May 5, 2017
CapitalPress.com
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11
California
Shorter, ‘ladderless’ peach, nectarine orchards taking off
By TIM HEARDEN
Capital Press
PARLIER, Calif. — As la-
bor shortages intensify, grow-
ers in California are switching
to shorter peach and nectarine
trees to eliminate the need for
ladders.
University of California
scientists have developed
“semi-dwarfing” rootstocks
in various densities to create
“ladderless” orchards, en-
abling laborers to save time
by picking from the ground
instead of having to move and
position ladders during har-
vest.
Growers have planted
about 1,000 acres of the new
rootstocks in the past three
years, said Kevin Day, a UC
Cooperative Extension farm
adviser in Tulare County.
Tim Hearden/Capital Press
University of California Cooperative Extension pomology adviser
Kevin Day stands in a “ladderless” peach orchard at the UC’s Ke-
arney Agricultural Research and Extension Center in Parlier, Calif.
He said growers have planted about 1,000 acres of the labor-sav-
ing orchards in the last three years.
“They’re being planted by
small growers and large grow-
ers,” Day said. “They just real-
ly like this concept.”
Day worked with UC-Da-
vis plant physiology professor
Ted DeJong in developing the
rootstocks, using a four-acre
plot at the Kearney Agricul-
tural Research and Extension
Center in Parlier. Their mis-
sion was to test whether short-
er peach and nectarine trees
could reduce labor and insur-
ance costs without sacrificing
fruit quality and yield.
Day said he’s seen la-
bor cost savings of between
35 and 40 percent in tests of
semi-dwarfing rootstocks so
far. Moreover, the use of lad-
ders in conventional orchards
is why peach and nectarine
growers pay about 40 percent
more for workers’ compensa-
tion insurance than growers
who work with shorter crops
such as grapes, the UC has ex-
plained.
“Also, what people don’t
realize is it takes skill to posi-
tion a ladder,” Day said, noting
a worker needs to be able to
pick as much fruit as possible
from one spot.
“From a sociological per-
spective, as labor becomes
more scarce, we’re seeing
more and more women in
crews, and ladders are heavy,”
he said. “Women can pick just
as fast as men, but moving the
ladder takes its toll.”
Conventional peach and
nectarine trees grow to about
13 feet tall, requiring the lad-
ders to harvest the fruit. La-
borers spend about half their
time setting up, climbing and
moving the ladders.
Developed by breeders at
UC-Davis, the new rootstocks
produce trees that grow to 7 or
8 feet tall.
The trial at Kearney is part
of a larger experiment on best
practices for the fruit trees. The
researchers have been compar-
ing yields from a conventional
orchard with those of shorter
trees that have been minimally
pruned, made use of pressure
chambers to determine water
needs and been treated with
compost and nitrogen sprays
to minimize nutrient leaching
into groundwater.
The scientists found the
shorter trees to be more pro-
ductive, as their fruit quality
overall is equivalent to that
of the top half of larger trees,
while lower fruit in conven-
tional trees tends to be light-
starved and of poorer quality,
Day said.
Day expects more of the
shorter trees to be put in as
growers change out their or-
chards. “Change takes time,”
he said.
HLB infections in commercial Calif. citrus inevitable, researcher says
By TIM HEARDEN
Capital Press
PARLIER, Calif. — A cit-
rus pest researcher believes
huanglongbing infections in
California’s commercial cit-
rus orchards are inevitable,
and she believes they’ll force
significant changes in the in-
dustry in the next decade.
Entomology
specialist
Beth Grafton-Cardwell, direc-
tor of the University of Cali-
fornia’s Lindcove Research
and Extension Center in Ex-
eter, says she anticipates “lots
of citrus removal” in coming
years as trees start dying.
“I think this is going to
radically affect where and
how we grow citrus,” Graf-
ton-Cardwell said, adding
the disease may cause a shift
away from navels and toward
more resistant Mandarin or-
ange trees.
Growers may have to ac-
cept shorter lifespans of trees,
too, she said. While the av-
erage navel tree can live 80
years, growers in China ex-
pect their trees to live an aver-
age of 15 years, she said.
“This disease is hard to
control,” she said. “Once
it gets going, it’s going to
change the landscape in Cal-
ifornia.”
Grafton-Cardwell said part
of her job is to help grow-
ers determine how best to
Citrus Pest & Disease Prevention
Program
Tim Hearden/Capital Press
University of California citrus
entomologist Beth Graf-
ton-Cardwell works in a lab at
the UC’s Kearney Agricultural
Research and Extension Cen-
ter in Parlier, Calif. She said it
is inevitable that huanglongbing
will find its way into commercial
citrus trees in California.
respond to the Asian citrus
psyllid, which can carry huan-
glongbing, also known as cit-
rus greening.
First discovered in the
United States in 2005, huan-
glongbing has devastated the
citrus industry in Florida,
Georgia, Louisiana, South
Carolina and Texas, causing
an average loss of 7,513 jobs
per year and costing growers
nearly $3 billion in revenue,
the University of Florida es-
timates.
Huanglongbing has caused
Huanglongbing, also known as
citrus greening, makes the fruit
unusable.
a 75 percent decline in Flori-
da’s $9 billion citrus industry
and has led to full or partial
psyllid quarantines in 15
states and territories, includ-
ing California.
The disease has yet to be
found in any of California’s
commercial groves, but it has
killed 54 residential citrus
trees in Southern California,
prompting the state to first
impose and then strengthen
a quarantine that now covers
about one-third of California.
“Everything we can do to
slow that spread will buy time
for the researchers,” Graf-
ton-Cardwell said. “We’re
hoping that Florida comes up
with a cure because they have
the disease and they’re study-
ing it.”
The problem is that sam-
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pling methods “are not as ef-
ficient as they could be,” so
infections could occur in trees
long before they’re detected,
she said. In the meantime, the
psyllid is “very effective” at
moving the disease, she said.
“HLB has a long latent
period,” said Ali Pourreza, a
UC Cooperative Extension
agricultural engineering ad-
viser. “Symptoms may show
up in a month, or it could be
a year. For good management,
we need to detect it early. An
infected tree is the source of
bacteria that can infect an en-
tire orchard.”
Researchers are looking
for ways to detect the dis-
ease in trees before symp-
toms appear, including by
training dogs to identify in-
fected trees by differences in
odor, Grafton-Cardwell said.
Pourreza is working on a
sensor that could detect huan-
glongbing early. He said he
envisions a tool that would be
inexpensive for growers —
perhaps even a smart phone
application.
The USDA has spent more
than $400 million since 2009
to address huanglongbing.
California’s citrus indus-
try has devoted $15 million
toward HLB research and
education, including $8 mil-
lion from the grower-funded
California Citrus Research
Foundation to construct a
biosecurity Level 3 lab near
UC-Riverside that should be
operational this fall.
Among the many research
efforts, the USDA’s Animal
and Plant Health Inspection
Service is taking comments
through May 10 as it prepares
an environmental impact
statement on planned field tri-
als of a genetically engineered
virus that could make trees re-
sistant to huanglongbing.
Grafton-Cardwell urges
growers to be proactive in us-
ing best practices to prevent
the spread of the psyllid, and
she tries to remain optimistic.
She notes that citrus crops in
the San Joaquin Valley may
have a better chance of sur-
vival than on the coast, be-
cause huanglongbing is sensi-
tive to extreme heat and cold.
But she knows the industry
is going to change, she said.
“It makes me sad every
day when I drive into Lind-
cove and see how beautiful
the trees are,” she said.
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