UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
DATE:
March
22,
2004
SUBJECT:
Assessment
of
registrant
requests
for
exemptions
to
Re­
Entry
Intervals
(
REI)
for
propargite
use
in
specific
crops
FROM:
Nikhil
Mallampalli,
Entomologist
Angel
Chiri,
Entomologist
Colwell
Cook,
Entomologist
Herbicide
and
Insecticide
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THROUGH:
Arnet
Jones,
Chief
Herbicide
and
Insecticide
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

TO:
Dayton
Eckerson,
Chemical
Review
Manager
Robert
McNally,
Chief
Special
Review
Branch
(
7508C)

Almonds
Propargite
Use
Although
there
are
several
potentially
damaging
mites
on
almonds,
only
three
species
of
spider
mites
may
need
to
be
treated
with
pesticides.
Propargite
is
one
of
several
chemicals
listed
as
being
used
for
mite
control
in
the
2002
Pest
Management
Strategic
Plan
for
Almonds.
The
alternative
miticides
are:
abamectin,
clofentezine,
fenbutatinoxide
hexythiazox
and
narrow­
range
oils.
Propargite
is
applied
post­
bloom
by
ground
to
27
%
of
the
acres,
at
the
rate
of
1.5
lb.
a.
i.
per
acre
(
USDA,
1999).

Issue:
Hand­
weeding
Weed
control
is
accomplished
entirely
through
pre­
and
post­
emergence
herbicide
applications
and
mechanical
mowing.
There
is
no
mention
of
hand­
weeding
in
any
of
the
sources
consulted.
However,
in
the
unlikely
event
that
hand
weeding
is
planned
for
a
small
orchard,
this
activity
could
be
readily
planned
around
a
scheduled
propargite
application.

References
Almond
Board
of
California
and
California
Pest
Management
Center.
2003.
The
Foundation
for
a
Pest
Manage
ment
Strategic
Plan
in
Almond
Producti
on.
Availabl
e
on
the
Web
at:
http://
pe
stdata.
n
csu.
edu/
pmsp/
pd
f/
caalmo
nds.
pdf
Mosz,
N.
2002.
Almond
Timeline.
U.
S.
Environmental
Protection
Agency,
Office
of
Pesticide
Programs,
Biological
and
Economic
Analysis
Division.
Available
on
the
Web
at:
http://
pestdata.
nc
su.
edu/
croptimeli
nes/
pdf/
CAalmon
d.
pdf
USDA.
1999.
Crop
Profile
for
Almonds
in
California.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
caalmonds.
html
Beans,
Dry
Propargite
Use
Spider
mites
are
occasional
pests
of
dry
beans,
and
have
the
potential
to
cause
significant
damage.
For
instance,
although
in
most
years
spider
mites
cause
little
damage
to
beans
in
Idaho
and
Montana,
in
years
of
high
infestations,
spider
mites
can
cause
up
to
80%
yield
loss
in
individual
fields.
In
general,
the
earlier
in
crop
development
that
an
infestation
starts,
the
more
likely
significant
yield
losses
could
occur.
Among
the
10
available
USDA
Crop
Profiles
for
Dry
Beans
(
CO,
ID,
KS,
MI,
MN,
MT,
NE,
NY,
ND,
and
OR)
consulted,
six
of
them
mention
or
discuss
mite
pests,
but
only
one
(
OR)
mentions
propargite
use.
Propargite
is
also
one
of
the
miticides
recommended
for
use
on
dry
beans
in
California
(
Godfrey,
2004).
Alternative
chemicals
recommended
for
spider
mite
control
on
dry
beans
include
dicofol,
esfenvalerate,
and
sulfur
dust.

