IN YOUR ORCHARD
suitable for drainage in rainy weather and that is not
near equipment or fuel storage. Stockpiles should be
oriented in a north-south direction to aid in drying and
covered with white-on-black tarps. Monitor humidity
and open the tarp when appropriate to reduce
condensation and mold formation. Also monitor and
treat for insect, bird, and rodent pests. If rain threatens,
ensure piles are covered. Finally, be aware that
stockpiles are a potential fire hazard.
Stockpiles should be fumigated to reduce insect
infestation. NOW is an excellent storage pest and can
survive in stockpile conditions. Furthermore, this pest
can continue to feed and reproduce within stockpiles,
increasing damage as well as aflatoxin risk. In 2018, a
local farmer refused to fumigate their stockpiles, only
to see an increase of NOW damage from earlier
submitted loads (he went from 2.3 percent to 9 percent).
Although time consuming, fumigation is critical in killing
larvae and eggs, reducing damage.
Be wary of too much moisture in stockpiles. Studies
have shown that hull moisture above 14 percent and
a holding temperature greater than 120 degrees
Fahrenheit will increase the risk for concealed damage
and mold. If needed, delay harvest until nuts can dry.
If already in stockpiles, remove tarps during the day to
dry and cover at night. If harvesting in rainy conditions,
keep the nuts in the tree if possible to aid in drying. If
already on the ground, try to encourage drying
by removing leaves, twigs, and other material.
This may take several passes with the pick-up
machine or conditioner.
Postharvest Irrigation and Nutrition
The initiation of fruit bud formation occurs for most
almond varieties in mid-to-late August. Severe stress
imposed during this period can reduce floral bud count
and fertility in the following years. Trees should be
irrigated as soon as possible after harvest to reduce
stress. During this period, the tree is also building
nitrogen stores for the following year. Approximately
20 percent of the nitrogen budget should be applied
in the postharvest period. The rate may be reduced
if mid-July leaf samples were above 2.5 percent. No
more than 50 pounds of nitrogen should be applied,
however, as research has shown that the shorter days
and lower ETc demands limits the amount of nitrogen
uptake to about this much for a mid-August harvested
variety. Rates for later harvesting varieties should
be less. There probably is minimal value in applying
nitrogen after the beginning of October.
Hull Analysis for Boron
Boron is an important micronutrient for almonds. Boron
is critical for flower fertilization, as it is involved in
directing the germinating pollen tube. Deficiencies
lead to reduced nut set, and in severe cases, an
appearance of a “nonproductive symptom.” Within the
tree, boron deficiency can lead to gummy nuts in the
spring, dieback of small twigs and a “weeping branch”
look. Boron is also toxic at high concentrations. Boron
toxicity is often observed in areas with high soil boron
or in blocks irrigated with water containing boron.
Boron toxicity symptoms appear as gummy nuts that
may form “stick tights,” as well as gum exuding from
pruning wounds, bud and leaf scars, and spurs.
Critical threshold levels for boron hull values are as follows:
Hull Boron Level (PPM)
Deficiency
<80 PPM
Sufficient
100–160 PPM
Toxicity
>300 PPM
Kernels from trees with boron deficiency often have hardened
“gum” and are shriveled. By the time these symptoms occur,
moderate crop loss has occurred.
3 6
A L M O N D F A C T S
