MEMORANDUM
SUBJECT:
Tebuthiuron
Use
Closure
Memo
(PC
Code
105501)

FROM:
Michael
McDavit,
Acting
Chief
Special
Review
Branch
TO:
Margaret
Stasikowski,
Director
Health
Effects
Division
Elizabeth
Leovey,
Acting
Director
Environmental
Fate
and
Effects
Division
This
memo
serves
as
the
Tebuthiuron
Use
Closure
Memo
and
clarifies
Tebuthiuron
uses
for
the
TRED
risk
assessment.

The
SMART
meeting
for
Tebuthiuron
was
held
May
2,
2001.
The
updated
Quantitative
Usage
Analysis
(QUA)
for
Tebuthiuron,
which
is
developed
by
the
Economic
Analysis
Branch
of
the
Biological
and
Economic
Analysis
Division
is
scheduled
for
completion
on
September
9,
2001.
Attached
is
the
most
recent
version
of
the
QUA.

Tebuthiuron
is
a
relatively
nonselective,
soil
activated
herbicide
that
acts
by
inhibiting
photosynthesis.
It
is
used
to
control
broadleaf
and
woody
weeds,
grasses,
and
brush
on
terrestrial
feed
crop
sites
(pastures
and
rangeland)
primarily
in
Texas,
Oklahoma,
and
New
Mexico
and
on
terrestrial
non­
food
crop
sites
including
airports/
landing
fields,
outdoor
industrial
areas,
nonagricultural
rights­
of­
way,
fencerows,
hedgerows,
uncultivated
areas/
soils,
and
under
paved
roads
and
sidewalks
in
areas
where
no
future
landscaping
is
planned.
Primary
uses
include
rangelands
and
near
railroads
and
other
industrial
facilities.
Single
active
ingredient
formulation
include
granular
pelleted/
tableted,
wettable
powder,
water
dispersible
granules
and
technical
grade/
solid
products.
Three
multiple
active
ingredient
formulations
(granulars)
also
are
registered.
All
formulations
may
be
applied
as
broadcast,
banded
or
spot
treatments
using
ground
equipment.
The
pelleted/
tableted
formulation
also
may
be
applied
using
aerial
equipment.
The
LUIS
report
indicates
no
limit
on
the
number
of
applications
per
season
or
crop
cycle,
but,
the
registrant
provided
information
on
the
normal
maximum
and
typical
application
use
rates
of
Tebuthiuron
at
the
SMART
meeting.
The
attached
tables
reflect
the
use
information
(note:
"NS"
not
specified)
reflecting
labeling
current
as
of
02/
21/
2001
in
the
LUIS
report
and
the
registrants'
use
information.

The
risk
assessment
for
Tebuthiuron
will
be
based
on
the
use
sites
listed
in
the
LUIS
report.
Based
on
our
understanding,
this
information
will
allow
EFED
to
submit
it's
draft
TRED
chapter
to
SRRD
on
December
1,
2001,
and
HED
to
submit
it's
draft
TRED
chapter
to
SRRD
on
February
22,
2002,
as
it
is
currently
scheduled.

If
you
have
any
questions
or
concerns
regarding
this
memorandum,
please
contact
Wilhelmena
Livingston
at
(703)
308­
8025.

cc:
Paula
Deschamp
Virginia
Dobozy
Sheila
Piper
Ken
Dockter
Kevin
Costello
Mark
Corbin
Steve
Smearman
Dan
Rosenblatt
Range
and
Pasture
Typical
vs.

Maximum
Use
Rates
Use
Site
and
Product
Name
Application
Method
and
Equipment
Registrant
Maximum
Application
Per
Use
Rate
Reflecting
Label
Maximum
Application
Per
Use
Registrant
Typical
Use
Rate
Reflecting
Label
Typical
Use
Rate
Range
and
Pasture
Oak
Desert
Species
Sand
Shinnery
Spike
20P
(20%

pellet)

Broadcast
and
spot
treatment
Applied
by
hand
using
canister
delivery,
ground
and
aerial
application
For
vulnerable
sites,

maximum
application
rate
is
dependent
upon
annual
precipitation:
°

<20"

in
annual
precipitation:

no
more
than
1
lb
a.
i./

acre
once
every
3
years
°

>20"

in
annual
precipitation:

no
more
than
2
lbs
a.
i./

acre
once
every
3
years
For
non­

vulnerable
sites,

maximum
application
rate
is
dependent
upon
annual
precipitation:
°

<20"

in
annual
precipitation
no
more
than
2
lbs
once
every
3
years
and
no
more
than
two
treatments
totaling
6
lbs
a.
i./

acre
in
any
6­

year
period
°

>20"

in
annual
precipitation:

on
more
than
4
lbs
a.
i./

acre
once
every
3
years
and
no
more
than
two
treatments
totaling
6
lbs
a.
i./

acre
in
any
6­

year
period
4
lbs
a.
i./

acre/
NS
for
broadcast
treatment
4
lbs
a.
i./

acre/
yr
for
spot
treatment
Typical
application
is
once
every
10­
20
years
1.0­
1.4
lbs
for
oak
use
1.5
lbs
for
desert
species
0.3­
0.5
lbs
for
sand
shinnery
NS
Industrial
Vegetation
Management
Typical
vs.

Maximum
Use
Rates
Use
Site
and
Product
Name
Application
Method
and
Equipment
Registrant
Maximum
Application
Per
Use
Rate
Reflecting
Label
Maximum
Application
Per
Use
Registrant
Typical
Use
Rate
Reflectin
g
Label
Typical
Use
Rate
Industrial
Vegetation
Management
Non­
Cropland
Railroad
Industrial
General
Woody
Plant
Spike
80DF
(80%
dry
flowable)
Broadcast/
Ban
ded
and
spot
Applied
by
backpack
sprayer,
handgun
sprayer,
and
groundboom
sprayer
For
vulnerable
sites,
maximum
application
rate
is
dependent
upon
annual
precipitation:

°
<20"
in
annual
precipitation
for
broadcast/
banded
and
spot
application:
no
more
than
1
lb
a.
i./
acreonce
every
3
years
°>
20"
in
annual
precipitation
for
broadcast/
banded
and
spot
application
no
more
than
2
lb
a.
i./
acreonce
every
3
years
For
non­
vulnerable
sites,
maximum
application
rate
is
dependent
upon
annual
°
<20"
and
>20"
in
annual
precipitation
for
broadcast/
banded
application
for
vegetation
control:
no
more
than
4
lbs
a.
i./
acre
once
every
3
years
and
no
more
than
two
treatments
totaling
6
lbs.
a.
i./
acre
in
any
6­
year
period;
for
total
vegetation
control
and
maintenance
of
bare
ground
(ground
broadcast
only)
applied
only
once
per
year,
however
no
more
than
6
lbs
a.
i./
acre
may
be
applied
in
any
3­
year
period.

°
<20"
and
>20"
in
annual
precipitation
for
spot
application
no
more
than
6
lb
a.
i./
acre
once
every
three
years
Maximum
application
rate
is
6­
8
lbs/
acre,
depending
on
the
use
site
Typically
applied
to
railroad
and
industrial
annually
for
2­
3
years
followed
by
rotation
to
other
products
Typically
applied
to
general
woody
plant
once
every
3
8
years
1.6­
2.4
lbs
for
railroad
use
1.6­
2.4
lbs
for
industrial
use
3­
4
lbs
for
general
woody
plant
use
NS