Issue:
Hand­
weeding/
Thinning
In
general,
weed
control
in
beans
begins
with
a
pre­
plant
tillage
operation,
followed
by
a
pre­
plant
incorporated
or
preemergence
herbicide
application.
The
herbicides
provide
4
to
6
weeks
of
residual
activity.
Weeds
emerging
after
that
time
are
controlled
by
cultivation
and/
or
herbicide
applications
in
between
rows.
Hand
weeding
does
not
appear
to
be
a
common
practice
in
commercial
bean
production.
However,
in
the
event
that
hand
weeding
is
required
in
isolated
instances,
increasing
the
REI
for
propargite
from
7
to
9
days
would
likely
be
an
inconvenience
rather
than
a
major
impediment
to
bean
production.
Beans
are
generally
precision
seeded
with
specialized
planters
to
obtain
the
desired
uniform
plant
spacing
and
prevent
the
need
for
subsequent
thinning.
As
for
hand
weeding,
hand
thinning
does
not
seem
to
be
a
common
practice
in
commercial
bean
production
either.
It
is
unlikely
that
a
two
day
increase
in
the
current
propargite
REI
would
impact
the
timing
of
any
existing
hand
thinning
operation
to
the
extent
that
bean
production
is
affected.

References
Godfrey,
L.
D.
2004.
Dry
Bean
Spider
Mites.
UC
IPM
Pest
Management
Guidelines:
Dry
Beans,
UC
ANR
Publication
3446,
UC
Davis.
Available
on
the
Web
at:
http://
axp.
ipm.
ucdavis.
edu/
PMG/
r52400111.
html
USDA.
1999­
2003.
Crop
Profiles
for
Dry
Beans.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
cropprofiles/
cpsearch.
cfm
Carrots
Grown
for
Seed
Propargite
Use
Although
spider
mites
are
usually
not
a
problem
on
carrots,
falling
in
the
sporadic
or
occasional
pest
category,
at
times
they
may
be
cause
for
concern.
Sulfur
dusts,
insecticidal
soaps,
and
oils
are
other
mite
suppressing
materials
that
may
be
used
on
carrots.
Outbreaks
of
spider
mites
usually
occur
in
localized
areas
in
a
field,
where
spot
treatments
may
be
all
that
is
necessary
(
University
of
California,
2004).
Control
of
insect
pests
and
spider
mites
feeding
on
carrot
foliage,
however
infrequently,
is
essential
to
assure
seed
production
(
Simon,
1999).

Only
3
of
the
13
available
USDA
Crop
Profiles
for
Carrots
(
CA,
FL,
GA,
MI,
MN,
NJ,
NY,
OH,
OR,
TX,
WA,
WI
and
U.
S.)
mention
mites
as
occasional
(
TX)
or
sporadic
(
NY
and
U.
S.)
pests.
None
mentions
propargite
as
an
alternative.
According
to
the
Crop
Profile
for
Carrots
in
New
York,
there
are
no
effective
pesticides
labeled
for
mite
control
in
carrots
in
that
State.
However,
a
cursory
internet
search
revealed
24(
c)
propargite
registrations
for
carrots
grown
for
seed
in
the
states
of
Oregon,
Washington,
and
Idaho.

Issue:
Hand­
weeding/
Thinning
Unlike
carrots
grown
for
the
fresh
market,
which
fully
rely
on
herbicides
for
weed
control
(
Fennimore
et
al.,
2000)
and
may
often
depend
on
precision
seeding
to
reduce
the
need
for
labor­
intensive
thinning,
carrots
grown
for
seed
often
require
hand
weeding
and
hand
thinning
(
Weber
et
al.,
2004).
However,
it
is
highly
unlikely
that
a
2­
3
day
REI
would
interfere
with
any
required
hand
weeding
or
hand
thinning
practice
in
carrots
grown
for
seed,
especially
since
this
represents
a
reduction
from
the
current
7
day
REI.

