1
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
Biological
and
Economic
Impact
Analysis
of
Methyl
Parathion
on
Sweetpotatoes
FROM:
Nikhil
Mallampalli,
Entomologist
Herbicide
and
Insecticide
Branch
Tim
Kiely,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THROUGH:
David
Brassard,
Senior
Entomologist
Arnet
Jones,
Chief
Herbicide
and
Insecticide
Branch
Arthur
Grube,
Senior
Economist
David
Widawsky,
Chief
Economic
Analysis
Branch
TO:
Laura
Parsons,
Chemical
Review
Manager
Susan
Lewis,
Chief
Reregistration
Branch
1
Special
Review
and
Reregistration
Division
(
7508C)

Peer
Review
Date:
August
21,
2002
SUMMARY
Methyl
parathion
is
used
on
sweetpotatoes
(
Ipomoea
batatas)
under
a
Special
Local
Needs
(
SLN)
label
in
Alabama,
Arkansas,
Louisiana,
Mississippi,
and
Texas.
The
main
target
pest
of
concern
in
Louisiana,
Mississippi
and
Alabama
is
the
sweetpotato
weevil.
There
is
zero
tolerance
for
weevil
infested
tubers,
and
these
states
have
quarantined
infested
sweetpotato
growing
regions
in
so­
called
"
red­
tag"
areas.
Frequent
insecticide
applications,
along
with
cultural
practices
intended
to
sanitize
2
fields
and
harvest,
are
required
for
the
harvest
from
the
"
red
tag"
areas
to
be
certified
as
"
weevil­
free".
In
all
the
states
that
have
the
SLN
label,
other
soil­
inhabiting
insects
are
also
controlled
by
methyl
parathion,
though
perhaps
to
a
lesser
extent
in
Arkansas
and
Texas.
These
include
larvae
of
the
whitefringed
beetle
and
cucumber
beetle,
which
also
damage
tubers
and
reduce
harvest
quality.
While
cultural
practices
will
probably
eliminate
the
danger
of
harvest
rejection
due
to
weevil
contamination,
the
loss
of
methyl
parathion
could
result
in
a
decrease
in
harvest
quality
from
these
regions,
since
it
would
create
a
gap
in
control
of
migrating
beetles
and
weevils
during
the
growing
season.
This
will
be
more
likely
after
risk
mitigation
and
concomitant
reductions
in
applications
go
into
effect
for
endosulfan,
which
is
also
used
for
the
same
purposes
as
methyl
parathion
in
sweetpotato.
These
impacts
may
be
particularly
acute
in
Alabama,
Louisiana,
and
Mississippi,
where
sweetpotatoes
appear
to
be
colonized
by
these
pests
more
frequently
during
the
growing
season.
For
these
insects,
only
phosmet
and
endosulfan
have
a
residual
activity
similar
to
that
of
methyl
parathion.
While
these
are
not
the
only
alternative
insecticides
available
to
growers,
BEAD
believes
that
growers
will
not
be
able
to
replace
all
of
the
methyl
parathion
applications
effectively
over
the
growing
season.
If
methyl
parathion
is
not
available
for
control
of
these
insects,
economic
analysis
suggests
that
growers
could
lose
as
much
as
$
1,106
in
per
acre
net
cash
returns,
and
total
losses
in
the
states
involved
could
be
as
high
as
$
17.3
million.
The
estimated
losses
arise
from
the
lower
price
received
for
the
sweetpotatoes
harvested
due
to
increased
pest
damage
without
methyl
parathion
available
for
use,
and
from
using
higher
cost
insecticides
in
place
of
methyl
parathion.

LIMITATIONS
AND
SCOPE
OF
ANALYSIS
The
scope
of
this
analysis
includes
an
examination
of
potential
regional­
level
impacts
associated
with
lack
of
availability
of
methyl
parathion
in
sweetpotato
production.
This
mitigation
scenario
is
in
response
to
the
high
health
risks
to
mixers,
loaders
and
applicators
as
identified
by
the
Health
Effects
Division
of
the
Office
of
Pesticide
Programs.
This
analysis
does
not
attempt
to
address
impacts
associated
with
mitigation
efforts
targeted
at
workers
reentering
fields
treated
with
methyl
parathion,
or
potential
mitigation
for
various
environmental
risks
(
i.
e.,
risk
mitigation
for
risks
to
terrestrial
plants
and
organisms
or
water
contamination).

