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Nothing heralds the
arrival of the desert
spring (and in some
year’s 100 degree
temperatures) as
brilliantly and
conspicuously as the
blooming of the Palo
Verdes. With a
succession that includes
Blue (Cercidium
floridum), Foothill,
Mexican and Sonoran,
Palo Verdes color the
desert a brilliant
yellow from spring to
early summer. Other than
Mexican Palo Verde (Parkinsonia
aculeata) all
the Palo Verdes are
popular and widely used
landscape trees. All
these species are so
closely related
botanically that
hybridization between
species is quite common
in native and nursery
environments. In the
past this hybridization
went largely unnoticed
or was mistaken for
genetic seed variation
within a single species.
The potential for
Cercidium hybrids to
offer genetic advantages
like increased vigor,
greater cold hardiness,
enhanced flowering and
the absence of thorns
brought them to the
attention of
horticultural
professionals and
propagators.
Cercidium (Parkinsonia)
hybrid ‘AZT™’
exhibits the form,
structure and grace
found in Palo Brea, Blue
and Mexican Palo Verde
in combination with a
leaf canopy that
provides ample shade
with lush, green leaves.
These trees are
thornless and produce
brilliant yellow flowers
abundantly in spring,
intermittently during
the summer months and
occasionally in the
fall. Similar to the
Palo Brea, the branches
and trunks of variety
'AZT™' remain a smooth,
lime green as they
mature and possess the
genetic versatility to
be grown as either
V-shaped upright or
candelabra form
specimens. The
orientation and angles
of branches are also a
bit reminiscent of Palo
Brea making the trees
excellent “focal point”
single specimens, theme
trees, street and
perimeter planting and
can be dramatically
up-lit at night.
Cercidium hybrid ‘AZT™’
has 4 to 6 pairs of
leaves with 15 to 24
pairs of leaflets per
leave. These highly
divided leaves produce a
canopy that is lush yet
airy and provides
welcome filtered shade
that promotes flowering
of under-story shrubs
and groundcovers. This
hybrid is thornless, and
a semi-evergreen
growth.
Variety
'AZT':
More than a decade ago
Arid Zone Trees (AZT™)
began vegetatively
propagating (cloning)
some of our most popular
desert adapted tree
species. This process
involved: 1) identifying
trees that had both
desirable physical
qualities (branching
habits, leaf color, leaf
canopy, and flower
color) and sound
horticultural
characteristics
(rooting, cold hardiness
and growth rate); 2)
developing propagation
techniques that allowed
the large scale
vegetative propagation
of the selected trees;
and 3) growing these
selections to market
sizes for additional
nursery evaluation and
field testing in
landscape setting. This
tree is the product of
our research and
evaluation. We have
identified each of our
clone species with the
variety designation
‘AZT™’. Our
rigorous screening and
propagation process, in
combination with AZT™’s
Root Management Program,
insures that Cercidium hybrid ‘AZT™’ brings
beauty, durability and
sound genetics to desert
landscapes.
Cercidium hybrid ‘AZT™’
we are so confident of
the quality, we put our
name on it.
Cercidium (Parkinsonia)
hybrid 'AZT™'
is propagated and
available exclusively
from Arid Zone Trees.
Cultural Practices:
Foster the development
of a more dispersed root
system and reduce the
risk of wind throw by
arranging irrigation
emitters at varying
distances from the trunk
to encourage roots to
"seek out" water and
nutrients. Irrigation
emitter arrangement
along with other
information on
irrigations practices
for desert trees can be
found at
Irrigation Practices for
Desert Trees.
Prune as needed to
reinforce the structure
and form of the tree.
Periodic thinning is the
most desirable method of
pruning. Avoid hedging
or heading back desert
species, as this will
only stimulate excessive
branching. Do not remove
more than 30% of the
canopy during the summer
as this can lead to
sunburn injuries that
can later be invaded by
wood boring insects.
Always use clean, sharp
tools that are cleaned
regularly in a 10%
solution of bleach. For
detail pruning guide see
Pruning Desert Trees.
Periodically
insect pests can be a
problem on some desert
trees. On young trees,
insect infestation can
slow typical seasonal
growth. Inspect trees
during the growing
season for common garden
sucking insects such as
aphids, thrip,
whiteflies or psyllids.
During dry months, (May
and June) in dusty
conditions, spider mites
can appear. Monitor for
infestation and apply
controls as needed.
Spray applications of
water or water and Safer
Soap give short-term
control (3 to 7 days)
for small insect
population. For heavy
infestation or longer
control use federally
registered insecticides.
A contact insecticide
application will kill
existing adults. An
application with a
systemic soil drench
will provide 8 to 12
weeks control for any
post application insect
hatchings or migration
of insects. Before using
pesticide for the first
time or on new plants or
cultivar, treat a few
plants and check for
phytotoxicty.
Always read label and
follow label instruction
before using pesticides.
For pesticide control
recommendations contact
a
licensed pest control
advisor.
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