UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
March
23,
2005
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
Pecans
Benefits
Assessment
for
Dicofol
FROM:
Don
Atwood,
Entomologist
Biological
Analysis
Branch
Steve
Smearman,
Economist
Jin
Kim,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THRU:
Arnet
Jones,
Branch
Chief
Biological
Analysis
Branch
David
Widawsky,
Branch
Chief
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

Peer
Review
Panel
Date:
November
17,
2004
TO:
Mika
Hunter,
Chemical
Review
Manager
Reregistration
Branch
2
Special
Review
and
Reregistration
Division
(
7508C)

SUMMARY
Based
on
available
data,
BEAD
believes
that
extending
the
restricted
entry
intervals
(
REI)
for
dicofol
will
result
in
no
impact
on
pecan
production.
Dicofol
is
applied
to
control
mites
from
July
through
the
end
of
October.
The
only
field
activities
during
this
period
are
irrigation,
mowing,
and
windrow
cleaning
prior
to
harvest.
These
are
all
exempt
or
low
contact
activities.
BEAD
believes
that
producers
have
the
ability
to
schedule
these
activities
around
dicofol
application
and
that
extending
the
REI's
should
have
no
impact.
2
BACKGROUND
Pecan,
Carya
illinoensis,
is
native
to
the
southern
regions
of
the
US
where
production
includes
harvest
of
both
native
and
improved
varieties.
Native
pecans
are
established
through
the
natural
spread
of
seed.
Improved
pecan
varieties
(
whether
through
selection,
breeding,
or
grafting)
are
grown
in
orchard
configuration.
Nearly
all
commercial
pecans
are
improved
varieties
which
produce
a
more
desirable
nut
and
also
exhibit
a
greater
yield
to
production
input
ratio.

Crop
Phenology
Pecan
trees
may
reach
a
height
of
100
feet
and
can
live
for
over
80
years,
some
native
pecans
are
200­
300
years
old.
Pecan
orchards
vary
in
size
from
1
acre
to
over
2000
acres
with
typical
size
of
10­
50
acres.
Improved
pecan
groves
are
typically
planted
at
27
trees
per
acre
and
thinned
to
8
trees
per
acre
over
the
next
18­
20
years.
Tree
thinning
allows
for
optimal
light
penetration
and
allows
for
better
pesticide
application.

Pecan
trees
are
dormant
during
winter
months,
typically
from
January
through
March.
Bud
break
occurs
in
early
spring
followed
by
bloom
and
pollination,
usually
in
May.
Although
pecan
trees
have
both
male
and
female
flowers,
the
flowers
mature
at
different
times
and
therefore
require
cross­
pollination.
Pecans
drop
flowers
and
nuts
three
times
during
the
year:
in
May,
late
June,
and
August.
Nut
elongation,
expansion,
and
kernel
development
occurs
in
the
summer
and
extends
into
the
fall,
approximately
6
weeks.
The
shuck,
outer
fleshy
covering
of
the
shell
of
the
nut,
splits
after
kernel
maturity.
Harvest
occurs
in
mid
to
late
fall.

Mechanical
harvesting
is
the
predominant
harvesting
technique
in
the
US.
Tractor­
mounted
hydraulic
shakers
dislodge
nuts
from
the
trees,
and
soon
thereafter
the
fallen
nuts
are
commonly
wind­
rowed
and
swept
up
from
the
ground.
Catch
frames
are
used
in
some
orchards
to
catch
the
nuts
before
they
reach
the
ground.
Mowing
is
necessary
close
to
harvest
to
provide
a
weed­
free
orchard
floor
for
sweeping.

Production
Data
for
Pecans
The
production
of
pecan
mainly
are
from
Georgia
(
27%),
Texas
(
25%),
New
Mexico
(
20%),
Arizona
(
7%),
Oklahoma
(
6%),
Alabama
(
5%),
and
Louisiana
(
3%).
Two
types
of
pecan
have
been
produced
in
the
United
States:
native/
seedling
varieties
and
improved
varieties.
The
improved
varieties
of
pecan
trees
accounts
for
over
75
percent
of
national
production
of
pecan
in
the
United
States
(
USDA/
ERS,
2003).