There
are
limitations
to
this
assessment.
The
impacts
estimated
by
this
analysis
only
represent
potential
short­
term
 
1
to
2
years
 
impacts
on
the
sweetpotato
production
system.
Assumptions
about
yield
and
quality
losses
associated
with
the
various
scenarios
are
based
on
the
best
professional
judgement
of
BEAD
analysts
when
estimates
were
not
available
from
other
sources.
The
basis
for
these
assumptions
is
knowledge
acquired
from
reviewing
available
USDA
crop
profiles,
state
crop
production
guides,
discussions
with
university
extension
and
research
entomologists
knowledgeable
in
sweetpotato
production,
and
other
sources
listed.
Production
of
sweetpotato
is
a
very
complex
system
that
can
be
affected
by
many
parameters
(
e.
g.,
weather).
BEAD's
ability
to
quantitatively
capture
the
wide
array
of
events
that
could
unfold
given
each
hypothetical
scenario
listed
above
is
very
limited.
The
economic
analyses
are
based
on
crop
budgets
prepared
by
University
Extension
Specialists,
which
do
not
always
include
the
exact
combination
of
pesticides
considered
in
BEAD's
scenarios.
This
analysis
will
focus
solely
on
operation
costs,
ignoring
overhead
and
other
opportunity
costs,
which
can
be
difficult
to
measure
and
are
beyond
the
scope
of
this
exercise.
Thus,
net
cash
returns
overstate
actual
3
profits
to
the
grower.

CROP
PRODUCTION
AND
VALUE
There
are
an
average
of
90,400
acres
of
sweetpotatoes
harvested
per
year
in
the
U.
S.,
producing
nearly
675,000
tons
of
sweetpotatoes
valued
at
more
than
$
215
million.
Table
1
summarizes
sweetpotato
production
statistics
for
the
U.
S.
and
the
major
producing
states
and
regions.
The
major
states
of
production
are
North
Carolina,
Louisiana,
California
and
Mississippi.
Together
they
account
for
more
than
92%
of
total
U.
S.
sweetpotato
production.
The
major
U.
S.
production
region
is
the
Southern
Region,
which
produces
more
than
40%
of
total
U.
S.
sweetpotato
production.

Table
1.
Sweetpotato
Production
Statistics
by
State1
State
Area
Harvested
(
Acres)
Yield
(
tons
/
acre)
Production
(
tons)
Percent
of
Total
U.
S.
Production
Price
($/
ton)
Value
of
Production
($
1,000)

U.
S.
90,400
7.4
673,300
­­
322
217,000
Southern
Region
39,000
7.0
273,900
41%
307
84,200
AL
3,100
7.4
22,900
3%
332
7,600
LA
23,000
7.1
163,300
24%
283
46,200
MS
12,900
6.8
87,700
13%
347
30,400
CA
10,200
12.0
122,400
18%
555
67,900
NC
34,000
7.3
248,200
37%
224
55,600
TX
4,600
2.8
12,900
2%
335
4,300
Other
States
2
2,600
6.1
15,900
2%
316
5,000
1.
Based
on
USDA/
NASS
Agricultural
Statistics,
1998­
2000.
2.
Other
states
include:
AR
(
164
acres
harvested
in
1997),
GA,
NJ,
SC,
VA.

USE
AND
USAGE
OF
METHYL
PARATHION
ON
SWEETPOTATOES
The
estimated
usage
of
methyl
parathion
on
sweetpotatoes
is
summarized
in
Table
2.
Approximately
17%
of
the
U.
S.
sweetpotato
acreage
is
treated
with
methyl
parathion
and
nearly
17,000
pounds
of
methyl
parathion
are
applied.
The
states
where
methyl
parathion
is
being
used
on
sweetpotatoes
include
Alabama,
Louisiana
and
Mississippi.
Each
state
treats
an
estimated
40%
of
their
4
sweetpotato
acreage
with
methyl
parathion
(
see
Table
2).
The
estimated
usage
in
Mississippi
and
Alabama
is
based
on
usage
estimates
for
Louisiana
due
to
the
similarities
in
sweetpotato
target
pests
and
methyl
parathion
use
patterns
in
the
three
states.
The
available
data
do
not
indicate
that
methyl
parathion
is
used
on
sweetpotatoes
in
Arkansas
or
Texas.

Table
2.
Methyl
Parathion
Usage
on
Sweetpotatoes.

