WCN April 2019

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of the buds for the next year, and is
progressive and accumulative over time,”
Fulton stated.
One of the end results from the study
was more research focused on early
season water management, he added.
The majority of water used in a
walnut orchard occurs from late June
through September.
“The important thing is that through
the relatively low period of water, from
early April through May, it is something
to be careful about to not be too aggressive
with water,” Fulton explained.
Two general concerns Fulton said
he hears in conversations throughout
the industry about early season water
management is being too aggressive
due to a concern for loss of deep soil
moisture, and the flip side of being too
cautious, delaying start with a concern
for tree loss.
“There is a line of thought, the
concept that with very aggressive
early season irrigation, you get the
tree growing so vigorously, so vegetative,
that they are not fruiting-up
as well,” Fulton said. “These are some
of the thoughts and concerns that
keep us working on early season water
management.”
A current long-term study and replicated
trial is taking place in the Crain
Orchards in Tehama County on manipulating
the start of irrigation season to
learn about impacts. The study involves
Chandler/Paradox trees in Columbia
silt loam and Columbia fine sandy loam.
Researchers are using pressure
chambers as their tool to establish
thresholds to determine when best to
start irrigation.
Summary points Fulton shared
on this trial are as follows:
If tree loss is of concern, delaying
the start of irrigation may provide a
healthier root environment without
significantly impacting other production
aspects.
Managed delays at the start of irrigation
did not result in more tree water
tress late season.
Positive responses in edible yield and
kernel color which influence nut value
along with water/energy savings may
help optimize returns to management
by delaying the start of the irrigation
season.
There is more opportunity to benefit
from early season delays in irrigation
than mid and late season water deficits
in walnut.
Future Research
Fulton said one area of future
research includes timing and extent of
Photo courtesy of Allan Fulton.
Future Research
Development and delivery of real-time applied
water, ETa, soil moisture and plant stress
information is underway and progressing.
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West Coast Nut April 2019