March 2020 - 31

Fig. 2 Electron Micrograph of 3% CNC film.
Fig. 3. Freeze tolerance of 'Benton' sweet cherry from large scale trial buds 6 days
post-application. Graphic: Washington State University
This process makes it a renewable and
sustainable product. The material's
nanostructure gives it unique physical and
chemical properties. Most importantly,
it has a very low thermal conductivity,
meaning it holds in heat. Our team at
WSU has developed a novel method
for suspending these materials into a
sprayable aqueous dispersion (Fig. 1).
We have demonstrated that using
electrostatic application technology,
these dispersions form a thin (ca.
25µm-40µm; Fig. 2) and durable
insulating film around the surface of
the buds. When coated, the bud is
slower to lose heat into the environment
than untreated buds, improving their
resistance to cold temperatures.
Since 2018, we have been
investigating the protective effects
of CNC coatings in apple, grape and
sweet cherry. Our initial small plot
work revealed significant improvement
in cold tolerance, with treated flower
buds having up to 6˚ F improved
tolerance. More recently we have
compared cold damage of trees treated
with CNC using commerciallyavailable
electrostatic sprayers (On
Target Spray Systems) to damage in
untreated trees. We again documented
significant improvements in cold
tolerance - treatment of about 3%
CNC in a 'Benton' orchard reduced
the temperature of first damage (i.e.,
flower death) by about 8˚ F (Fig. 3). The
protection can last at least seven days
post-application, but since the material
is water-soluble, precipitation will
reduce/eliminate any protection.
In addition to the protection given to
dormant buds, CNC coatings can also
protect buds during anthesis when floral
tissue is most sensitive. Dispersions can
be applied as late as the popcorn flower
stage and can add as much as 5.4˚ F
protection to the developing floral tissues.
However, this protection appears to be
short-lived, lasting about 48 hours at early
stages of flowering (e.g., popcorn), and
CNC treatments appear to be ineffective
once the flowers are fully open.
This emerging data on CNC's
effectiveness for improving bud hardiness
suggest it may be a promising new
advancement as a freeze prevention tool.
The authors received financial
support for this research from USDANIFA
and the Washington Tree Fruit
Research Commission. FGN
®
Why is Calcium so important?
Form. Taken up as ionic
Ca2+, calcium is essential
for cell division and
development of the active
root and shoot tips. Calcium
plays a central role in plant
structure both above and
below ground.
Function. Calcium is vital
for activating enzymes
that promote growth and
stimulate immune system
responses. In addition,
calcium acts as a binding
agent that is essential to the
structure of stems, roots
and fruits. Low calcium
status results in low vigor,
slow development of shoot
and root, reduced nutrient
recovery and increased
abiotic stress.
Symptoms. Low Calcium
status affects rapidly
expanding tissue such
as new leaves, roots and
developing fruit. Meristems
fail to expand, and growing
points become necrotic. Leaf
scorch, tip burn and blossom
end rot are classic symptoms
of low Calcium status, all
of which are worse during
conditions that promote
rapid growth.
Significance. As mobility
within the plant is very low,
calcium demand can readily
exceed supply, creating
stress which results in
restricted leaf, root and fruit
development. As calcium
is taken up by a very small
fraction of new roots,
anything that restricts root
development will affect
calcium uptake.
Actions. Check soil calcium
status and make corrections
if necessary. Maintain
plant phosphorous and
zinc level to optimize root
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heat or moisture stress.
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At OMEX® we take plant health
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FGN | MARCH 2020 | 31
http://www.omexusa.com
March 2020

Table of Contents for the Digital Edition of March 2020