State
Acres
Harvested
Acres
Treated
Percent
Crop
Treated
Pounds
Active
Ingredient
Applied
U.
S.
90,400
15,640
1
17%
16,560
1
Southern
Region
39,000
15,640
1
40%
16,560
1
Alabama
3,100
1,240
40%
2
1,860
Louisiana
23,000
9,200
40%
2
6,900
Mississippi
12,900
5,200
40%
2
7,800
Source:
Personal
communication
with
A.
Hammond,
2002
(
Louisiana
only).
1.
Total
for
the
U.
S.
and
Southern
Region
based
on
the
sum
of
usage
for
three
states.
There
is
no
information
available
on
the
usage
of
methyl­
parathion
in
any
other
states.
2.
Estimates
of
percent
of
crop
treated
for
Mississippi
and
Alabama
are
based
on
estimates
of
usage
in
Louisiana.
Due
to
the
similarities
in
sweetpotato
target
pests
and
methyl
parathion
use
patterns
in
the
Mississippi,
Louisiana
and
Alabama,
usage
estimates
for
Mississippi
and
Alabama
are
based
on
usage
estimates
for
Louisiana.

INSECT
PESTS
TARGETED
BY
METHYL
PARATHION,
AND
POTENTIAL
ALTERNATIVES
In
sweetpotato,
methyl
parathion
is
available
only
in
Alabama,
Arkansas,
Louisiana,
Mississippi,
and
Texas
under
a
Special
Local
Needs
(
SLN)
registration.
It
is
used
to
control
the
sweetpotato
weevil
(
Colas
formicarius
elegantulus),
the
white­
fringed
beetle
(
Graphognathus
spp.),
and
the
cucumber
beetle
(
Diabrotica
spp.).
Of
these,
the
sweetpotato
weevil
is
arguably
the
most
critical
pest,
in
that
the
industry
requires
tubers
to
be
certified
free
of
this
introduced,
tropical
insect
if
the
harvest
originates
from
potentially
infested
regions
(
A.
Hammond,
personal
communication).
To
achieve
this
certification,
Louisiana,
Alabama,
and
Mississippi
(
where
weevil
populations
have
occurred
most
often)
have
designated
"
red­
tag"
areas
within
their
growing
regions
where
insecticide
sprays
must
be
made
at
7­
10
day
intervals
in
fields
where
weevil
adults
have
been
detected
in
pheromone
traps
that
growers
are
required
to
maintain
(
A.
Hammond
and
R.
Poret,
personal
communication).
In
Mississippi,
a
large
portion
of
the
sweetpotato
acreage
has
been
moved
to
the
northern
part
of
the
state,
which
is
not
under
quarantine
(
A.
Hammond,
personal
communication).
BEAD
believes
that
the
current
and
future
threat
posed
by
the
sweetpotato
weevil
is
highest
in
Louisiana,
where
a
significant
acreage
(
approximately
10,000
acres)
still
exists
in
the
quarantined
areas.
In
northern
parts
of
the
state,
spraying
for
weevils
is
done
if
4
or
more
weevils
are
found
in
a
trap
(
A.
Hammond,
personal
communication).
The
weevil
is
capable
of
causing
great
destruction
to
tubers,
both
by
direct
feeding
and
by
reducing
the
quality
of
the
yield,
which
tastes
bitter
even
after
weevils
have
left.
Both
adults
and
larvae
can
cause
5
damage
(
adults
can
also
reduce
yield
if
they
feed
uncontrolled
on
foliage).
However,
larvae
are
considered
the
most
injurious
stage;
even
low
numbers
can
reduce
sweetpotato
quality
and
marketable
yield
(
USDA
2001a).
They
can
also
be
serious
pests
of
stored
tubers,
and
thus
must
be
prevented
from
entering
the
harvest.

This
insect
persistently
occurs
south
of
a
line
that
roughly
parallels
Interstate
20
across
Louisiana
and
Mississippi.
Infestations
are
occasionally
found
as
far
as
20
miles
north
of
this
line.
The
insect
is
a
limiting
factor
in
commercial
sweetpotato
production
south
of
I­
20,
so
this
area
is
under
a
quarantine.
The
insect
is
the
most
economically
important
arthropod
pest
of
sweetpotatoes
worldwide
(
USDA
2001b).
Isolated
populations
have
also
been
found
in
Texas
and
along
the
Arkansas
border
(
NAPIS
2000).
Cultural
practices
can
often
suppress
or
prevent
weevil
infestations.
These
practices
include
removal
of
tubers
and
harvest
debris
from
fields,
which
removes
overwintering
sites
the
weevil
can
use,
and
preventive
spraying
of
storage
areas
with
phosmet
(
USDA
2001a,
b).
These
practices
usually
rid
the
harvest
of
weevil
contamination,
though
they
do
not
guarantee
that
tubers
will
not
be
damaged
during
the
growing
season
(
A.
Hammond,
personal
communication,
USDA
2001b).
In
southern
parts
of
Louisiana,
Alabama
and
Mississippi,
where
weevil
populations
are
highest,
the
presence
of
wild
host
plants
in
the
genus
Ipomoea
(
e.
g.,
morning­
glory)
appear
to
foster
more
frequent
infestation
of
sweetpotato
fields
during
the
growing
season
(
A.
Hammond,
personal
communication).

