[Arid_gardener] Why are my Palo Brea Trees suddenly dryingup/dieing?

[Olin Miller]

After 7 years, the roots of your tree "a few feet from the lawn" will
extend 1-3 feet beyond the edge of the tree's canopy and tree well into
the lawn area thus receiving the same amount of water as the lawn - not
good.

>From "AZ1048 Care of Desert Adapted Plants " at
http://cals.arizona.edu/pubs/water/az1048.pdf

"How To Irrigate
Light, frequent irrigations create shallow, weak root systems. Deep,
less frequent irrigations encourage deep strong root systems that can
tolerate longer periods of drought. Mature root systems are typically
1½ -4 times wider than the plant canopy. Rooting depths vary depending
on plant type. Always irrigate the entire depth and width of the plant
root zone regardless of the time of year. Irrigation frequency is
dependent on how quickly the soil dries out. Soil texture and plant
rooting depth will determine the length of irrigation time; water will
move down quickly in sandy soils and slowly in clay soils. Use a soil
probe, a long screwdriver, or a piece of rebar to determine how deeply
and widely the water has moved. When dry soil is reached the device
should stop. To prevent runoff don't apply water faster than the soil
can absorb it. Use drip irrigation, a soaker hose, or a slowly dripping
garden hose to reduce the flow."



The publication also has a diagram showing the recommended emitter
placement.



The chart "Landscape Watering Guidelines" at

http://www.cityofmesa.org/utilities/conservation/landscape__watering.asp

summarizes the recommended watering schedules and amounts for various
landscape plants. Use the schedule for Desert Adapted Trees.


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: "Brian Stockdell"
<brian.stockdell at psware.com>
Sent: Thursday, May 11, 2006 10:00 AM
> REQUEST ASSISTANCE with specific plant problems.
> Detailed information:
>
> ~ Palo Brea Trees that are about 7 years old.
> ~ Description of the problem: One tree showed signs of stress a few of
> months ago along with brown "ulcerations" that I have seen on many of
> these
> trees around town, but was flowering and putting out leaves.  This
> week,
> virtually overnight it and two other Palo Brea trees the same age had
> the
> flowers  and leaves dry up on many to most of the branches.  The one
> that
> was showing stress previously has a large portion of its branches
> drying up.
> ~ Location of the plant:  These trees have full sun and are planted in
> arid
> landscape a few feet from a lawn.
> ~ How often you water the plant:  This trees and surrounding plants
> are
> watered via the original drip system for 30 to 45 minutes every 3 to 7
> days
> depending on the season.  Two of the trees were deep soaked a couple
> of
> times in the last month because of the one tree showing some stress.
> ~ Other plants in the vicinity affected:  NONE.  Other plant types
> under and
> nearby the trees are not effected.  A 4th Palo Brea tree on the other
> side
> of the driveway looks good.
> ~ Other things that might be affecting the plant : A landscape company
> has
> recently fertilized the lawn and sprayed for weeds.  They have done
> this
> periodically for years.
> ~ What do you think the problem might be and why:  Normally, I think
> that
> they are not getting enough water, but established trees like these
> don't
> need much water.  In fact, from what I have gathered about this tree,
> heavy
> watering might actually be the wrong thing to do.