IN YOUR ORCHARD
34
Almond Facts
JULY | AUGUST 2017
DAVID DOLL, UCCE Nut Crop Pomology Farm Advisor, Merced County
Time To Consider
Harvest will be closer to “normal” this year. This season is later than the last few years due to the
cooler weather experienced shortly after bloom. Harvest timing will be tricky to determine due to the
long duration of bloom, which usually indicates that the nuts will ripen over a longer period of time.
Irrigation Management
With the exception of drying down the orchard for
harvest practices, irrigation during the period of hull-split
to harvest should be as close to full evapotranspiration
(ET
c
) as possible. Kernel weight is still accumulating and
continues until the abscission layer between the peduncle
and hull forms. Adequate, (but not excessive) moisture
must be available through hull-split, as hulls must be
turgid to properly split. Water stress can change the onset
of hull-split and ripening, cause stick-tights, reduce kernel
weights, and cause shriveling or “texturing.” Excessive
moisture, however, can delay harvest and increase the
incidence of hull rot.
Harvest Timing
Timing of harvest is always tricky. Growers must balance
between harvesting early and having a longer dry time
on the ground and a greater chance of ant damage, or
harvesting later and having a greater chance of navel
orangeworm infestation (NOW). In years in which NOW
pressure is greater than normal – such as this year – an
earlier timed harvest should be considered. Trees should
be shaken as soon as a few test trees shake clean. Be
careful on shaking too green, as longer shaking time per
tree can damage tree trunks. This “barking” of trees
often creates wounds that are susceptible to fungal wood
pathogens such as
Ceratocystis
. Once the nuts are on the
ground, windrowing and pickup should occur in a timely
process to reduce ant damage.
Harvest Sample
Taking a harvest sample is simple, but time consuming. It
should be considered because the amount of insect damage
can be masked by the handling that occurs during sweeping,
pickup, and processing. Our trial data has found that as
much as 4% more damage can be found in harvest samples
than what was indicated in the processor report. In other
words, when we found an estimated 5% damage/reject level
in the harvest sample, the processor indicated a 1% rejection
level. The 4% discrepancy is most likely due to damaged nuts
lost during the harvesting process (i.e. sweeping, pick-up, and
removed during hulling and/or shelling). This is still lost crop
even though it isn’t detected in the processer reports.
Another reason for performing a harvest sample is to
identify the type of damage that occurred. For example,
ant damage often does not show up in the final grade
because the chewed kernels are often blown out the back
of the pick-up machine and are not present in the delivery
sample taken at the receiving station. Gummy nuts due to
nutrient deficiencies, feeding damage, or other conditions
are also lumped together as rejects on grower statements.
Growers should also consider requesting a breakdown
of the causes of the reject damage in their deliveries
by contacting their huller/sheller or
Blue Diamond
Field
Supervisor. That information will then be printed on
the statement growers receive along with their Delivery
Advance Payment.
Collecting a harvest sample is easy. In each block of
concern, collect 500 nuts from the ground after shaking
and place them in a paper bag. Two samples of 250, or 4
samples of 125 nuts from differing areas of the block can
also be collected, but try to keep the total number of nuts
per block at 500. Store the bags in a freezer until they can
be cracked out. This may be several weeks after harvest.
A small navel orangeworm (NOW) larvae
crawling on the surface of a nut. NOW will
feed on the nut, decreasing crop yield and
quality while increasing the risk of aflatoxin.