The
other
insects
targeted
are
also
potentially
serious
sources
of
damage.
Whitefringed
beetle
grubs
feed
on
roots
and
cause
irregular
scars
and
holes
in
tubers.
Cucumber
beetle
grubs
eat
small
holes
in
tubers
and
form
irregular
cavities
under
the
skin
(
Averre
et
al.
1997).
White­
fringed
beetle,
cucumber
beetles,
and
weevils
all
feed
on
foliage
as
adults,
though
it
is
the
larvae
that
do
the
economically
significant
damage.
However,
this
habit
means
they
can
be
affected
by
foliar
insecticide
sprays.

Foliar
insecticide
sprays
for
these
insects
are
made
after
scouting
reveals
the
presence
of
adults
or
larvae,
a
practice
common
to
all
the
sweetpotato
production
in
these
states.
No
effective
biological
control
agents
are
commercially
available
for
any
of
the
insects
targeted
by
methyl
parathion
(
USDA
2001b).
There
is
some
research
underway
that
is
examining
the
feasibility
of
soil­
inhabiting
nematodes
for
use
against
the
grubs,
but
these
organisms
are
unlikely
to
substitute
for
insecticides
in
the
near
future.
Adult
weevils
and
beetles
are
probably
preyed
upon
by
birds
and
large,
predatory
insects,
but
BEAD
found
no
evidence
that
these
are
effective
control
agents.

Endosulfan,
phosmet,
and
carbaryl
are
all
sometimes
used
for
the
same
purpose
as
methyl
parathion
in
sweetpotatoes.
Endosulfan
and
phosmet
are
approximately
equal
to
methyl
parathion
in
effectiveness
against
the
target
insects
mentioned
here
(
Story
et
al.
2001),
but
frequent
sprays
of
multiple
chemicals
are
often
required
to
suppress
these
insects
across
the
growing
season
(
typically
May
to
July).
Of
these,
methyl
parathion
appears
to
be
the
longest
lasting
foliar
insecticide
available
(
Hammond
et
al.
2001,
Seal
2001,
Story
et
al.
2001).
Thus,
endosulfan
and
phosmet
may
not
be
able
to
adequately
substitute
for
methyl
parathion,
despite
their
comparable
efficacy.
Louisiana
and
Mississippi
also
acquired
bifenthrin,
a
synthetic
pyrethroid,
under
an
emergency
exemption
this
year.
However,
only
two
applications
are
allowed
per
season,
and
BEAD
is
unable
to
assess
its
efficacy
relative
to
that
of
methyl
parathion.

It
should
also
be
noted
that
carbaryl
is
often
reserved
for
use
against
other
insect
pests
(
e.
g.,
6
leafhoppers)
that
can
unexpectedly
become
problems
during
the
growing
season
(
USDA
2001b).
The
number
of
methyl
parathion
applications
per
season
used
across
Louisiana
is
estimated
to
be
4
­
8,
with
8
being
more
typical
in
the
"
red­
tag"
areas
(
A.
Hammond,
R.
Poret,
personal
communication).
Since
growing
conditions
and
pest
pressures
are
similar,
BEAD
assumes
a
similar
level
of
methyl
parathion
use
in
Alabama
and
Mississippi.
Since
the
growing
season
is
typically
12
weeks
long
and
foliar
insecticidal
sprays
are
usually
made
on
a
weekly
basis
(
A.
Hammond,
R.
Poret,
personal
communication),
these
figures
suggest
that
methyl
parathion
forms
the
largest
component
of
these
insecticide
applications.

