NOW Control Critical
2017 Crop Sees Worst Outbreak Ever
“I’ve never seen this kind of pressure,” Mel Machado,
director of member relations for
Blue Diamond Growers
,
observed in introducing the cultural seminar on “NOW
in 2017” at the annual growers meeting. “At these levels,
a grower cannot afford to neglect prevention.” This
cultural seminar examined changing conditions that have
produced higher numbers of navel orangeworm (NOW)
and recommendations for minimizing crop damage.
Joel Siegel, research entomologist, USDA Agricultural
Research Service, agreed with Machado’s comments
about prevention, adding, “Sanitation alone, however,
will not control NOW, nor will sanitation plus one spray.
What you need to do is a thorough job of sanitation plus
two or more spray interventions to prevent costly worm
damage. Listen to your PCA and do as he recommends.”
Changing Conditions
Siegel described a changing “almond landscape” that
is producing higher numbers of NOW and more flights
than in the past.
• HEAT – Five years of hotter weather has encouraged
NOW reproduction. Today California is experiencing
an extra generation of NOW.
• ACREAGE – The rapid expansion of almond acreage
has produced a monoculture that NOW is following
as plantings spread. With two million acres of nuts
in the state – almonds, walnuts and pistachios –
conditions are ripe for a NOW explosion.
Control
NOW flies around all year but growers need to pay
attention to waves of activity by monitoring pheromone
traps. Siegel noted, however, that mating disruption
programs compromise pheromone traps, so be aware
of what your neighbors are doing.
Remove mummies. Siegel notes that moths lay eggs on
mummies and the adults that emerge come out when
Nonpareil begins to split – early April, beginning of May, at
1,100 degree days. Another flight occurs at 700 additional
degree days, resulting in overlapping flights. Siegel
recommends getting all of the mummy nuts off the trees and
on the ground and shredded so that NOW has nothing to
lay eggs on. Doing so eliminates the first early flight.
NOW also moves into later varieties of almonds from
pistachios, therefore growers need to stay on top of the
waves of flights by careful monitoring, listening to their
PCAs and prompt application of controls.
Spray
Siegel observed that the overlapping flights, waves
of activity and more favorable conditions for NOW
requires more control than ever before, “We need four
to five well-timed sprays to prevent economic damage
to our crops.” Timing is also critical, “Early is better than
late.” He suggests first spray at April 11, at hull split, then
May 5, June 2, June 30, July 28 and September 22 to
deal effectively with NOW.
Siegel pointed out that in addition to timing, coverage is
critical, “Spray that does not enter the suture is a loss.”
Most spray rigs do not reach the top third of the tree
and 99 percent of the spray fails to reach the sutures.
For optimum control and minimum economic loss, Siegel
recommends a rigorous sanitation, monitoring and spray
program that includes maximizing the effectiveness of the
spray rig for full coverage.
The Science of Spraying
Matt Strmiska, engineer with Adaptiv, offered insights on
spray effectiveness. According to Strmiska, the standard
loss at the canopy, some 90 percent, is not from drift, but
from the product not getting to the target – the suture.
Many factors affect coverage, Strmiska said, including
timing, environmental conditions, rate of application,
canopy, machine, laws of physics. “Spraying is, in fact,
ANNUALGROWERSMEETING
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A L M O N D F A C T S
