Document ID: EPA-HQ-OAR-2003-0230-0099
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-06-10T04:00Z

U.
S.
A.
TOBACCO
NURSERY
TRAYS
TRANSPLANT
TRAYS
USED
IN
FLOAT
BED
CULTURE
TABLE
OF
CONTENTS
Introduction
................................................................................................................................
2
Critical
Need
for
Methyl
Bromide...............................................................................................
2
Response
to
Questions
from
MBTOC/
TEAP
..............................................................................
2
Definitions
..................................................................................................................................
6
References
..................................................................................................................................
7
LIST
OF
TABLES
Table
1.
Region,
Key
Pests,
and
Critical
Need
for
Methyl
Bromide.
..........................................
2
Table
2.
Historical
Use
of
Methyl
Bromide
in
the
Seedling
Transplant
Tray
Sector....................
4
Table
3.
Calculation
of
the
Nominated
Amount
of
Methyl
Bromide
in
the
Seedling
Transplant
Tray
Sector...........................................................................................................................
4
Page
2
INTRODUCTION
The
U.
S.
nursery
tray
CUE
nomination
requests
use
of
a
small
amount
of
methyl
bromide
(
MB)
to
allow
continued
use
of
a
float
bed
transplant
system
instead
of
field
grown
transplants.
Growers
in
North
Carolina,
anticipating
a
need
to
reduce
their
reliance
on
MB,
switched
to
float
bed
cultivation
several
years
ago,
resulting
in
a
reduction
in
MB
consumption
by
over
99%
as
compared
to
field
grown
transplants.
Alternatives
that
would
allow
phase
out
the
final
1%
of
MB
use
in
this
sector
are
not
deemed
to
be
feasible
at
this
time.
The
only
fungicide
registered
for
use
on
tobacco
transplants,
etridiazole,
has
not
been
shown
to
be
effective
against
Rhizoctonia
spp.,
which
is
one
of
the
major
target
pests
in
transplant
trays.

Table
1.
REGION,
KEY
PESTS,
AND
CRITICAL
NEED
FOR
METHYL
BROMIDE.

U.
S.
Region
/
States
Key
Pests
Critical
Need
for
Methyl
Bromide
Tobacco
Growers
Association
of
North
Carolina
(
CUE
02­
0025)
Diseases:
Rhizoctonia
spp.;
Pythium
spp.;
Phytophthora
spp.
There
are
no
registered
alternatives
that
can
control
the
pathogens
in
polystyrene
transplant
trays.
MB
applications
in
transplant
trays
are
typically
made
using
98:
2
mixtures
with
chloropicrin
under
plastic
tarps.
The
quantity
nominated
represents
a
99%
reduction
in
the
amount
of
MB
used
in
the
past
for
field
grown
transplants.

CRITICAL
NEED
FOR
METHYL
BROMIDE
The
North
Carolina
tobacco
seedling
industry
has
reduced
its
MB
use
to
1%
of
its
previous
use
by
implementing
a
float
bed
transplant
system
instead
of
field­
grown
transplants.
Prior
to
the
1990s,
tobacco
transplants
were
produced
in
outdoor
soil
plant
beds,
which
were
fumigated
with
MB
at
a
rate
of
6
to
8
kg
of
active
ingredient
(
a.
i.)
per
165
m2,
sufficient
for
establishing
one
hectare
of
tobacco
(
6­
7
lb
per
720
ft2
to
establish
one
acre).
If
bed
fumigation
were
still
in
use,
it
would
require
over
454,500
kg
(
1,000,000
lb)
of
MB
to
fumigate
sufficient
plant
beds
for
2002
levels
of
tobacco
production
in
North
Carolina,
the
major
producing
state.
During
the
1990s,
however,
direct­
seeded
systems
were
developed
to
raise
tobacco
seedlings
in
a
float
system
in
greenhouses
and
the
system
was
rapidly
adopted
throughout
North
Carolina.

