For
year-round beauty and
sheer volume of spring
color, few
desert-adapted trees can
rival the Blue Palo
Verde, Cercidium
floridum. Blue-green
bark, smooth on younger
branches but becoming
more grayish and
fissured as trees
mature, gives color to
the graceful trunks and
highly divided branches
while providing a dark
green backdrop for the
intense yellow spring
flower display. Flowers
first appear in early
spring and may persist
into early summer. In
mature, vigorous
specimens, flowers
literally cover the leaf
canopy, creating masses
of yellow in the
landscape or dotting
desert hillsides. When
properly pruned, the
trees reveal the color,
texture and sculptural
qualities of their
trunks. The canopy is
made up of finely
divided branches armed
with small thorns, and
compound leaves with 5
to 10 tiny leaflets.
Blue Palo Verde is
native to the American
southwest and northern
Mexico (including Baja
California) and is
widely distributed
across this range from
sea level to four
thousand feet. This
species is highly
adapted to desert
conditions, tolerating
high summer
temperatures, and is
cold hardy to 10 to 15
degrees. It is found
naturally along desert
washes and on hillsides
where soils are
reasonably developed and
where some summer soil
moisture is available.
In native settings Blue
Palo Verdes grow as
large shrubs, 25' to 35'
tall and as wide.
Its uses include: as
single large specimens
or small groupings as a
landscape focal point;
at project entries; near
monuments or signs; or
at tee boxes, greens and
along fairways in golf
courses. Its desert form
and character make it
ideal as a transition
tree between landscaped
areas and undisturbed
desert or as a theme
tree in large landscape
designs. They are also
use in streetscape and
perimeter planting in
commercial, residential
and municipal
landscapes.
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.