References
Fennimore,
S.
A.,
S.
J.
Richard,
and
N.
L.
Flewelling.
2000.
Crop
Profile
for
Carrots
in
California.
UC
Davis,
Department
of
Vegetable
Crops.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
cacarrots.
html
Michigan
State
University.
2002.
Pest
Management
in
the
Future:
A
Strategic
Plan
for
the
Michigan
Carrot
Industry.
Available
on
the
Web
at:
http://
pestdata.
nc
su.
edu/
pmsp/
pdf/
micarrots.
pdf
Simon,
P.
W.
1999.
Carrot
Seed
Production,
USDA,
ARS,
Department
of
Horticulture,
University
of
Wisconsin.
Available
on
the
Web
at:
http://
www.
hort.
wisc.
edu/
usdavcru/
simon/
seedprod.
html
University
of
California,
Cooperative
Extension.
2004.
Spider
Mites
on
Carrots.
Available
on
the
Web:
http://
cekern.
ucdavis.
edu/
Custom_
Program573/
Spider_
Mites_
of_
Carrots.
htm
USDA
Crop
Profiles
for
Carrots.
1999­
2003.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
cropprofiles/
cpsearch.
cfm
Weber,
C.,
C.
Campbell,
M.
Butler,
and
B.
Eleveld.
2004.
Enterprise
Budget:
Carrot
Seed
Production
Under
Drip
Irrigation,
Central
Oregon
Region.
Oregon
State
University,
Extension
Service.
Available
on
the
Web
at:
http://
eesc.
orego
nstate.
edu/
agcom
webfile/
EdMat/
e
m8849.
pdf
Cherries
Propargite
Use
Propargite
is
used
to
manage
the
Pacific
spider
mite
and
the
twospotted
spider
mite
in
cherries
after
harvest.
Propargite
is
one
of
several
chemicals
recommended
in
the
UC
Management
Guidelines
for
these
mites.
The
alternative
miticides
are:
clofentezine,
fenbutatin
oxide,
and
oil.

The
USDA
Crop
Profiles
for
cherries
in
New
York,
Virginia,
Oregon,
Washington,
and
Pennsylvania
do
not
mention
propargite.

Issues:
Irrigation,
Scouting,
Hand­
weeding
After
harvest
the
cultural
activities
include:
irrigating,
mowing/
disking,
pruning/
topping,
pesticide
applications,
field
scouting,
fertilizing,
vertebrate
control,
and
tree
removal.
However,
according
to
Rick
Melnicoe
(
personal
communication
March
12,
2004)
few
of
these
activities
are
done
by
hand.
Irrigation
is
primarily
sprinkler
or
flood.
Mowing
is
usually
done
once
to
till.
There
is
not
much
pruning
or
topping
after
harvest,
only
to
take
out
dead
branches.
Scouting
may
occur
once
a
week.
Hand­
weeding
is
not
listed
as
a
post­
harvest
activity
in
the
Pest
Management
Strategic
Plan
for
Cherry
Production
in
California.

References:

Pest
Management
Strategic
Plan
for
Cherry
Production
in
California.
2003.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
pmsp/
index.
cfm.

UC
IPM:
UC
Management
Guidelines
for
Webspinning
Spider
Mites
on
Cherry.
Available
on
the
Web
at:
http://
www.
ipm.
ucdavis.
edu/
PMG/
r105400211.
html
Melnicoe,
Rick.
Director.
Western
Pest
Management
Center,
Davis,
California.
Personal
communication
to
Colwell
Cook,
USEPA/
OPP/
BEAD,
March
12,
2004.

Clover
grown
for
seed
Propargite
Use
Use
targets
two
spotted
and
strawberry
spider
mites.
Chemical
control
is
only
recommended
early
in
the
growing
season,
and
only
for
heavy
infestations
(
Baird
et
al.
1993,
Stein
et
al.
2003).
Alternatives
with
good
efficacy
include
hexythiazox,
kelthane,
and
bifenthrin
(
Baird
et
al.
1993,
Stein
et
al.
2003).
Both
bifenthrin
and
hexythiazox
have
12
hour
REIs.