The
float
bed
transplant
system
is
a
modified
hydroponic/
subsurface
watering
system.
Each
tray
contains
200­
338
cells
with
each
cell
containing
one
seedling.
The
use
of
polystyrene
trays
is
necessary
because
the
trays
must
float
in
the
nutrient
media.
After
plants
are
transplanted,
trays
are
disinfected
and
stored
until
next
season.
The
polystyrene
trays
are
stacked,
tarped
and
then
MB
is
applied
at
a
rate
of
about
1
kg
per
21
m3
(
3
lb
per
1000
ft2).
At
the
current
application
rate,
making
the
adjustments
discussed
in
Table
3,
it
will
take
1,323
kg
(
3,000
lb)
of
MB
to
sterilize
the
trays
needed
to
produce
sufficient
transplants
for
the
tobacco
crop
of
North
Carolina.
This
is
1
percent
of
the
amount
that
would
have
been
needed
to
raise
tobacco
seedlings
under
the
previous
field
bed
production
system.

RESPONSE
TO
QUESTIONS
FROM
MBTOC/
TEAP
1.
"
MBTOC
noted
that
alternatives
are
in
common
use
in
similar
circumstances
in
several
countries.
These
alternatives
include
chlorine,
irradiation,
fungicides,
steam,
and
quaternary
ammonium
compounds
Page
3
The
United
States
has
not
found
evidence
that
alternatives
are
in
common
use
in
similar
circumstances.
Statements
in
the
literature
about
the
effectiveness
of
alternatives
pertain
to
one
of
two
situations:
either
hard
plastic
trays
are
being
used
rather
that
the
floating
system
of
polystyrene
trays,
or
fungicides
are
registered
in
those
countries
that
are
effective
against
these
pathogens.
For
the
system
of
seedling
production
in
current
use,
the
suggested
alternatives
are
not
effective.
Specifically,

Chlorine:
The
United
States
finds
that
liquid
chlorine
does
not
penetrate
the
spaces
within
the
polystyrene
transplant
trays
to
kill
the
fungal
pathogens.
Chlorine
will
penetrate
the
trays
with
a
surfactant
added.
Unfortunately,
with
a
surfactant
the
liquid
cannot
be
drained
from
the
spaces
within
the
tray
resulting
in
plant
phytotoxicity
and/
or
sinking
of
the
transplant
trays.
Also,
salt
residues
can
cause
serious
problems
resulting
in
plant
kills
(
personal
communication,
Thomas
A.
Melton,
Ph.
D.,
Philip
Morris
Professor,
North
Carolina
State
University).

Irradiation:
Currently
no
producers
of
tobacco
seedlings
in
the
United
States
use
irradiation
to
sterilize
their
trays.
The
United
States
has
been
unable
to
find
data
indicating
that
irradiation
is
effective
and
does
not
damage
the
polystyrene
trays.
Additionally,
the
United
States
estimates
that
the
cost
of
irradiation
plus
transportation
to
the
facility
is
extremely
high,
$
100­
1,000/
kg
of
MB
replaced.

Fungicides:
Etridiazole
has
recently
been
registered,
under
the
trade
name
Terrazole,
to
control
pathogens
in
tobacco
float
beds.
It
is
applied
in
the
water
upon
which
the
plastic
beds
float
about
two
to
eight
weeks
after
seeding.
However,
it
has
not
been
shown
to
be
effective
against
Rhizoctonia
spp.,
which
is
one
of
the
major
target
pests
in
transplant
trays
(
personal
communication,
Thomas
A.
Melton,
Ph.
D.,
Philip
Morris
Professor,
North
Carolina
State
University).
Etridiazole
did
not
provide
adequate
control
of
Phytophthora
spp.,
a
cause
of
damping
off
in
tobacco
plants
(
Nesmith
2003).
No
other
fungicides
are
labeled
for
use
on
tobacco
transplants
in
the
United
States.

Steam:
Some
studies
suggest
that
the
difference
between
effective
steam
sterilization
of
the
polystyrene
trays
and
melting
of
the
trays
is
2
degrees
Celsius.
This
method
has
not
been
successful
on
the
commercial
scale
because
of
problems
maintaining
sufficient
control
of
the
steam
to
hold
the
proper
temperature
for
the
prescribed
amount
of
time
to
sterilize
the
trays
without
damage
to
the
trays
(
personal
communication,
Thomas
A.
Melton,
Ph.
D.,
Philip
Morris
Professor,
North
Carolina
State
University).