Use
and
Usage
for
Pecan
Over
the
past
3
years,
dicofol
has
been
used
for
pecan
production
in
Georgia
and
Louisiana.
Nationally,
the
percentage
treated
acres
with
dicofol
was
4.3%
in
2001,
9.2%
in
2002,
and
9.7%
in
2003.
The
most
widely
used
insecticides
for
pecan
are
chlorpyrifos
(
32.5%),
imidacloprid
3
(
12.1%),
tebufenozide
(
9.9%),
cypermethrin
(
9.8%),
and
dicofol
(
9.7%).
Georgia
accounts
for
more
than
90%
of
the
total
acres
treated
with
dicofol
in
the
United
States.
In
Georgia,
the
percentage
treaded
acres
are
63.2%
with
chlorpyrifos,
34.1%
with
dicofol,
33.6%
with
imidacloprid,
and
29.5%
with
cypermethrin.
Table
1
illustrates
the
dicofol
use
and
usage
for
pecan
in
Georgia
and
Louisiana.

Table
1:
Dicofol
Use
and
Usage
for
Pecan
State
Year
Application
rate
Total
Acres
Grown
in
U.
S.
Total
Acres
Grown
in
each
state
(%
of
the
total
acres
in
U.
S.)
Approximated
Base
Acres
Treated
(
BAT)
in
each
state
%
Crop
Treated
Acres
in
each
state
Georgia
2001
1.52
lb
per
acre
496,997
131,873
(
26.6%)
21,273
16.1%

2002
1.36
lb
per
acre
496,997
131,873
(
26.6%)
45,633
34.6%

2003
1.48
lb
per
acre
496,997
131,873
(
26.6%)
44,954
34.1%

Louisiana
2001
0.75
lb
per
acre
496,997
15,091
(
3.0%)
1,902
12.6%

2002
0
496,997
15,091
(
3.0%)
0
0%

2003
1.0
lb
per
acre
496,997
15,091
(
3.0%)
3,176
21%

Source:
EPA
data
2001,
2002,
and
2003.

TARGET
PEST
FOR
DICOFOL
IN
PECANS
The
primary
pest
which
is
controlled
by
dicofol
in
pecan
production
is
the
pecan
leaf
scorch
mite,
Eotetranychus
hicoriae.
Scorch
mites
overwinter
as
adults
in
the
rough
bark
of
limbs.
Adult
females
begin
laying
eggs
in
the
spring.
Mites
can
complete
a
generation
in
5
to
15
days
and
are
more
numerous
during
hot,
dry
weather.
These
pests
are
generally
most
numerous
during
late
season,
between
July
1
and
the
end
of
October.

Large
numbers
of
these
tiny
scorch
mites
feed
under
thin
silken
webs
on
the
undersides
of
pecan
leaves.
Mites
suck
plant
sap
and
cause
irregular
brown
spots
on
infested
leaves.
Leaf
infestation
usually
develops
first
along
the
leaf
midrib.
Large
infestations
can
result
in
leaf
loss,
particularly
when
trees
are
under
moisture
stress.
Scorch
mites
prefer
the
shady,
interior
portion
of
the
tree
and
significant
damage
can
occur
before
infestations
are
detected.
Early
infestation
usually
occurs
on
the
lower
branches.
Mites
may
increase
following
the
use
of
some
insecticides
(
carbaryl)
applied
for
hickory
shuckworm,
aphids
or
other
pests.
It
is
important
to
monitor
pecan
orchards
for
mites
during
hot
dry
weather
and
after
an
insecticide
application.
In
many
cases,
4
spot
treatments
of
infested
trees
will
provide
control
of
scorch
mites.
Natural
enemies
of
scorch
mites,
including
predatory
mite
species,
are
important
in
controlling
these
pests.

