March/April 2023 - 13

PEST MANAGEMENT
third or fourth week of May or
early June, females give live
birth to crawlers. The crawlers
appear as tiny, pale orange
ovals congregated around and
under the adult females in the
nest and quickly move to feed
on the hulls.
In most years, the crawlers'
birth is synchronized and
quick, and crawlers lack the
waxy coating that protects later
instars from insecticides. Late
May/early June is thus the " go
time " point for treatment.
At later dates, the increased
canopy and clusters further
block the spray treatments.
The May/June spray is called
for economically if just one
mealybug is found in every 10
clusters in May. If this May/
June treatment is missed, gobs
of mealybugs may envelop the
clusters later in the season.
Treatment options
For treating mealybugs,
the three best insecticides are
spirotetramat (Movento, IRAC
24), acetamiprid (Assail, IRAC 4A)
and buprofezin (Centaur, IRAC
16). If the May spray is missed,
acetamiprid can be effective
against second generation
crawlers in mid- to late July.
However, Gill's mealybugs in
the Hanford area of the San
Joaquin Valley are showing some
resistance to acetamiprid.
Buprofezin, in turn, should not be used later than March.
The European Union (EU) rejects shipments with
residues higher than the limit of 0.01 ppm for buprofezin.
A good rotation to use all three products would be to
apply spirotetramat in May/June of one year, followed by
buprofezin in March and acetamiprid in May the next year.
Imidacloprid (Admire Pro, IRAC 4A) is less effective
than the previous three insecticides, but its low cost
(less than $10/acre) and ease of application through drip
irrigation make it an acceptable choice with low mealybug
populations. As with buprofezin, tolerances for residues are
extremely low in the EU, so the Administrative Committee
for Pistachios sets guidelines for its use. Growers can check
with their processors on the current guidelines before
applying imidacloprid.
A 2021 insecticide study found that additional products
did well against Gill's mealybug: spirotetramat and
acetamiprid, as before, plus spirotetramat + pyrifoxen
NATIONALNUTGROWER.COM 13
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March/April 2023

Table of Contents for the Digital Edition of March/April 2023

March/April 2023 - 1
March/April 2023 - 2
March/April 2023 - 3
March/April 2023 - 4
March/April 2023 - 5
March/April 2023 - 6
March/April 2023 - 7
March/April 2023 - 8
March/April 2023 - 9
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March/April 2023 - 12
March/April 2023 - 13
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https://www.nxtbook.com/greatamericanmediaservices/NNG/march-april-2024
https://www.nxtbook.com/greatamericanmediaservices/NNG/january-february-2024
https://www.nxtbook.com/greatamericanmediaservices/NNG/november-december-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/september-october-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/july-august-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/may-june-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/march-april-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/january-february-2023
https://www.nxtbook.com/greatamericanmediaservices/NNG/november-december-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/september-october-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/july-august-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/may-june-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/march-april-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/january-february-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/winter-2022
https://www.nxtbook.com/greatamericanmediaservices/NNG/fall-2021
https://www.nxtbook.com/greatamericanmediaservices/NNG/summer-2021
https://www.nxtbook.com/greatamericanmediaservices/NNG/winter-2021
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