16 CapitalPress.com
March 6, 2015
Cherry trees shrink along with labor pool
Diminutive trees
increase worker
efficiency
By MATEUSZ PERKOWSKI
Capital Press
Cherry trees in the North-
west are shrinking as growers
plant diminutive orchards in
anticipation of labor shortag-
es, experts say.
Traditional orchards, with
large trees planted at spacious
distances, are often getting
replaced with higher-density
“pedestrian” systems in which
most branches are within an
arm’s length, expediting func-
tions like pruning and har-
vesting.
A worker with both feet
on the ground can collect up
to 170 pounds of cherries per
hour, compared to 100 pounds
if he’s frequently moving and
climbing ladders, said Lynn
Long, extension horticulturist
at Oregon State University.
Matt Whiting
Lynn Long
“He’s increasing efficien-
cy, which means you need to
hire fewer pickers,” Long told
farmers at a recent OSU cher-
ry research symposium in The
Dalles, Ore.
Migrant workers are mov-
ing to other industries and the
cost of labor is rising, forc-
ing growers to think about
running their operations with
fewer people, he said.
Apart from easing access
to fruit and tree limbs, high-
er-density orchards offer uni-
formity — trees are trained to
grow similarly, reducing com-
plications and mistakes com-
pared to traditional orchards,
in which each tree is different,
Long said.
“It slows down that opera-
tion,” he said.
Farmers have multiple op-
tions for establishing pedestri-
an-style orchards. One popu-
lar option is the “Kym Green
Bush,” in which limbs are cut
back to form a compact struc-
ture with multiple “leaders.”
With the “upright fruiting
offshoot” technique, the tree
grows along a trellis with ver-
tical branches springing from
a largely horizontal trunk.
A new system that hasn’t
been adopted commercially
is the “super slender axe,” in
which a single central leader
produces lateral branches that
are cut back hard each year.
The fruiting wood remains
close to the trunk while large
shoot leaves develop on the
new limbs, resulting in high
quality cherries that are sim-
ple to pick, Long said. “You
don’t have to reach for them.
It doesn’t get any easier than
that to harvest cherries.”
Growers are able to quick-
ly achieve a healthy per-acre
yield with the system but it’s
expensive to establish, he
said. About 2,500 trees per
acre are planted with the super
slender axe system, compared
with 350-700 per acre with
the Kym Green Bush.
Farmers are concerned that
the transition to denser, “high
output” orchard systems will
be correlated with higher in-
puts, which can be mitigated
or prevented with automation,
said Matt Whiting, extension
specialist with Washington
State University.
Mechanical pruning, for
example, can greatly speed the
process though it does involve
some challenges, he said.
In one trial, a hedging ma-
chine was able to remove lat-
eral branches 12.5 times fast-
er than hand pruning but left
more wood on the tree.
“It’s not perfect, but it’s
not that bad,” Whiting said.
When mechanical pruning
was followed by a manual
“clean up” — cutting limbs
between trees and closer to
trunks — the process was
still 25 percent faster than just
hand pruning.
One possibility would be
to alternate mechanical prun-
ing one year with a combina-
tion of techniques the next, he
said.
Whiting and other re-
searchers recently completed
a five-year study of mecha-
nized harvesting, which was
funded with a $4 million
USDA grant.
By vibrating tree limbs
to knock cherries from their
stems, a mechanical harvester
prototype increased harvest
efficiency by 50-fold, he said.
With a “mechanically-as-
sisted” approach, in which a
modified reciprocating saw
vibrated limbs, cherries were
harvested four times faster
than hand-picking.
A commercial solution for
mechanized picking isn’t yet
available and some producers
worry that stemless cherries
won’t find a market, Whiting
said.
However, surveys indicate
that consumers don’t actually
prefer cherries still attached to
stems, he said.
Chelan Fresh, a marketing
company, is testing the waters
with packaged cups of cher-
ries that are convenient to eat,
Whiting said.
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