BIOLOGICAL
IMPACT
OF
INCREASED
RESTRICTED
ENTRY
INTERVALS
The
current
REI
for
dicofol
application
in
pecans
is
12
hours.
New
labeling
increases
the
REI
to
13­
26
days
for
low
contact
activities
and
43­
56
days
for
high
contact
activities
at
application
rates
of
1.5
and
3
lbs/
acre,
respectively.
Appendix
A
provides
information
on
scorch
mite
occurrence
and
field
activities
which
are
concurrent
with
control
measures.
The
field
activities
that
would
be
of
concern
are:
irrigation,
mowing,
and
windrow
debris
clearing
in
preparation
for
mechanical
harvest.
All
of
these
activities
can
be
considered
low
contact
or
no
contact
activities
due
to
the
size
of
the
trees
and
crop
phenology.
In
addition,
due
to
mechanical
harvesting
of
the
nuts,
there
should
be
no
contact
with
the
treated
nuts.
Several
alternative
insecticides
are
available
to
control
mite
pests
on
pecans
including
bifenezate
and
propargite,
both
of
which
have
a
12
hr
REI.

ECONOMICAL
IMPACT
OF
INCREASED
RESTRICTED
ENTRY
INTERVALS
No
economic
impacts
will
occur
from
extension
of
the
REI
for
dicofol
use
on
pecans.
Dicofol
will
still
be
available
for
use
with
no
resulting
increase
in
application
cost
which
would
be
associated
with
a
change
to
a
different
miticide.
Due
to
the
mechanical
nature
of
pecan
harvest,
with
no
human
exposure
to
treated
nuts,
no
economic
impact
would
be
expected
from
extending
the
REI
to
those
proposed
for
low
contact
activities.

CONCLUSIONS
There
will
be
no
biological
or
economic
impact
from
extension
of
the
REI's
for
dicofol
use
on
pecans.
Dicofol
can
still
be
effectively
used
during
the
normal
period
of
mite
outbreaks
with
no
adverse
impact
on
field
activities.

LITERATURE
CITED
USDA
Crop
Profiles
for
Pecans
in
Texas,
May,
2002
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
txpecans.
html
USDA
Crop
Profiles
for
Pecans
in
North
Carolina,
December
1999.
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
ncpecans.
html
USDA
Crop
Profiles
for
Pecans
in
Georgia.
August
2001.
http://
pestdata.
ncsu.
edu/
cropprofiles/
docs/
GApecans.
html
Managing
Insect
and
Mite
Pests
of
Commercial
Pecans
in
Texas,
March
1998.
Texas
Agricultural
Extension
Service,
Texas
A&
M
University
System.
http://
insects.
tamu.
edu/
extension/
bulletins/
b­
1238.
html
5
Commercial
Pecan
Pest
Control
­
Diseases,
Insects,
and
Weeds.
2003.
Mississippi
State
University
Extension
Service.
http://
msucares.
com/
pubs/
publications/
p0461.
pdf
Pecan
Timelines.
May
2002.
Nicole
Zinn,
US
EPA/
OPP/
BEAD/
BAB.
6
APPENDIX
A
General
Timeline
of
Crop
Stages,
Worker
Activities,
and
Key
Pests
in
Pecans
in
the
East
Region
(
VA
to
FL,
west
to
LA).
¹
Jan
Feb
March
April
May
June
July
August
Sept
Oct
Nov
Dec
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Crop
Stage
Dormant
Budbreak
Pollination
Nut
elongation
+
expansion
Shell
hardening
Kernel
development
Shuck
split
Worker
Activities
Irrigation
Mowing
Harvest
Pruning/
Thinning
Insect
Pests
Pecan
leaf
scorch
mite
Typical
insecticide
app.

¹
The
horizontal
bars
represent
the
usual
range
of
time
when
the
events
may
occur
for
the
entire
crop.
These
times
are
variable
depending
on
variability
in
geography,

climate,
and
weather.
7