BIOLOGICAL
IMPACTS
OF
ELIMINATING
METHYL
PARATHION
IN
SWEETPOTATO
PRODUCTION
BEAD
believes
there
may
be
an
increase
in
tuber
damage
in
southern
parts
of
Alabama,
Louisiana,
and
Mississippi
due
to
sweetpotato
weevil
damage,
if
methyl
parathion
is
removed
from
the
set
of
insecticides
used
to
manage
this
insect.
Reductions
in
quality
will
probably
also
occur
in
most
of
the
other
sweetpotato
growing
regions
due
to
diminished
control
of
white­
fringed
and
cucumber
beetle
grubs.
In
general,
this
would
result
in
more
of
the
harvest
being
assigned
sub­
premium
grades,
which
fetch
much
lower
prices
than
top­
graded
tubers.

Populations
of
the
white­
fringed
and
cucumber
beetles
appear
to
be
on
the
rise
in
sweetpotatoes
in
Louisiana,
Alabama,
and
Mississippi.
They
are
often
major
pests
in
these
states
(
USDA
2001b).
This
may
be
due
to
an
increase
in
nearby
soybean
and
pasture
acreage
(
A.
Hammond,
personal
communication).
These
areas
provide
good
habitat
for
fostering
large
numbers
of
these
insects,
which
are
highly
mobile
as
adults
and
easily
move
into
soybean
plants
to
feed
and
lay
eggs.

If
methyl
parathion
use
is
unavailable,
growers
will
be
forced
to
turn
to
some
combination
of
the
available
alternatives.
BEAD
believes
that
they
will
probably
increase
their
use
of
carbaryl,
endosulfan,
and
phosmet.
Endosulfan
and
phosmet
will
be
used
as
much
as
possible
since
they
are
known
to
be
similar
to
methyl
parathion
in
terms
of
efficacy.
Phosmet
can
only
be
applied
a
maximum
of
five
times
per
season.
Endosulfan
use
will
also
be
reduced
from
three
to
two
applications
per
season
due
to
risk
mitigation
included
in
its
recent
reregistration.
This
will
create
a
need
for
additional
use
of
another
insecticide.
For
this,
growers
will
probably
use
carbaryl
(
despite
some
evidence
of
lower
efficacy),
because
they
are
familiar
with
the
product
and
can
target
sporadic
infestations
of
other
insects
also
on
its
label.
Furthermore,
this
would
allow
some
rotation
of
insecticidal
chemistries
to
offset
resistance
evolution
in
the
insect
pests.
Since
this
insecticide
combination
is
not
likely
to
offer
the
same
level
of
control
as
methyl
parathion,
BEAD
concludes
an
increase
in
tuber
damage
is
probable.

Methyl
parathion
use
in
Texas
and
Arkansas
is
either
currently
nonexistent
or
at
a
low
level
that
does
not
warrant
formal
reporting
(
see
Table
2).
Texas
extension
service
publications
indicate
that
soilinhabiting
grubs
(
including
white­
fringed
and
cucumber
beetles)
are
usually
kept
under
adequate
control
with
the
application
of
chlorpyrifos
to
the
ground
at
planting
(
Holloway
et
al.
2000).
However,
these
publications
do
list
methyl
parathion
also
as
an
alternative
insecticide
option
for
beetle
adults,
grubs,
and
other
foliage­
feeding
insects
(
Sparks
1997,
Holloway
et
al.
2000).
7
If
populations
of
these
insects
increase
in
the
future,
growers
in
this
state
may
also
need
to
rely
more
heavily
on
methyl
parathion.
Since
Arkansas
sweetpotato
habitat
and
growing
conditions
are
likely
to
be
similar
to
that
of
Texas,
BEAD
presumes
that
the
situation
regarding
these
insects
is
likely
to
be
similar
also.
Soybean
is
widely
grown
in
the
same
areas
as
sweetpotato
in
both
states,
so
an
increase
in
populations
of
these
insects
remains
a
possibility.
The
other
target
of
methyl
parathion
applications,
the
sweetpotato
weevil,
is
rarely
reported
in
these
states.
Therefore,
BEAD
believes
it
will
not
increase
in
importance
as
a
pest
in
these
regions
if
this
insecticide
is
restricted.

