UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
Analysis
of
Disulfoton
Use
on
Fraser
Fir
Christmas
Trees
in
Western
North
Carolina.

FROM:
Colwell
A.
Cook,
Entomologist
Michael
K.
Hennessey,
Entomologist
Herbicide
and
Insecticide
Branch
Biological
and
Economic
Analysis
Division
THRU:
Arnet
Jones,
Chief
Herbicide
and
Insecticide
Branch
Biological
and
Economic
Analysis
Division
TO:
Christina
Scheltema,
Chemical
Review
Manager
Betty
Shackelford,
Branch
Chief
Reregistration
Branch
3
Special
Review
and
Reregistration
Division
DATE
OF
PEER
REVIEW:
July
3,
2002
Introduction
The
Special
Review
and
Reregistration
Division
(SRRD)
has
requested
that
the
following
documents,
originally
prepared
by
Michael
K.
Hennessey
and
incorporated
below,
be
reviewed
prior
to
their
being
placed
in
the
docket
and
on
the
web.
These
documents
were
originally
written
to
answer
if
the
organophosphate,
disulfoton,
was
critical
to
the
Fraser
fir
Christmas
tree
industry
in
western
North
Carolina.

BEAD
has
reviewed
the
documents
and
has
determined
that
they
reflect
the
state
of
knowledge
for
the
time
in
which
they
were
written,
July
2000.
BEAD
feels
compelled
to
mention
that
several
of
the
alternatives
listed
in
the
documents
are
currently
under
review
for
reregistration
and
some
chemicals
are
still
in
the
registration
pipeline
and
should
not
be
considered
as
alternatives.

The
following
are
Mike's
documents
submitted
to
SRRD
on
July
5,
2000.
2
Site:
Fraser
Fir
Christmas
Trees
This
analysis
focuses
on
the
level
of
need
for
OPs
and
alternatives
for
Fraser
firs.

All
Fraser
firs
are
grown
in
the
mountainous
areas
of
North
Carolina
where
they
are
the
major
agricultural
commodity.
They
are
perennial
with
a
6­
10
year
crop
cycle.
In
1996,
34
million
trees
were
grown
on
24,000
acres
by
1,600
growers.
Over
66%
of
the
growers
had
<10
acres.
About
10­
20%
of
the
trees
are
harvested
annually
around
Christmastime.
Seventy­
five
percent
of
the
harvest
is
for
the
wholesale
market
and
25%
is
for
the
retail,
choose­
and­
cut
market.
The
value
for
1996
was
$78
million
and
for
1999
was
$122
million.
Trees
for
harvest
are
graded
either
by
USDA
or
according
to
the
NC
Christmas
Tree
Association
standards.
Fraser
firs
represented
27%
of
the
US­
grown
Christmas
tree
market
in
1999.
Commercial
Christmas
trees
of
other
varieties
are
mainly
grown
in
OR,
MI,
WA,
OH,
and
WI.
Six
pests
are
of
concern
to
growers.
OPs
are
critically
needed
for
four
of
the
pests.
Crop
loss
comes
mainly
from
cosmetic
damage
to
foliage
visible
in
the
last
year
or
two
before
harvest
or
tree
death
(balsam
wooly
adelgid).
Before
the
last
two
years,
trees
can
usually
compensate
for
foliage
loss.
Large
trees
(6­
7
ft
tall)
are
most
valuable.
Choice
of
pesticide
for
a
given
pest
depends
upon
timing,
row
spacing,
land
slope,
size
of
trees,
and
acreage.
Generally,
pesticides
applied
foliarly
on
small
trees
may
not
be
suitable
for
large
trees
after
canopies
are
closed.
Small
acreage
(because
of
cost)
and
acreage
planted
without
tractor
rows
are
not
generally
amenable
to
foliar
spraying
that
requires
access
by
truck
or
tractor.
Because
of
mountainous
terrain,
aerial
spraying
is
not
generally
done.

Balsam
twig
aphid
and
spruce
spider
mite
are
widespread
and
perennial
pests.
Impacts
are
greatest
near
harvest
when
trees
may
be
downgraded
for
cosmetic
damage.
Disulfoton,
a
systemic
soil
granular
applied
by
either
hand
or
motorcycle,
is
most
used
followed
by
foliarlyapplied
chlorpyrifos
and
esfenvalerate.
Disulfoton
has
the
advantages
of
controlling
both
balsam
twig
aphid
and
spuce
spider
mite,
and,
being
systemic,
conserving
predators.
Disulfoton
and
esfenvalerate
may
be
alternated
if
resistance
management
becomes
an
issue.
Chlorpyrifos
and
esfenvalerate
must
be
foliarly­
applied
by
commercial
applicator
by
mist
blower
or
high­
powered
hose
sprayer.
The
chlorpyrifos
foliar
spray
is
phytotoxic
in
some
situations.
Foliar
applications
are
problematic
because
they
are
usually
uneven,
which
significantly
affects
efficacy.
Disulfoton
is
also
the
pesticide
most
used
against
spruce
spider
mite,
followed
by
chlorpyrifos.
Esfenvalerate
has
the
advantage
of
also
controlling
balsam
wooly
adelgid
to
a
limited
extent
but
the
disadvantage
of
causing
spider
mite
populations
to
increase.

