WCN November 2019

to control soilborne pests. Biosolarization
can promote inactivation of a broad
range of soil pests that are relevant to
a variety of crops, including almond
orchards. In the case of orchards, some
of these pests—parasitic nematodes and
other pathogens—feed on roots and can
kill or stunt almond saplings. This is
known as “replant disease” and can affect
one third of California almond acreage if
left untreated3.
Traditional solarization has been used
as a pest management tool for decades.
Simply covering moist soil with clear
plastic during the hot summer months
can increase soil temperatures above
120˚F, more than enough to kill many
pests. Unfortunately, solarization typically
underperforms in orchards and
other cropping systems as soil heating is
limited to shallow depths and is critically
dependent on the weather.
Organic matter such as almond hulls
and shells can potentially solve this
problem. By amending soil with organic
matter before solarization, biosolarization
may promote disinfestation to greater
depths than traditional solarization,
shorten the treatment duration, and
guard against unpredictable performance
owing to the weather and variable solar
heating.
Biosolarization using hulls and shells
presents multiple benefits to California
agricultural soils by:
• Taking advantage of local and abundant
biomass to promote zero- waste crop
production.
• Adding organic matter to the soil
to promote soil health and water
retention in the root zone.
• Providing more environmentally
friendly pest management than
conventional pesticides.
Why does it work? Biosolarization
uses multiple modes of action that act
together to kill soil pests. In addition to
the soil heating, microorganisms in the
soil consume and degrade the amended
organic matter. In doing so, they convert
the sugars from hulls and shells into
organic acids—natural “biopesticides”
that can quickly disperse into deeper
soil layers. These compounds are toxic
to many pests but are relatively safe for
humans and benign soil microbes.
Depending on the temperature, biosolarization
can eliminate pests in 8-10 days.
Soil Health Benefits
Recycling hulls and shells into the
soil can deliver other benefits to soil
health and crop production. For example,
adding organic matter to soil increases
water infiltration into soil along with the
water holding capacity of soil, which can
decrease runoff of rain water.
Adding these materials can also
improve soil fertility. Almond hulls
and shells naturally contain nitrogen
Continued on Page 10
Prepare your Nut Trees for Next Season with
the Westbridge Post-Harvest Program
ORGANIC
Contains Auxiliary Soil & Plant Substances
®
®
ORGANIC
Plant Nutrients
The Westbridge Post-Harvest Program is designed to increase root
growth and improve nutrient uptake of fall fertilizers, preparing
trees for next year’s growing season.
Apply a soil or foliar application
within 30 days after harvest to:
• Improve winter hardiness
• Increase root growth and
perennial wood
• Improve fruit bud vigor, which
can lead to reduced alternate bearing.
Program Includes:
• Organic TRIGGRR ®
*When plants are in need of more nitrogen, Organic BioLink® Cal-N
can be substituted for Organic BioLInk® Cal-Plus 7%
• Organic BioLink ® Cal-Plus 7%*
• Organic BioLink ® 3-3-3 Fertilizer
• Organic BioLink ® Micronutrients
(800) 876-2767
www.westbridge.com
®
November 2019
www.wcngg.com
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