Quaternary
Ammonia:
The
U.
S.
finds
that
liquid
quaternary
ammonium
compounds
do
not
penetrate
the
spaces
within
the
polystyrene
transplant
trays
to
kill
the
fungal
pathogens.
Also,
salt
residues
can
cause
serious
problems
resulting
in
plant
kills.
Quaternary
ammonium
compounds
work
better
with
a
surfactant
added.
Unfortunately,
with
a
surfactant
the
liquid
cannot
be
drained
from
the
spaces
within
the
tray
resulting
in
plant
phytotoxicity
and/
or
sinking
of
trays
(
personal
communication,
Thomas
A.
Melton,
Ph.
D.,
Philip
Morris
Professor,
North
Carolina
State
University).
Page
4
TABLE
2.
HISTORICAL
USE
OF
METHYL
BROMIDE
IN
THE
SEEDLING
TRANSPLANT
TRAY
SECTOR
Historical
Use
Average
Use
Rates
(
kg/
1,000
m3)
Total
Amount
(
kg)
Volume
Treated
(
1,000
m3)

1997
47
3,397
72
1998
47
2,733
58
1999
47
2,656
56
2000
47
2,345
50
2001
48
3,294
69
*
Acres
planted
in
U.
S.
and
percent
of
U.
S.
acreage
requested
is
not
available.
Information
taken
from
CUE
application.

TABLE
3.
CALCULATION
OF
THE
NOMINATED
AMOUNT
OF
METHYL
BROMIDE
IN
THE
SEEDLING
TRANSPLANT
TRAY
SECTOR.

Calculation
of
Nominated
Amount
0025
 
Tobacco
Growers
Association
of
North
Carolina
Volume
(
1,000
m3)
98
%
of
Regional
Volume
(
1,000
m3)(
A)
Not
Available
Applicant
Request
for
2005
Kilograms
(
kg)
of
MB
4,612
Double
Counted
Volume
(
1,000
m3)(
B)
 
Growth
/
Increasing
Production
(
1,000
m3)(
C)
29
Quarantine
and
Pre­
Shipment
Volume
(
1,000
m3)(
D)
41
Adjustments
to
Request
Adjusted
Volume
Requested
(
1,000
m3)(
E)
27
Key
Pest
Impacts
(%)(
F)
100
Regulatory
Impacts
(%)(
G)
0
Soil
Impacts
(%)(
H)
0
Impacts
to
Adjusted
Hectares
Total
Combined
Impacts
(%)(
I)
100
Qualifying
Volume
(
1,000
m3)(
J)
27
Use
Rate
(
kg/
1,000
m3)(
K)
47
CUE
Amount
Nominated
(
kg)(
L)
1,291
%
Reduction
from
Initial
Request
(
M)
72
Sum
of
all
CUE
Nominations
in
Sector
(
kg)(
N)
1,291
Multiplier
for
Margin
of
Error(
O)
1.0244
Total
U.
S.
Sector
Nomination
(
kg)(
P)
1,323
Page
5
Footnotes
for
Table
3:

Values
may
not
sum
exactly
due
to
rounding.