ECONOMIC
IMPACTS
OF
ELIMINATING
METHYL
PARATHION
IN
SWEETPOTATO
PRODUCTION
The
per
acre
dollar
impact
of
the
unavailability
of
methyl
parathion
on
sweetpotatoes
is
estimated
in
Table
3.
As
described
above,
impacts
are
expected
in
the
Southern
Region
of
the
U.
S.,
which
includes
the
states
of
Alabama,
Louisiana,
and
Mississippi.
Methyl
parathion
is
critical
for
the
control
of
sweetpotato
weevil
and
white­
fringed
and
cucumber
beetles
in
this
region.
Table
3
lists
the
production,
price,
gross
revenues,
operating
costs
and
net
cash
returns
for
sweetpotatoes
in
the
Southern
Region
for
two
scenarios
(
the
"
base"
and
"
alternative"
scenarios),
and
the
percentage
change
in
each
of
these
items
between
the
two
scenarios.
The
base
scenario
assumes
that
methyl
parathion
is
still
available
for
use
on
sweetpotatoes,
and
the
alternative
scenario
assumes
that
methyl
parathion
is
not
available
for
use
on
sweetpotatoes.
Under
the
alternative
scenario,
it
is
assumed
that
without
methyl
parathion
available
for
use,
growers
would
apply
some
combination
of
carbaryl,
endosulfan
and
phosmet
in
an
attempt
to
control
the
pests
targeted
with
methyl
parathion
applications,
and
to
avoid
a
complete
loss
of
the
crop.
Impacts
are
measured
in
terms
of
the
percentage
change
in
per
acre
net
cash
returns
between
the
base
and
alternative
scenarios,
where
per
acre
net
cash
returns
are
equal
to
per
acre
gross
revenues
minus
per
acre
total
operating
costs.

Losses
in
sweetpotato
yields
in
the
Southern
Region
are
not
expected
if
methyl
parathion
is
not
available
for
use.
However,
if
methyl
parathion
is
unavailable
on
sweetpotatoes,
growers
in
the
Southern
Region
could
face
reductions
in
the
quality
of
their
harvested
sweetpotatoes
due
to
increased
pest
damage
as
a
result
of
inadequate
season­
long
control
of
sweetpotato
weevils
and
white­
fringed
and
cucumber
beetles.
The
quality
of
the
sweetpotatoes
harvested
could
drop
from
U.
S.
one
to
U.
S.
two
grade,
which
carries
with
it
a
50%
drop
in
the
price
received.
The
price
received
would
fall
from
$
308
per
ton
to
$
154
per
ton,
and
gross
revenues
would
decline
to
$
1,078
per
acre
from
$
2,156
per
acre
(
see
Table
3).

Without
methyl
parathion
available
for
use
on
sweetpotatoes,
growers
in
the
Southern
Region
could
also
face
an
increase
of
$
28
per
acre
(
or
140%)
in
pesticide
control
costs
due
to
the
increased
cost
of
the
alternatives
to
methyl
parathion
for
the
control
of
sweetpotato
weevils
and
white­
fringed
and
cucumber
beetles
(
see
Table
3).
The
analysis
assumes
that
at
least
four
applications
of
methyl
parathion
are
made
per
season
to
control
these
pests
in
the
Southern
Region,
and
that
four
applications
of
a
combination
of
carbaryl,
phosmet,
and
endosulfan
would
be
made
to
replace
methyl
parathion.
(
Since
phosmet
is
the
most
expensive
of
the
three
alternatives
to
methyl
parathion,
we
assume
that
no
more
than
two
of
the
applications
would
be
made
with
phosmet).
8
The
$
28
per
acre
increase
in
pesticide
control
costs
would
result
in
a
2%
increase
in
total
per
acre
operating
costs.
This
increase
in
per
acre
costs
when
combined
with
the
decline
in
per
acre
gross
revenues
of
$
1,078,
results
in
a
decline
in
per
acre
net
cash
returns
of
180%.
Per
acre
net
cash
returns
would
decline
from
$
615
per
acre
to
net
losses
of
$
491
per
acre
(
see
Table
3).

This
assessment
is
a
worst
case
scenario.
More
than
likely,
not
every
sweetpotato
harvested
on
each
acre
would
suffer
losses
in
grade,
and
not
every
acre
harvested
would
incur
increased
insect
control
costs.
However,
in
the
worst
case,
without
the
use
of
methyl
parathion,
growers
could
face
these
per
acre
losses
and
cost
increases.

Table
3.
Per
Acre
Gross
Returns,
Production
Costs
and
Net
Returns
to
Sweetpotato
Growers
in
the
Southern
U.
S.
with
In­
season
Control
of
Sweetpotato
Weevils
and
White­
fringed
and
Cucumber
beetles.

