WCN Dec e

Larvae can overwinter in mummies left
on almond trees after harvest (photo by V.
Boyd.)
The lack of availability and increasing cost of polling crews have prompted many growers to
rely solely on mechanical mummy removal (photo by V. Boyd.)
Continued from Page 9
definitely pyrethroid resistance,” he said.
Application timing is critical as the
hulls split and the nuts become susceptible
to NOW egg laying.
Machado said growers should time
hull split sprays based on the crop stage,
not the moth flight. Where they may get
into trouble is not noticing the nuts in
the tree tops that typically split before
those at eye level.
“They need to be watching the tops of
the trees, whether that’s with a pruning
tower or long hook,” Machado said. “If
you look where the nuts are in the canopy,
they’re in the tops of the trees.”
“Timely” Harvest
While some talk about an early
harvest to possibly avoid the third NOW
flight, Machado prefers the term “timely
harvest.”
“What’s the goal?” he asked. Is the
crop going for meats or for in-shell,
since the two end uses prompt different
harvest timing.
Even then, it’s a balancing act. Ideally
for the meat market, Extension recommends
shaking when 100% of the nuts
are one-half to two-thirds of the way
split and the hull is still green, known as
stage “d.” With some varieties, growers
have found that harvesting at stage “c,”
when the hull split is 0.25 to 0.5 inch,
allows for a cleaner shake.
Harvest significantly earlier, and resulting
higher moisture levels will mean
the nuts have to sit on the ground longer
to dry. This makes them potentially
susceptible to additional ant damage,
Machado said. Going too early also may
mean the brown kernel skin hasn’t set
adequately, and you get more “peelers.”
On the other hand, if you let the nuts
dry for a prolonged period on the tree,
you expose them to an increased egg
laying potential from the third NOW
flight. The hulls also cup and become
tough, making them more difficult to
remove.
For the in-shell market, Machado
said growers should wait until the hulls
butterfly before they harvest. Leaving
the nuts on the tree longer also exposes
them potentially to more NOW egg
laying. If the orchard was managed
with high fertility, toxins from hull rot
also could build up with later harvest,
creating more stick-tights.
To determine how well their NOW
program worked during the season,
Rijal said growers shouldn’t just rely on
handlers’ grade sheets. In addition, they
should collect field samples at harvest
because up to half of damaged nuts are
left in the orchard and aren’t reflected
in the reports.
“Take multiple samples of 500 to
1,000 nuts representing the orchard and
crack the nuts out,” he said. “It helps to
know what’s going on and also look at
the history of the orchard.”
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10 West Coast Nut December 2021