A.
Percent
of
regional
volume
is
the
volume
in
the
applicant's
request
divided
by
the
total
volume
used
in
the
region
covered
by
the
request.
This
information
is
unavailable
for
this
sector
B.
Double
counted
volume
is
the
volume
counted
in
more
than
one
application.
There
was
no
double
counting
in
this
sector.
C.
Growth
/
increasing
production
volume
is
the
amount
of
volume
requested
by
the
applicant
that
is
greater
than
that
historically
treated
or
treated
at
a
higher
use
rate.
D.
Quarantine
and
pre­
shipment
(
QPS)
volume
is
the
volume
in
the
applicant's
request
subject
to
QPS
treatments
and
therefore
excluded
from
this
CUN.
E.
Adjusted
volume
requested
is
the
volume
in
the
applicant's
request
minus
the
volume
affected
by
double
counting,
growth
/
increasing
production,
and
quarantine
and
pre­
shipment.
F.
Key
pest
impacts
is
the
percent
(%)
of
the
requested
volume
with
moderate
to
severe
pest
problems.
Key
pests
are
those
that
are
not
adequately
controlled
by
MB
alternatives.
Rhizoctonia
spp.
And
phytophtora
spp.
affect
the
entire
tobacco
seedling
crop
and
are
not
controlled
by
alternatives.
G.
Regulatory
impacts
is
the
percent
(%)
of
the
requested
volume
where
alternatives
cannot
be
legally
used
(
e.
g.,
buffer
zones
or
township
caps).
H.
Soil
impacts
is
the
percent
(%)
of
the
requested
volume
where
alternatives
cannot
be
used
due
to
soil
type
(
e.
g.,
heavy
clay
soils
may
not
show
adequate
performance
of
some
alternatives).
I.
Total
combined
impacts
is
the
percent
(%)
of
the
requested
volume
where
alternatives
cannot
be
used
due
to
key
pest,
regulatory,
or
soil
impacts.
In
each
case
the
total
area
impacted
is
the
area
which
is
impacted
by
one
or
more
of
the
individual
impacts.
For
each
application
the
assessment
was
made
by
biologists
familiar
with
the
specific
situation
and
able
to
make
judgments
about
the
extent
of
overlap
of
the
impacts.
For
example,
in
some
situations
the
impacts
are
mutually
exclusive
 
in
heavy
clay
soils
1,3D
will
not
be
effective
because
it
does
not
penetrate
these
soils
evenly,
but
none
of
the
heavy
soil
areas
will
be
impacted
by
township
(
regulatory)
caps
because
no
one
will
use
1,3D
in
this
situation,
so
this
soils
impact
must
be
added
to
the
township
cap
regulatory
impact
in
a
California
application.
In
other
words
there
is
no
overlap.
In
other
situations
one
area
of
impact
might
be
a
subset
of
another
impact.
In
these
cases,
the
combined
impact
is
equal
to
the
largest
individual
impact.
J.
Qualifying
volume
is
calculated
by
multiplying
the
adjusted
volume
requested
by
the
total
combined
impacts.
K.
Use
rate
is
the
requested
use
rate
for
2005.
This
rate
may
be
adjusted
downward
based
on
historical
use
patterns.
L.
CUE
amount
nominated
is
calculated
by
multiplying
the
qualifying
volume
by
the
use
rate.
M.
Percent
reduction
from
initial
request
is
the
percentage
of
the
initial
request
that
did
not
qualify
for
the
CUE
nomination.
N.
Sum
of
all
CUE
nominations
in
sector.
Self­
explanatory.
O.
Multiplier
for
margin
of
error.
This
amount
is
one
percentage
point
of
the
original
(
1991)
baseline
amount.
This
factor
is
intended
to
compensate
for
the
compounding
influence
of
using
the
low
end
of
the
range
for
all
input
parameters
in
the
calculation
of
the
US
nomination
(
i.
e.,
using
the
lowest
percent
impact
on
the
lowest
number
of
acres
at
the
lowest
dosage
is
likely
to
result
in
values
that
are
unrealistically
too
small).
The
U.
S.
nominated
included
some
sectors
for
100%
of
the
amount
requested,
therefore
the
portion
of
the
multiplier
from
these
sectors
were
added
equally
across
all
other
sectors
resulting
in
a
final
multiplier
of
1.0244,
or
a
2.44%
increase
from
the
calculated
amount,
to
these
sectors.
P.
Total
U.
S.
sector
nomination
is
calculated
by
multiplying
the
sum
of
nominations
within
the
sector
by
the
margin
of
error
multiplier.
Page
6
DEFINITIONS
Source
of
yield
loss
estimates
Where
published
studies
of
yield
losses
under
conditions
of
moderate
to
severe
key
pest
pressure
were
not
available
(
the
situation
for
which
the
U.
S.
is
requesting
continued
use
of
MB),
the
U.
S.
developed
such
estimates
by
contacting
university
professors
conducting
experiments
using
MB
alternatives
in
the
appropriate
land
grant
institutions.
The
experts
were
asked
to
develop
such
an
estimate
based
on
their
experience
with
MB
and
with
alternatives.
The
results
of
this
process
were
used
when
better
data
were
not
available.