Base
Scenario:

methylparathion
Alternative:

carbaryl/
phosmet
/
endosulfan
%
Change
Between
Base
and
Alternative
Scenarios
production
(
tons/
acre)
7
7
0%

price
($/
ton)
308
154
­
50%

gross
revenues
($/
acre)
2,156
1,078
­
50%

insecticide
costs
($/
acre)

methyl­
parathion
1
carbaryl/
phosmet/
endosulfan
2
20
48
140%

other
insecticides
53
53
other
operating
costs
($/
acre)
1,468
1,468
total
operating
costs
($/
acre)
1,541
1,569
2%

net
cash
returns
($/
acre)
615
­
491
­
180%

Source:
USDA,
Auburn
University
and
Alabama
A&
M
University,
Louisiana
State
University,
Mississippi
State
University.

1.
The
estimated
cost
of
methyl
parathion
is
$
5
per
acre.
The
assessment
assumes
an
average
of
four
applications
of
methyl
parathion
per
acre
per
season
to
control
sweetpotato
weevil
and
white­
fringed
and
cucumber
beetles.

2.
The
estimated
cost
of
carbaryl
and
endosulfan
is
$
9
per
acre,
and
phosmet
is
$
15
per
acre.
The
assessment
assumes
two
applications
of
a
combination
of
carbaryl
and
endosulfan
and
two
applications
of
phosmet
to
replace
the
four
applications
of
methyl
parathion.

The
impacts
if
methyl
parathion
is
not
available
for
sweetpotato
production
in
Alabama,
9
Louisiana,
and
Mississippi,
as
well
as
in
the
Southern
Region,
are
estimated
in
Table
4.
An
estimated
40
%
of
the
acreage
grown
in
each
state
in
the
Southern
Region
is
treated
with
methyl
parathion
for
the
control
of
sweetpotato
weevils
and
white­
fringed
and
cucumber
beetles,
and
the
impact
as
described
above
is
assumed
to
occur
on
every
treated
acre.
This
results
in
a
total
impact
ranging
from
$
1.4
million
in
Alabama
to
$
10.2
million
in
Louisiana.
Losses
for
the
Southern
Region
could
be
as
high
as
$
17.3
million,
which
is
20
%
of
the
total
value
of
sweetpotato
production
in
the
region
(
see
Table
4)
(
and
8
%
of
the
total
value
of
sweetpotato
production
in
the
U.
S.).

As
mentioned
above,
this
assessment
is
a
worst
case
scenario.
It
is
not
expected
that
every
acre
previously
treated
with
methyl
parathion
would
suffer
these
losses
without
methyl
parathion,
but
information
was
not
available
at
the
time
of
the
assessment
to
indicate
the
likelihood
of
the
losses
per
farm.
These
estimated
losses
serve
as
an
upper
bound
of
the
impacts
of
the
lack
of
availability
of
methyl
parathion
on
sweetpotatoes.

Table
4.
State
and
Total
Impacts
of
No
Longer
Having
Methyl
Parathion
Available
for
Use
on
Sweetpotato
in
the
Southern
Region.

State
Acres
Impacted1
Cost
Increase
($/
acre)
2
Gross
Revenue
Decrease
($/
acre)
3
Total
Impact4
($
1000)
Total
value
of
Production
($
1000)
Total
Impact
as
a
%
of
Total
Value
of
Production
Alabama
1,240
28
1,078
1,371
7,600
18%

Louisiana
9,200
28
1,078
10,175
46,200
22%

Mississippi
5,200
28
1,078
5,751
30,400
19%

Southern6
Region
15,640
28
1,078
17,297
84,200
20%

1.
Acres
Impacted
is
the
number
of
acres
treated
in
the
state
(
see
Table
2).

2.
Cost
Increase
is
an
estimate
of
the
increase
in
production
costs
due
to
increases
in
the
cost
of
chemical
control
(
see
Table
3).

3.
Gross
Revenue
Decrease
is
the
estimated
decline
in
per
acre
gross
revenues
due
to
a
reduction
in
the
quality
of
the
sweetpotatoes
harvested
(
see
Table
3).

4.
Total
impact
is
equal
to
the
acres
impacted
multiplied
by
the
sum
of
the
per
acre
cost
increase
and
the
per
acre
gross
revenue
decrease
(
e.
g.
the
total
impact
in
Alabama
=
(
1,240
acres)
x
(
28
+
1,078)).

5.
Total
Impact
as
a
%
of
Total
Value
of
Production
is
equal
to
the
total
impact
divided
by
the
total
value
of
production.

