NOW Tools Create
Year-round
Management and
Have Additional
Benefits
With the proven ability of navel
orangeworm (NOW) populations to spike
from year to year, more tools to monitor
and employ control practices for the pest
are proving viable for growers and create
a year-round management approach.
Recent research has also identified an
additional benefit to the anchor of NOW
integrated pest management, mummy
removal, making the practice worth it
even more.
Learning from the past
Some seasons are permanently
engrained in the heads of growers and
researchers because of unprecedented
negative impacts to the crop.
For almond growers, one of those cases
is navel orangeworm damage in 2017.
"2017 was a nightmare," said Mel
Machado, member relations director
for Blue Diamond Growers. "We had
growers who had never been above
2 percent damage in their lives, who
found themselves living between
8 and 12 percent damage."
Machado has spoken at several
industry events since 2017, including
ABC's Navel Orangeworm Summit in
2019, presenting on the relationship
between NOW damage levels and the
possible financial impact. Assuming a
2,500 pound per acre crop of Nonpareils,
at a market price of $2.50 per pound, 1
percent damage from NOW equates to
a loss of more than $158 per acre. At 2
percent damage, growers could expect
a loss of more than $436 per acre.
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Machado notes that those potential losses
exceed $1,000 per acre at as little as 5
percent damage.
History is known to repeat itself
NOW damage numbers have dropped
since 2017, likely due to the awareness
of financial impacts and the education
around winter sanitation. But what
factors led to the spike in NOW in 2017?
Machado said a big factor is something
familiar to present day.
"Coming out of a drought. We had
poor sanitation and the mummy load had
built up in the fields," he said. "It was a
year where we got some heat during hull
split – much like this year. Hull split slows
down because of the stress on the trees
but the worm continues to progress, so
we extended our susceptibility."
Machado's explanation sounds a lot like
the 2020-21 growing season. Water supply
was stretched thin this year with poor
snowpack accumulation. With lower prices
during much of the season, growers likely
cut input costs where they could.
"Talking to growers this year, we know
they are looking to cut costs where
possible," said Michael Roots, field
outreach and education specialist for
ABC. Roots noted that several reports
from the field about NOW were favorable
but added we will see a slight increase
in the final numbers just because of a
favorable 2019-20 growing season.
"Last season happened to be a really
low-pressure year for navel orangeworm,"
he said. "It looks like damage is probably
going to be up a little bit from last year
due to a bit more pressure, but also with
the current crop being smaller those
percentages may come out a little higher."
ABC's senior pest management
specialist Drew Wolter agreed with the
similarity between this season and the
often-mentioned 2017 year.
"Early flight activity this year is higher
when compared to historical averages,
mimicking 2017's numbers," Wolter said.
"Egg laying was considerably earlier than
prior seasons and trap counts remained
higher than historical averages throughout
the season and valley."
PEST MANAGEMENT
Mating Disruption Tools
for Navel Orangeworm
Monitoring Tools for
Navel Orangeworm
Watch now
1 "How Much Does NOW Damage Cost" https://bit.ly/3m7MvhX
Winter sanitation is essential
for effective integrated pest
management of navel orangeworm.
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