Issue:
hand
weeding/
thinning
Thinning
is
not
mentioned
as
a
practice
in
the
literature
BEAD
has
been
able
to
locate
on
this
crop.
Weeds
are
a
potentially
devastating
type
of
pest,
since
even
low
levels
of
seed
contamination
can
render
the
harvest
unmarketable
(
Taylor
et
al.
1996).
However,
as
with
the
other
crops,
weed
control
appears
to
be
typically
done
with
herbicides,
of
which
a
variety
are
registered.
While
hand
weeding
is
listed
as
an
option
for
weed
control
in
some
production
guides,
it
is
presented
as
one
of
several
"
mechanical
cultivation"
strategies
(
Taylor
et
al.
1996,
Williams
et
al.
2002).
At
least
one
such
guide
states
that
weeds
can
be
managed
with
mechanical
cultivation
performed
every
10
to
14
days
(
Williams
et
al.
2002).
This
suggests
that
virtually
all
growers
can
continue
to
use
hand
weeding
in
those
(
probably
rare)
instances
where
they
prefer
it
over
the
less
labor
intensive
practices
of
mechanical
disking
or
herbicide
application
­
even
after
propargite
application.
Furthermore,
growers
have
the
option
of
using
bifenthrin
or
hexythiazox
instead
of
propargite
if
they
know
they
need
to
have
a
short
REI
to
control
weeds
concomitantly.
In
light
of
these
management
options,
BEAD
believes
that
while
hand
weeding
does
occur
(
to
an
unknown
extent)
in
clover
seed
production,
an
exception
to
the
propargite
REI
for
this
activity
is
not
necessary.

References
Baird,
C.
R.,
H.
W.
Homan,
and
D.
G.
Bolz.
1993.
Insect
Control
Recommendations
for
Producing
Clover
Seed
in
Idaho.
Pub.
#
CIS
772
of
the
Cooperative
Extension
Service
of
the
University
of
Idaho,
Moscow,
ID.

Stein,
D.,
D.
McGrath,
and
S.
Aldrich­
Markham.
2003.
Clover
Seed
Pests.
Part
of
the
Pacific
North
West
Insect
Management
Handbook.
Available
on
the
Web
at:
http://
insects.
ippc.
orst.
edu/
pnw/
insects?
13LEGU03.
dat.

Taylor,
N.
L.,
D.
M.
TeKrony,
and
J.
Henning.
1996.
Producing
Red
Clover
Seed
in
Kentucky.
Pub.
AGR­
2
of
the
Cooperative
Extension
Service
of
the
University
of
Kentucky,
Lexington,
KY.

Williams,
R.
D.,
D.
Ball,
T.
L.
Miller,
R.
Parker,
J.
P.
Yenish,
T.
W.
Miller,
D.
W.
Morishita,
and
P.
J.
S.
Hutchinson.
2002.
Pacific
North
West
Weed
Management
Handbook.
Available
on
the
Web
at:
http://
weeds.
ippc.
orst.
edu/
pnw/
weeds?
authorscontributors.
html.

Corn
(
Field,
Sweet,
Pop)

Propargite
Use
Propargite
is
one
of
a
few
chemical
control
options
growers
have
to
manage
various
mite
species
that
can
sporadically
become
pests
in
these
crops.
Perhaps
most
important
of
these
pests
are
the
two
spotted
spider
mite,
found
on
a
wide
variety
of
plants,
and
the
Banks
grass
mite,
an
arthropod
specializing
on
grassy
plants.
Mites
are
not
considered
pests
of
corn
grown
east
of
the
Rockies
(
USDA
2003a,
b).
Effective
alternatives
to
propargite
available
on
corn
include
bifenthrin
and
dimethoate.
Both
have
short
REIs
(
24­
48hr),
though
this
may
change
for
dimethoate
as
it
is
undergoing
the
RED
process.

Issue:
hand
weeding
Hand
weeding
is
impractical
in
the
large
commercial
fields
that
produce
most
of
the
corn
in
the
USA,
and
thus
virtually
never
occurs
(
Brassard,
personal
communication).
Weeds
are
managed
with
herbicides,
of
which
a
variety
are
registered
for
use
in
all
corn
types
(
USDA
2003a,
b,
c),
or
disking
and
mowing
at
appropriate
times
in
the
year.
BEAD
does
not
believe
an
exception
is
necessary
for
this
activity.