The
other
four
pests
are
minor
but
may
be
important
in
spotty
situations.
Hemlock
rust
mite
and
rosette
bud
mite
are
mainly
controlled
with
foliarly­
applied
dimethoate.
There
is
no
alternative
to
dimethoate
for
rosette
bud
mite.
Balsam
wooly
adelgid
is
a
major
pest
of
spotty
distribution
that
is
mainly
controlled
with
esfenvalerate
spraying.
If
it
is
not
controlled,
the
tree
is
killed
or
culled.
White
grubs
are
not
very
widespread
and
are
controlled
with
soil­
applied
chlorpyrifos
at
plant.

Overall,
for
trees
nearing
harvest,
twig
aphids
and
spider
mites
are
the
critical
pests
3
annually.
Under
those
conditions,
disulfoton
is
the
OP
that
is
critically
needed
because
alternatives
are
somewhat
ineffective.
Without
disulfoton,
a
significant
amount
of
loss
from
downgrading
and
extra
application
costs
would
be
sustained
over
the
region
annually.
Disulfoton
is
important
in
resistance
management
and
conserving
beneficials.

Sources:
USDA
Crop
Profile
for
Christmas
Trees
in
the
North
Carolina
Mountains.
11/
99.
Personal
Observation.
NC
Christmas
Tree
Crop
tour
with
NC
Cooperative
Extension
Service.
6/
25­
27/
00.
Pesticide
labels.
Metasystox­
R,
Dimethoate
4EC,
Di­
Syston
15%,
Lorsban
4E.
6/
00.
Sidebottom,
J.
Personal
communication.
6/
22/
00.
Sidebottom,
J.
1999.
NC
Crop
Profile
Christmas
Trees,
Mountain.
1997
North
Carolina
Christmas
Tree
Survey.
NCASS.
3/
98.
Www.
agr.
state.
nc.
us/
stats/
trees/
xmastree.
htm
Prepared
by:
Michael
K.
Hennessey,
Entomologist,
EPA/
OPP/
BEAD/
HIB,
7/
5/
00.
OP
TOLERANCE
REASSESSMENT
USE/
USAGE
MATRIX
CROP
SUMMARY
4
Site:
Fraser
Fir
Christmas
Trees
Overall
Confidence
Rating:
H
Background:
this
analysis
focuses
on
OP
use.
North
Carolina
is
the
only
producer.
Perennial
crop
with
6­
10
year
crop
cycle.
34
million
trees
were
grown
on
24,000
acres
with
1,600
growers
in
1996.
66%
of
the
farms
are
<10
acres.
93%
of
the
trees
were
grown
in
five
NC
counties.
Trees
are
cut
and
shipped
fresh
for
homeowner
ornamental
use
around
Christmastime
annually.
25%
of
the
trees
sold
are
retail.
Value
was
$78
million
in
1996
and
$122
million
in
1999.
Commodity
represented
27%
of
all
US
grown
Christmas
trees
sold
in
1999.
Commercial
Christmas
trees
of
other
varieties
are
produced
in
OR,
MI,
WA,
OH,
and
WI.

%
Treated
#
Applications
Rate
(lb
AI/
A)
PHI
(days)

Organophosphate
Pesticides
Max
Avg
Max
Avg
Max
Avg
Min
Avg
Disulfoton
72
65
2
1
4.5
3
2
>14
Chlorpyrifos
7
62
11
0.
2511
Oxydemeton
methyl
2
1
2
1
1
0.
5
3
3
Dimethoate
11
10
2
1
0.67
0.67
2
2
Confidence
Rating:
H=
high
confidence
=
data
from
several
confirming
sources;
confirmed
by
personal
experience
M
=
medium
confidence
=
data
from
only
a
few
sources;
may
be
some
conflicting
or
unconfirmed
info.
L
=
low
confidence
=
data
from
only
one
unconfirmed
source
Organophosphate
Target
Pests
for
Fraser
Fir
Major
balsam
twig
aphid,
spruce
spider
mite
Minor
hemlock
rust
mite,
rosette
bud
mite,
balsam
wooly
adelgid,
white
grubs
Major
=
20+%
of
all
OP
usage
on
pest;
Moderate
=
5­
20%
of
all
OP
usage
on
pest;
Minor
=<
5%
of
all
OP
usage
on
pest
Sources:
USDA
Crop
Profile
for
Christmas
Trees
in
the
North
Carolina
Mountains.
11/
99.
Personal
Observation.
NC
Christmas
Tree
Crop
tour
with
NC
Cooperative
Extension
Service.
6/
25­
27/
00.
Pesticide
labels.
Metasystox­
R,
Dimethoate
4EC,
Di­
Syston
15%,
Lorsban
4E.
6/
00.
Sidebottom,
J.
Personal
communication.
6/
22/
00.
Sidebottom,
J.
1999.
NC
Crop
Profile
Christmas
Trees,
Mountain.
1997
North
Carolina
Christmas
Tree
Survey.
NCASS.
3/
98.
Www.
agr.
state.
nc.
us/
stats/
trees/
xmastree.
htm
Prepared
By:
Michael
K.
Hennessey
Date:
7/
5/
00
Time:
17:
00
OP
TOLERANCE
REASSESSMENT
USE/
USAGE
MATRIX
­
PEST
SUMMARY
Page
5
5
Pest
Organophosphate
Efficacy
Mkt
Class
Alt.
Pesticide
List
Efficacy
Mkt
Constraints
of
Alternatives
Crop:
Fraser
fir
Christmas
Trees
Region:
North
Carolina
Timing:
All
plant
stages
balsam
twig
aphid
(Major)
disulfoton
(
hi
P
esfenvalerate
 