6.
The
Southern
Region
impact
is
a
sum
of
impacts
in
the
3
states
listed.
10
IMPACT
SUMMARY
Methyl
parathion
is
critical
for
the
control
of
the
sweetpotato
weevil
and
white­
fringed
and
cucumber
beetles
on
sweetpotatoes
in
the
Southern
Region
of
the
U.
S.
(
Louisiana,
Alabama
and
Mississippi).
If
it
is
unavailable
for
use
in
sweetpotatoes,
growers
in
the
Southern
Region
could
face
losses
of
up
to
$
1,106
in
per
acre
net
cash
returns
from
losses
in
the
quality
of
the
sweetpotatoes
harvested
(
i.
e.,
a
reduction
in
the
price
received),
and
increases
in
the
cost
of
pest
control
from
using
higher
cost
alternatives
to
methyl
parathion
in
an
effort
to
avoid
complete
crop
loss
from
infestations
of
sweetpotato
weevils
and
white­
fringed
and
cucumber
beetles.
Losses
in
the
Southern
Region
could
be
as
high
as
$
17.3
million.

SOURCES
Auburn
University
and
Alabama
A&
M
University.
Sweetpotatoes:
Estimated
Costs
and
Returns
Per
Acre.
1999.

Averre,
C.
W.,
K.
A.
Sorenson,
and
L.
G.
Wilson.
1997.
Know
and
Manage
Sweetpotato
Pests.
North
Carolina
Agricultural
Extension
Service,
Raleigh,
NC.

Dr.
Abner
Hammond.
Professor
and
Specialist.
Department
of
Entomology,
Louisiana
State
University,
Baton
Rouge,
LA.

Hammond,
A.
M.,
R.
Story,
A.
Diagne,
and
M.
J.
Murray.
2001.
Residual
activity
of
foliar
applied
insecticides
on
sweetpotato
insects,
1997.
Arthropod
Management
Tests,
Vol
26,
article
#
L9.

Holloway,
R.
L.,
K.
D.
Hale,
and
D.
T.
Smith.
2000.
Texas
Crop
Profile:
Sweetpotatoes.
Pub.
E­
22
of
the
Texas
Agricultural
Extension
Service,
Texas
A&
M
University,
College
Station,
TX.

Louisiana
State
University.
Projected
Costs
for
Selected
Louisiana
Vegetable
Crops:
1997
Season.

Mississippi
State
University.
Vegetables:
1999
Planning
Budgets.

NAPIS
(
National
Agricultural
Pest
Information
System)
2000.
Database
available
on
the
Web
at:
http://
www.
ceris.
purdue.
edu/
napis/
pests/
spw/
index.
html.

National
Center
for
Food
and
Agricultural
Policy.
U.
S.
Pesticide
Use
Database.

Mr.
Ray
Poret,
President.
Louisiana
Sweetpotato
Growers
Association.

Seal,
D.
2001.
Effectiveness
of
various
insecticides
in
controlling
the
sweetpotato
weevil,
1999.
Arthropod
Management
Tests,
Vol.
26,
article
#
E83.

Sparks,
A.
N.
1997.
Texas
Guide
for
Controlling
Insects
on
Commercial
Vegetable
Crops.
Pub.
B­
1305
of
the
Texas
Agricultural
Extension
Service,
Texas
A&
M
University,
College
Station,
TX.

Story,
R.,
A.
M.
Hammond,
A.
Diagne,
and
M.
J.
Murray.
2001.
Residual
activity
of
foliar
applied
insecticides
on
sweetpotato
insects,
1996.
Arthropod
Management
Tests,
Vol
26,
article
#
L10.

USDA
1999.
Crop
Profile
for
Sweetpotatoes
in
Mississippi.
Available
on
the
Web
at:
http://
www.
pmcenters.
org/
CropProfiles/
index.
html.
11
USDA
2001a.
Crop
Profile
for
Sweetpotatoes
in
Louisiana.
Available
on
the
Web
at:
http://
www.
pmcenters.
org/
CropProfiles/
index.
html.

USDA
2001b.
Pest
Management
Strategic
Plan
for
Sweetpotatoes
in
Alabama,
Louisiana,
Mississippi,
New
Jersey,
North
Carolina,
and
South
Carolina.
USDA/
OPMP
workshop
publication.
Available
at
http://
pestdata.
ncsu.
edu/
pmsp/
index.
cfm.

USDA.
2001
Agricultural
Statistics.