Issue:
scouting
and
irrigation
Scouting
probably
occurs
once
per
week
in
virtually
all
corn
crops
(
Brassard,
personal
communication);
certified
scouts
are
exempt
from
REI
restrictions
as
per
WPS
guidelines.
Irrigation
is
accomplished
with
either
furrow
or
mechanized
mobile
booms
(
USDA
2003a,
b,
c,
Brassard,
personal
communication).
Thus,
for
irrigation,
only
repair
activities
would
require
quick
field
re­
entry,
and
this
is
exempt
to
the
extent
that
WPS
guidelines
allow.
Note
that
for
all
activities
that
an
exception
has
been
requested,
effective
alternatives
to
propargite
exist
for
corn,
and
these
alternatives
currently
retain
short
REIs
(
see
above).

References
Brassard,
D.
Senior
Entomologist,
USEPA/
OPP/
BEAD.
Personal
communication
to
Nikhil
Mallampalli,
USEPA/
OPP/
BEAD.

USDA.
2003a.
Crop
Profile
for
Sweet
Corn
in
the
North
Central
United
States.
Available
on
the
Web
at:
http://
cipm.
ncsu.
edu/
cropprofiles/.

USDA.
2003b.
Crop
Profile
for
Field
Corn
in
Colorado.
Available
on
the
Web
at:
http://
cipm.
ncsu.
edu/
cropprofiles/.

USDA.
2003c.
Crop
Profile
for
Corn
(
Pop)
in
the
United
States
(
North
Central
Region).
Available
on
the
Web
at:
http://
cipm.
ncsu.
edu/
cropprofiles/.

Grapefruit
Propargite
Use
In
California,
only
about
1
%
of
the
citrus
acreage
has
been
treated
with
propargite
in
recent
years
(
USDA
2001a).
The
vast
majority
of
this
acreage
is
planted
to
non­
grapefruit
citrus
(
USDA
2001a).
The
targeted
pest
is
the
citrus
red
mite.
Alternatives
also
in
use
against
this
pest
include
dicofol,
oxythioquinox,
narrow­
range
oil,
avermectin,
and
pyridaben.
Of
these,
pyridaben
and
oil
are
the
most
commonly
used
and
are
at
least
as
efficacious
as
propargite
(
USDA
2001a,
Grafton­
Cardwell,
personal
communication).

In
Florida,
propargite
use
targets
citrus
rust
mites
and
spider
mites,
of
which
the
rust
mite
is
considered
the
more
consistently
serious
pest
(
USDA
2001b).
Pyridaben,
ethion,
fenbutatin
oxide,
avermectin,
narrow­
range
oil,
and
sulfur
have
all
been
used
as
effective
alternatives
against
these
pests
(
USDA
2001b,
Childers
et
al.
2004).

Issue:
Scouting
The
University
of
Florida
extension
service
recommends
that
mites
be
monitored
every
10­
14
days
(
if
fruit
are
intended
for
the
fresh
market)
or
every
2­
3
weeks
if
processed
fruit
are
being
produced
(
Childers
et
al.
2004).
Detailed
sampling
methods
have
been
developed
(
Childers
et
al.
2004),
and
do
not
appear
to
require
more
than
a
day
at
a
time
to
perform.
Thus,
BEAD
believes
that
scouting
can
be
carried
out
with
the
proposed
REI
(
36
days).
Indeed,
growers
have
been
operating
with
a
28
day
REI
already.
Further,
as
with
all
other
crops,
WPS
guidelines
also
allow
for
certified
scouts
to
be
exempt
from
REI
restrictions.

