Organic Farmer Aug/Sept 2019

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samples) to track insect and damage
activities in the orchard and use this
information for in-season management.
The second major group of the insect
pests of concern is true bugs, mainly
leaffooted bug and a few species of the
stink bugs. These bugs have piercing
and sucking type (i.e., straw-like)
mouthparts and attack on developing
fruits. The feeding can cause a
substantial crop loss due to the nut
abortion early in the season and by
producing defect kernels at harvest
from mid-to-late season infestations.
Visual and trap-based monitoring of
the orchard regularly is essential to
detect bugs while they are moving into
the orchard from their overwintering
habitat early in the season. Plant and
stink bugs are difficult to control with
other practices except for the use of
broad-spectrum insecticides, and the
insecticides for organic use are not
very effective. General practice is to
apply pyrethrin-based insecticide, some
neem-based products, and this is the
area where there has been a significant
lag in terms of efficacy trials looking
at various insecticides for organic
use. Now, with the spread of the new
invasive stink bug species, brown
marmorated stink bug (BMSB) to crops
including damage to almond, there is a
desperate need for exploring some new
tools to control these bugs, especially in
organic production systems.
The third group of the arthropod pests
of the nut crops is spider mites. Spider
mites can effectively be controlled by
following the IPM practices in nut crop
orchards. Predatory mites and other
mite predators are active along with
spider mites in nut crop orchards. In
recent years, we have seen the surge
of six-spotted thrips and spider mite
destroyer beetle (i.e., Stethorus beetle),
both are effective predators, throughout
the Central Valley almond orchards,
and there have been examples that these
predators keeping mite population
under control in San Joaquin Valley
almond orchards. The caveat is that
growers and PCAs need to follow the
available monitoring and sampling
practices to understand the phenology
of the pest and predators, plus apply
the pest management program that is
not disruptive to these natural enemies.
Some cultural practices such as a drier
orchard environment can foster the
mite population, and practices that
reduce these conditions can reduce the
mite population. If needed, oil-based
miticides are effective and available to
use against mites should they reach the
thresholds. See a recent article about
mite control in organic production by
David Haviland, UCCE Kern (https://
bit.ly/31IJIAu).
The fourth group of insects is relatively
small sucking insect pests such as
aphids, mealybugs, scale insects. These
insects often have a robust natural
enemy complex in the orchard. In most
cases, they are capable of keeping the
population below the threshold levels. It
is also critical to remember; these pestnatural
enemy interactions are often
in a delicate balance situation which is
likely to be disrupted easily when using
broad-spectrum insecticide, especially
early in the season. Conducting regular
monitoring and sampling is highly
recommended to track the insect pest,
and predator dynamics population
in orchards. UCIPM has published
protocols for sampling scale and mites
in almond, walnut, pistachio during
the dormant season. The sampling can
be done by examining pest and natural
enemy presence and abundance in
fruit spurs, scaffolds, branches, fruiting
woods, and recording the abundance.
Almond: http://ipm.ucanr.edu/PMG/
C003/m003dcdmtspursmpl.html
Walnut: https://www2.ipm.ucanr.
edu/agriculture/walnut/Dormant-
Monitoring/
Pistachio: https://www2.ipm.ucanr.edu/
agriculture/pistachio/Soft-Scales/
For San Jose scale and non-webspinning
mites (brown and European red mites)
infestation in almonds can be treated
with the dormant oil (6-8 gallons/acre)
during the delayed dormant timing
Summary
Although demand and acreage for
organic crops have been rising, effective
tools for organic pest management
are limited. Organic growers need to
deploy available pest management
tools strategically that includes
utilizing monitoring tools, cultural
practices, biological control, any other
preventative options available as much
Adult spider mite destroyer, Stethorus picipes,
feeding on a mite. Photo by Jack Kelly Clark,
courtesy University of California Statewide IPM
Program.
Photo by Jack Kelly Clark, courtesy University of
California Statewide IPM.
Sticky panel trap with BMSB lure installed in an
almond orchard to monitor BMSB activity.
as feasible. Organic growers should
not solely rely on insecticides as they
are costly, and the majority of them
may not be very effective compared
to the chemical insecticides used in
conventional orchards.
Comments about this article? We want
to hear from you. Feel free to email us at
article@jcsmarketinginc.com
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Organic Farmer August/September 2019