Source
of
buffer
restriction
implications
for
methyl
bromide
use
Estimates
of
the
impact
of
buffers
required
when
using
some
MB
alternatives
on
the
proportion
of
acreage
where
such
alternatives
could
be
used
were
developed
from
confidential
information
submitted
to
EPA
in
support
of
a
registration
application
for
a
MB
alternative.
Because
at
the
time
of
the
analysis,
a
request
to
reduce
the
size
of
the
required
buffer
for
some
alternatives
was
under
consideration,
a
smaller
buffer
was
selected
for
the
analysis.
Since
that
time
the
size
of
the
regulatory
buffer
has
been
reduced
so
that
it
now
conforms
to
the
Source
of
area
impacted
by
key
pests
estimates
One
of
the
important
determinants
of
the
amount
of
MB
requested
has
been
the
extent
of
area
infested
with
`
key
pests',
that
is,
pests
that
cannot
be
controlled
by
alternatives
to
MB
when
such
pests
are
present
at
moderate
to
severe
levels.
Because
there
are
few
surveys
that
cover
substantial
portions
of
the
areas
for
which
MB
is
requested,
we
have
relied
on
a
variety
of
sources
in
addition
to
the
surveys.
These
sources
include
websites
of
land­
grant
universities;
discussions
with
researchers,
both
those
employed
by
USDA
in
the
Agricultural
Research
Service
(
ARS)
and
those
at
land
grant
universities;
discussions
with
growers
whose
operations
cover
widely
different
locations
encompassing
different
incidences
of
key
pests;
information
from
pesticide
applicators;
and,
information
taken
from
the
applications
themselves.

Source
of
area
impacted
by
regulations
estimates
There
are
two
main
sources
used
to
develop
the
estimate
of
area
impacted
by
regulations.
First,
for
the
impact
of
Township
caps
in
California
we
have
used
a
series
of
papers
by
Carpenter,
Lynch,
and
Trout,
supplemented
by
discussions
with
Dr.
Trout
to
ensure
that
any
recent
regulatory
changes
have
been
properly
accounted
for.
Second,
the
estimate
of
the
area
impacted
by
buffers,
is
described
above.

Source
of
area
impacted
by
soil
type
estimates
First,
for
the
area
impacted
by
karst
topography,
estimates
were
developed
and
mapped
by
he
Florida
Department
of
Environmental
Protection.
The
area
of
California
used
for
agriculture
and
which
is
made
of
clay
soils
unsuitable
for
pest
control
with
a
MB
alternative
has
been
determined
by
discussions
with
agricultural
researchers
and
agricultural
extension
agents
in
California,
and
discussion
with
other
knowledgeable
individuals
such
as
pesticide
applicators.
The
estimates
for
California
understate
the
areas
in
which
alternatives
to
MB
are
not
suitable
because
no
effort
was
made
to
estimate
the
extent
of
hilly
terrain
where
currently
available
substitutes
cannot
be
applied
at
uniform
dosages.
Page
7
Source
of
area
impacted
by
combined
impacts
estimate
Combined
impacts
were
determined
on
a
case­
by­
case
basis
for
each
specific
crop/
location
combination
after
consultation
with
individuals
knowledgeable
with
the
specific
circumstances.
The
nature
of
the
individual
impacts
is
such
that
in
some
situations
they
are
independent
of
each
other,
in
some
they
are
mutually
exclusive,
and
in
some
cover
identical
areas.
It
was
not,
therefore,
possible
to
have
a
formula
that
would
arrive
at
an
appropriate
estimate
of
combined
impacts.
A
more
complete
description
is
found
in
the
footnotes
to
the
`
calculation'
table
REFERENCES
Nesmith,
W.;
2003.
Chemical
options
for
disease
control
in
burley
and
dark
tobacco
transplant
production
systems
 
2003
crop.
Available
at
http://
www.
uky.
edu/
Agriculture/
kpn/
kyblue/
kyblu03/
related/
rtd0301.
htm