass at
> bay?
>
> What should we do with the dirt and Bermuda grass that we've dug up?
> Can it be composted?  Should we just throw it away?  Can we separate
> out the grass and then use the remaining dirt as fill in for the
> vegetable bed?
>
> Do you have any other suggestions for the railroad ties in terms of
> limiting creosote leaching?
>
> We have a jacaranda tree that we just had planted.  It has some
> branches growing out very close to the base of the trunk.  Is it OK to
> prune these or should I wait until the tree is more settled?
>
> I also have a mesquite tree whose branches are blocking part of the
> entryway to our house.
> Is it OK to prune now, should I wait until the tree goes dormant?
> Should I use tree seal when I prune or just leave the cut alone?  I've
> read desert gardening books that have differing opinions on this.