TIME TO CONSIDER
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Almond Facts
MARCH | APRIL 2016
Time To Consider
DAVID DOLL, UCCE Nut Crop Pomology Advisor
The spring time months of March and April present many challenges in managing almonds.
Irrigation, nutrient applications, disease management, and weed and insect control begin during this
period and are critical for developing a successful crop.
Spring-time Nitrogen
Management
Nitrogen applications tend to begin in mid to late March
for many operations. New nitrogen regulations require a
crop estimate in order to determine the seasonal amount
of nitrogen to apply. Crop removal studies have indicated
that around 65 pounds of nitrogen are removed with
every 1000 kernel pounds of harvest. Taking into account
nitrogen application inefficiencies, 85 pounds of nitrogen
must be applied to replace the removed amount.
Further research has indicated that multiple applications
of nitrogen should be made through the season with 80
percent of the total budget being applied prior to kernel fill
and the remaining 20 percent applied in the postharvest
period. Spring applications should be split to reduce the
potential of plant toxicity and leaching from spring rains
or over-irrigation. A good plan for a sandy loam or finer
soil would be 20-30-30-20 for mid-March, mid-April, mid-
May, and the postharvest period, respectively. In coarser
or soils with lower water holding capacities, smaller, more
frequent applications should be applied. Keep in mind
that if reducing water applications due to water shortages,
nitrogen applications should also be reduced.
Pest and disease considerations
for March/April
Disease concerns tend to run high in the spring as rains
may provide environmental conditions conducive for
infection. Sprays for shot-hole, anthracnose, jacket rot
and bacterial spot should be based on rainfall events.
Summer diseases of rust and scab, however, may still be
problematic and may require a treatment even in dry
spring conditions. Treatment timings for scab is two to five
weeks post petal fall, and five weeks post petal fall or later
for rust.
Anthracnose and bacterial spot proliferate in warm, rainy
weather and may require multiple treatments prior to
rainfall events. Bacterial spot treatments involve copper
and mancozeb treatments and should be considered in
orchards that have a history of disease. Please discuss
the usage of copper with your PCA or Farm Advisor as
almonds are sensitive to this element. Orchard history,
cultivar and irrigation systems should be factors in
determining the need for treatment. More information
can be found at the UCIPM website or in the January/
February
Time to Consider
column’s inserts.
Insect concerns include San Jose Scale (SJS), Peach Twig
Borer (PTB) and Leaf-footed Plant Bug (LPB). With the
warmer spring, male emergence for SJS and the biofix
for PTB will be earlier. Therefore, the traditional “May
Spray” timing may also be earlier. Timing of a growth
regulator for SJS control should be 400 DD after the
male flight. A spring treatment for PTB should be made
400-500 DD after the biofix. Keep in mind that the PTB
timing often overlaps with the spring flight of NOW. If
timed properly, this spray could provide early season
control for both pests.
LPB is erratic and hard to predict. Research does suggest
that over-wintering populations are reduced by below
freezing temperatures. In years with mild winters, such as
this past year, populations tend to be higher. Sprays should
be timed once adults are first detected, not once damage
occurs. Damaged nuts do not show symptoms for several
days to weeks after initial feeding.
Please keep in mind that there are more pests that affect
almonds during this time period. More information can
be found at
.
Weed control
Most spring time weed control programs are reliant on
post-emergent herbicides, particularly glyphosate. These
products should be properly selected to provide control
of the “escaped” weeds from the winter pre-emergent
program. Over the past several years, however, we have
seen an increase in summer emerging weeds that are
either glyphosate-resistant or have variably control with
this herbicide (e.g. lambsquarter, threespike goosegrass,
and junglerice). If present, alternative broadspectrum
“burn-down” products such as glufosinate or paraquat are