Issue:
Hand
weeding
This
practice
appears
to
be
virtually
nonexistent
in
conventional
commercial
U.
S.
citrus
production
systems.
Weeding
is
typically
carried
out
using
pre­
emergent
herbicides,
disking,
and
mowing
row
middles,
and
growing
leguminous
cover
crops,
depending
largely
on
the
growing
region
(
USDA
2001a,
2001b).
BEAD
does
not
believe
an
exemption
for
hand
weeding
is
necessary.

Issue:
Irrigation
This
is
achieved
using
either
fixed
microsprinkler
systems,
drip
lines,
or
flood/
furrow
irrigation
systems
(
USDA
2001a,
2001b).
Quick
re­
entry
into
propargite
treated
fields
should
only
be
necessary
for
emergency
repairs,
which
is
allowed
under
current
WPS
guidelines.
Therefore,
BEAD
does
not
believe
there
is
a
critical
need
for
a
1
day
exception
to
the
proposed
REI.

References
Childers,
C.
C.,
C.
W.
McCoy,
H.
N.
Nigg,
and
P.
A.
Stansley.
2004.
Florida
Citrus
Pest
Management
Guide:
Rust
Mites,
Spider
Mites,
and
Other
Phytophagous
Mites.
Pub.
#
ENY­
603
of
the
University
of
Florida
Extension
Service.
Available
on
the
Web
at
http://
edis.
ifas.
ufl.
edu.

Grafton­
Cardwell,
E.
IPM
entomologist,
University
of
California
at
Riverside.
Personal
communication
to
Nikhil
Mallampalli,
USEPA/
OPP/
BEAD.

USDA.
2001a.
Crop
Profile
for
Citrus
in
California.
Available
on
the
Web
at
http://
cipm.
ncsu.
edu/
cropprofiles/

USDA.
2001b.
Crop
Profile
for
Citrus
(
Major)/
Grapefruit
in
Florida.
Available
on
the
Web
at
http://
cipm.
ncsu.
edu/
cropprofiles/

Hops
Propargite
Use
Use
targets
mainly
two
spotted
spider
mites,
as
well
as
other
mites
species
that
are
less
consistently
pests
of
this
crop
(
USDA
1999,
2001).
While
mites
can
be
devastating
pests
of
this
crop,
a
range
of
alternative
chemical
control
options
exist.
Those
with
efficacy
comparable
to
or
better
than
that
of
propargite
are:
hexythiazox,
avermectin,
dicofol,
and
bifenazate.
Fenpyroximate
was
also
available
in
the
major
hops
producing
states,
Idaho
and
Washington,
under
a
Section
18
exemption,
until
2003.
It
is
not
clear
whether
this
exemption
has
been
renewed
for
2004.
Of
these,
hexythiazox
is
an
ovicide
that
is
very
effective
if
timed
properly
(
USDA
2001),
and
bifenazate
and
fenpyroximate
are
mite­
specific
chemicals
that
also
have
good
efficacy
and
relatively
short
REIs
(
12
hours),
thus
providing
an
option
for
those
rare
growers
who
cannot
adapt
to
the
new
REIs
for
propargite.

Issue:
hand
weeding
This
activity
is
probably
never
practiced
in
commercial
hops
production.
While
weeds
can
be
a
significant
pest
problem,
mechanical
cultivation
of
row
middles
is
the
typical
control
strategy
(
USDA
2001b).
Mulch
is
also
applied
to
suppress
weed
germination.
Therefore,
BEAD
believes
that
an
exemption
for
hand
weeding
is
unnecessary
for
this
crop.
Various
herbicides
are
also
available
for
efficacious
chemical
control
of
weeds
(
USDA
1999,
2001).

References
USDA.
1999.
Crop
Profile
for
Hops
in
Oregon.
Available
on
the
Web
at:
http://
cipm.
ncsu.
edu/
cropprofiles/.

USDA.
2001.
Crop
Profile
for
Hops
in
Washington.
Available
on
the
Web
at:
http://
cipm.
ncsu.
edu/
cropprofiles/.

