WCN Dec e

ONE WAY YOU CAN TELL THAT IT'S ANT DAMAGE IS THAT THE ANTS
DON'T LIKE THE SKIN OF THE KERNEL. SO, IF ALL THE WHITE MEAT
PART OF A KERNEL IS EATEN OUT, AND THERE'S STILL REMNANTS OF
THE SKIN FROM THE SURFACE OF THE KERNEL, THAT'S ANT DAMAGE.
– DAVID HAVILAND, UCCE
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they need to dry, they need to be blown,
windrowed and then picked up. And
the issue is, from an ant management
standpoint, the longer the nuts are on
the tree, and the drier they are when
you shake the tree, the less time they
need on the ground before you can pick
them up,” Haviland said.
But the longer the nuts are left in
the tree, the longer they are exposed
to navel orangeworm. So growers are
juggling between harvesting the trees
as late as possible to minimize ant
damage and getting the nuts off the
tree as fast as possible to prevent naval
orangeworm damage.
“What ends up happening is growers
primarily deal with the ants by applying
baits, and then shaking the trees as
soon as possible,” Haviland said.
Shell Uniformity
Hard shell varieties are less susceptible
to ant damage than soft shell varieties.
“All varieties have split hulls, but
the integrity of the shells does change,”
Haviland said, adding the way the
almonds are managed during the year
can affect the integrity of the shell.
Haviland explains that if almonds
are really wet, then really dry, then
really wet, then really dry, there will be
periods of rapid hull expansion, and it
can impact the uniformity of the shell.
It’s similar to growing backyard tomatoes.
“If you forget to water them for
a couple of weeks, and then give them
tons of water, those tomatoes expand
really fast and split. The same can happen
with cherries close to harvest if you
get a rainstorm,” Haviland said, adding
uniform irrigation and growth equals a
more uniform shell.
Organic Management
There are organic baits, but they
aren’t as effective as conventional baits,
Haviland said.
“For organic growers, it really comes
down to getting the nuts off the ground
as fast as possible. Also, a lot of organic
growers, in order to help prevent damage
from navel orangeworm, tend to
grow more hard shell varieties because
they’re less susceptible to navel orangeworm.
That also makes those varieties
less susceptible to ant damage.”
Determining Damage
Taking annual samples at harvest is
important to determine the level of ant
damage.
“One way you can tell that it’s ant
damage is that the ants don’t like the
skin of the kernel. So, if all the white
meat part of a kernel is eaten out,
and there’s still remnants of the skin
from the surface of the kernel, that’s
ant damage,” Haviland said, adding
they will also leave behind a powdery
substance that is an indication of ant
damage.
Pros and Cons of Specific Baits
Baits fall into two main groups.
Clinch, Esteem, Extinguish are all applied
approximately two months before
harvest (May and June). The worker
ants take the bait into the colony, it’s
fed to the queens and the queens become
sterile and/or die.
“This has been a standard practice
for a couple of decades,” Haviland said.
There is also a newer bait called
Altrevin. Altrevin works much faster,
but doesn’t have the residual effect of
the other baits.
“Growers that want to use Altrevin
will typically apply it within a couple of
weeks of harvest,” Haviland said.
The advantage of first three baits are
that they are inexpensive and applied
earlier in the season when typically
labor and equipment are available to
make those applications.
In comparison, an application of
Altrevin must be made just prior to
harvest when growers are in harvest
preparation and equipment may be tied
up with hull split sprays, mowing and
other ground preparations.
“There’s just a lot of things going on
at that time, where it’s nice to just say
in May or June that you’ve checked the
box, you’ve put out your baits and ants
won’t be a problem,” Haviland said.
But Altrevin has the advantage that
growers can monitor ant populations
and decide whether or not to treat two
weeks before harvest.
“It’s easier to react to the popula-
86 West Coast Nut December 2021