 
med
Esfenvalerate
has
an
advantage
of
also
controlling
adelgid
but
disadvantage
of
flaring
spider
mite.

Liquids
(esfenvalarate
and
oxydemeton
methyl,
2
apps
required)
are
difficult
to
apply

–coverage/
efficacy
is
poor
with
hose
or
mist
blower
most
of
the
time
depending
on
spacing
or
size
of
trees.
Chlorpyrifos
causes
some
phytotoxicity.

Predators
are
important
and
are
killed
off
by
foliar
sprays
of
esfenvalerate
and
chlorpyrifos.
Tau

fluvalinate
(good
efficacy),
imidacloprid,
azadirachtin
(good
efficacy)
and
bifenthrin
are
registered
but
not
used.
Triazimate
and
pymetrozine
are
in
EPA
pipeline.

chlorpyrifos
 

 
med
O
imidacloprid
 

 
lo
dimethoate
 
lo
O
cinnamaldehyde
 

 
lo
oxydemeton
methyl
 
lo
spruce
spider
mite
(Major)
disulfoton
(
hi
O
abamectin
 
lo
Oil,
tau­
fluvalinate
(good
efficacy
adults
only),

pyridaben
(good
efficacy),
and
bifenthrin
(not
effective
on
eggs)
are
registered
for
this
but
not
used.

Hexythiazox
doesn't
control
adults.
Bifenazate
(good
efficacy)
and
clofentazine
are
in
research
pipeline.

Chlorpyrifos
causes
some
phytotoxicity.

oxydemeton
methyl
 
lo
O
hexythiazox
 

 
lo
chlorpyrifos
 
med
hemlock
rust
mite
(Minor)
dimethoate
(
hi
O
sulfur
 
lo
Pyridaben
(good
efficacy)
is
registered
but
not
used.

Sulfur
was
experimental
use
only.
Clofentazine
in
research
pipeline.

rosette
bud
mite
(Minor)
dimethoate
(
med
Clofentazine
in
research
pipeline.

balsam
wooly
adelgid
(Minor)
oxydemeton
methyl
 
lo
imidacloprid
 
lo
Esfenvalerate
took
over
for
lindane
that
was
cancelled.
It
must
be
applied
by
high­
pressure
hose.

Older
trees
with
infestations
are
culled.

Predators
are
important
and
they
are
killed
off
by
sprays.
Pymetrozine
is
in
research
pipeline.

Some
phytotoxicity
with
chlorpyrifos,
oil,
and
soap.

chlorpyrifos
 
lo
esfenvalerate
(
hi
oil
 
lo
soap
 
lo
OP
TOLERANCE
REASSESSMENT
USE/
USAGE
MATRIX
­
PEST
SUMMARY
Page
6
Pest
Organophosphate
Efficacy
Mkt
Class
Alt.
Pesticide
List
Efficacy
Mkt
Constraints
of
Alternatives
Crop:
Fraser
fir
Christmas
Trees
Region:
North
Carolina
Timing:
All
plant
stages
6
white
grubs
(Minor)
chlorpyrifos
 
lo
O
methyl
bromide
(
med
Soil
application.
Preplant
soil
methyl
bromide
is
for
root
rot
but
would
kill
grubs
also.
Halofenozide
soil
use
in
EPA
pipeline.

ADDITIONAL
INFORMATION:
For
above,
(
­excellent,
 
­good,
 
­poor.
Market
share:
hi=>
20%,
med=
5­
20%,
lo=<
5%.

Class:
P=
pyrethroid,
O=
other
SOURCES:
USDA
Crop
Profile
for
Christmas
trees
in
North
Carolina
mountains
(Fraser
fir)

Sidebottom,
J.
1/
00.
Registered
alternatives
for
Fraser
fir.

Sidebottom,
J.
6/
00.
Alternatives
to
Di­
syston
15G.

Personal
observation
and
talks
with
growers
and
extension
personnel
D.
Hundley,
J.
Sidebottom,
J.
Moody,
J.
Owen.
Extension
tour
of
Fraser
fir
in
NC.
6/
25­
27/
00.

Prepared
By:
M.
Hennessey,
Entomologist,
OPP/
BEAD,
703­
308­
7076.

Date:
7/
5/
00
Time:
17:
00