Walnuts
Propargite
Use
Propargite
is
one
of
several
miticides
that
are
applied
post­
bloom
to
walnuts,
primarily
to
control
the
two­
spotted
and
Pacific
mites
(
USDA,
1998).
These
two
spider
mites
can
cause
almost
complete
defoliation,
exposing
trees
and
nuts
to
sunburn
and
reducing
nut
size.
In
well­
managed
orchards,
arthropod
predators
keep
populations
levels
of
other
mite
species
below
damaging
levels
most
of
the
time.
Mite
populations
that
exceed
recommended
economic
threshold
levels
are
controlled
with
a
single
post­
bloom
chemical
application.
Mites
can
become
a
problem
from
June
through
August
(
University
of
California,
2004).
Available
miticides
include
narrow­
range
oil,
propargite,
fenbutatin­
oxide,
abamectin,
dicofol,
or
chofentezine
(
USDA,
1998,
University
of
California,
2004).

Issue:
Pruning
Pruning
takes
place
in
the
dormant
season
(
Mosz,
2002)
and
should
not
interfere
with
the
post­
bloom
propargite
applications
needed
to
control
spider
mites
during
June
through
August.

Issue:
Tree
Shaking
Walnut
harvesting
operations
occur
daily
from
early
August
through
mid
October
and
are
largely
automated.
First,
the
orchard
floor
is
rolled
or
dragged
clean
of
twigs,
rocks
and
other
orchard
debris.
Next,
trees
are
shaken
to
dislodge
the
walnuts.
This
operation
is
accomplished
by
means
of
self­
propelled
mechanical
shakers
outfitted
with
a
long
boom
that
clasps
and
shakes
the
tree
or
large
branches,
causing
the
walnuts
to
drop
to
the
ground.
The
shaker
operator
is
protected
inside
a
cab
which,
in
newer
models,
is
closed,
air­
conditioned,
and
air­
filtered.
The
dislodged
nuts
are
then
swept
into
rows
by
a
mechanical
sweeper
to
allow
mechanical
harvesters
to
pick
them
up
for
cleaning
and
hulling.
The
mechanical
sweepers
and
harvesters
lack
enclosed
cabs.
Workers
may
enter
the
orchard
at
this
time
to
remove
sticks
from
the
nut
piles
to
make
pick
up
easier
(
Mosz,
2002,
California
Walnuts,
undated).

Since
propargite
may
be
applied
to
walnuts
during
June
through
August,
and
harvesting
operations
begin
in
early
August,
a
30
REI
would
mean
that
the
last
propargite
application
would
have
to
be
made
in
early
July
to
allow
for
harvest­
related
worker
activities.

Issue:
Hand­
weeding
Weeds
are
typically
controlled
with
applications
of
pre­
emergence
and
post­
emergence
herbicides,
or
a
combination
of
the
two
(
USDA,
1998).
However,
hand­
hoeing
of
weeds
may
also
occur
in
young
orchards
as
needed
(
Mosz,
2002).
In
such
cases,
a
30
day
REI
for
propargite
has
the
potential
to
interfere
with
this
practice.

References
California
Walnuts.
undated.
Available
on
the
Web
at:
http://
www.
walnuts.
org/
walnuts/
wnt_
growing.
shtml
Mosz,
N.
2002.
Walnut
Timeline.
U.
S.
Environmental
Protection
Agency,
Office
of
Pesticide
Programs,
Biological
and
Economic
Analysis
Division.
Available
on
the
Web
at:
http://
pestdata.
nc
su.
edu/
cropTimel
ines/
pdf/
CAwaln
ut.
pdf
University
of
California.
2004.
UC
IPM
Pest
Management
Guidelines:
Integrated
Pest
Management
for
Walnuts.
Available
on
the
Web
at:
http://
www.
ipm.
ucdavis.
edu/
PMG/
r881400111.
html#
WHEN
USDA.
1998.
Crop
Profile
for
Walnuts
in
California.
Available
on
the
Web
at:
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
cawalnuts.
html
