WCN_Oct18_Final_e

WINTER SANITATION
Protect Yourself from NOW
By: Cecilia Parsons | Associate Editor
As the 2018 pistachio harvest comes
to an end, it is time for growers and
managers to take a look at improving
their orchard sanitation practices.
Shaking mummy nuts from trees,
blowing mummies or trash nuts out of
tree crotches and cracks; ruts and rodent
holes, and into the middle of the rows
where the nuts can be destroyed is a
first step in breaking the reproductive
cycle of navel orangeworm (NOW). This
highly destructive pest, Amyelois transitella,
overwinters as larvae in nuts left
behind after harvest. Navel orangeworm
larvae feeding damages kernels and can
introduce aflatoxins which threaten
lucrative export markets. Effectively
destroying the windrowed mummy is
the big challenge in pistachio orchard
sanitation.
Sanitation efforts in almond orchards
are carried out much the same way as
pistachios, but are more effective due to
variable ground conditions in pistachio
orchards and the physical differences
of the nuts. The smaller pistachios have
tougher shells make them difficult to
pick up and destroy.
Current Tools
Given the current tools available,
“Sanitation will provide a benefit, but it
won’t have the same impact in pistachio
orchards as it does in almonds,” said
Brad Higbee, research & development
manager at Trécé Inc.
There is no current University of California
(UC) research on numbers of
pistachio mummies left in orchards and
the relationship to NOW populations
the following year. A good pistachio
sanitation guideline is 10-20 mummies
per ten trees. Justin Nay, crop advisor
with Integral Ag of Chico said fewer
than 40 mummies per tree reflects
acceptable sanitation efforts. In almonds
the standard sanitation goal is one
mummy nut in the tree per ten trees
and 5-10 on the ground.
“What we see in pistachios is 100-200,”
Higbee said. “There is a lot of room for
improvement.”
Area–wide sanitation efforts are more
effective in lowering NOW numbers.
If neighbors do no sanitation in their
orchards, NOW infestations grow and
move into nearby orchards, even those
with good sanitation.
NOW Damage
The percentage of NOW damaged or
rejected nuts was high at two percent
last year. With higher numbers of NOW
overwintering, pistachio growers were
expecting to reach that point again
this year. Nay said trapping early in the
growing season showed high numbers
of NOW. Numbers declined in June,
but came back to hit the early split nuts.
Late harvested pistachios are at a higher
risk of NOW infestation.
Most pistachio growers recognize the
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West Coast Nut October 2018