2001 Vol. 45, Number 1
Contributing editor to the OOQ
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from past issues
eucalyptus trees in Phoenix, Arizona, were dying fast. And
it was Jeff Walton’s job as an arborist to find out why.
After examining the trees and researching plant diseases,
he identified the culprit: the eucalyptuses were infested
with a fungus. Jeff injected the trees with a specially
formulated fungicide and prescribed a watering regimen. The
trees survived, together with the shade they gave the
"Arborists are really tree doctors," says Jeff.
As tree doctors, arborists diagnose and treat tree diseases,
nutrient deficiencies, and structural problems. "Trees
are living organisms," he says. "They are
constantly growing and changing."
Working as a consultant for a tree care company, Jeff helps
people understand and care for their trees. "One of the
things I like most is education—explaining how the anatomy
of a tree works, how diseases affect trees, and how a tree’s
immune system functions," he says. "I like
convincing people that their trees are living and growing
and need to be kept healthy."
Jeff drives to customers’ houses and examines their
trees. He checks the bark for signs of decay or damage.
Then, he checks the leaves for abnormal changes in color or
texture. Sometimes, he removes dirt at the base of the tree
to examine the root structure. Like most arborists, he uses
binoculars to inspect the upper branches of a tree or climbs
into the canopy of branches for a closer look.
When an illness is hard to diagnose, Jeff takes tissue
samples, snipping off leaves or small branches. He sends the
samples to arborist specialists for analysis.
If Jeff finds viruses, bacteria, fungi, or harmful
insects, he recommends a course of action. He might spray
the tree with pesticide or fungicide or inject medicine into
its bark. After treatment, he might prescribe a special
watering or fertilizer regimen, as he did in the case of the
dying Arizona eucalyptuses.
Often, he cuts diseased or infested branches off the tree to
save the others, a process called pruning. He also prunes
branches that rub together and those that are not well
supported by the rest of the tree. Pruning a tree correctly
takes skill. Arborists climb onto a tree’s branches using
ropes and hanging seats called climbing saddles. They
carefully remove branches with chainsaws, shears, and tiny
clippers. If a branch is diseased, arborists sometimes dip
their tools in disinfectant before cutting another branch to
prevent the spread of infection.
Jeff, like all arborists, uses mathematics to analyze a
tree’s structure before he decides which branches to cut.
"We use equations to decide how structurally sound a
tree is," says Jeff. "We measure the tree’s
circumference, and we can figure out a tree’s height
without climbing it." Some arborists use computer
programs to calculate the forces and weights within a tree.
A tree’s structure can be a matter of life and death
for the people who live near it. Weak, diseased, or
unsupported branches can crack and fall, crushing cars,
houses, or people beneath them.
Despite all the treatments available, some trees cannot be
saved. "People don’t look up at their trees often
enough," Jeff explains. "It’s not until a tree
is screaming for attention that most people notice there’s
a problem. We can’t always save trees that are already
Removing a dead or dying tree can be tricky. To remove a
poplar tree from a customer’s yard, for example, Jeff
needs a climbing saddle, ropes, chains, and a 200-ton crane—along
with the help of other arborists and landscape workers.
Tree care and removal is dangerous work. While balancing
in climbing saddles high above the ground, most arborists
use chainsaws to cut branches. Avoiding injuries takes
practice and training.
Even without a traumatic injury, arbor care can be
strenuous. "You’re carrying heavy wood," Jeff
says of downed trees and branches. "This work can be
hard on your back."
Not every arborist’s job is as physically demanding,
though. Some arborists help clients decide which trees to
buy and where to plant them. Conditions vary from region to
region and even from one part of a backyard to another.
Arborists understand which trees will thrive in which
Other arborists preserve trees growing on construction
sites. They mark where roots begin and design temporary
enclosures to protect them during building. An arborist can
do this kind of work without ever climbing a tree.
The Bureau of Labor Statistics does not collect
employment data on arborists. But according to the
International Society of Arboriculture, there are more than
12,000 certified arborists in the United States and
thousands more who aren’t certified.
Most arborists work for tree care companies. Others work for
State and local governments, caring for trees on roadsides
and other public properties. And some work for themselves as
Earnings increase with experience and responsibility.
Ground workers, who chop and carry away fallen branches,
earned an average of $9.50 an hour in 1999, according to a
survey by the National Arborist Association. Climbers earned
an hourly average of $13, and crew leaders averaged $15.
Arborists who diagnose and treat specialty trees can earn
Still, like most arborists, Jeff didn’t choose his career for the money—although he says the field can be
financially rewarding to people who are good at their jobs.
Drawn to his work by a love of the outdoors, Jeff changed
his career path to work with nature. "I was in college
studying for a business degree, but at the same time I was
working at a landscaping company," he says. "I
realized that with a business degree I might end up in a
cubicle, watching the outdoors from a little window. If I
worked in landscaping, I could be outside all day in the
natural environment." He stopped studying business and
started working full time at a plant nursery.
Over time, Jeff’s interest in trees grew. He took
classes in tree anatomy, physiology, and disease treatment
while working at the plant nursery. After gaining more than
3 years of field experience, he took the Society’s
certification exam and became a certified arborist. He still
takes classes to maintain his certification and to keep up
with scientific advances in tree care. "We need people
who are curious. There are always new things to learn about
trees," he says.
Some arborists combine coursework with experience, as
Jeff did, to enter the occupation. Others enroll in formal
degree programs, earning an associate or bachelor’s degree
in horticulture, botany, or forestry. Still others continue
their education, earning a master’s or doctoral degree.
Those with advanced degrees sometimes become researchers or
expert witnesses in court cases involving trees.
Hands-on tree work is still the kind of arbor care Jeff
likes best. "It’s an honor to work with these
majestic living organisms," he says. "To be able
to understand what makes them strong and healthy is amazing.