UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
February
7,
2005
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
SUBJECT:
BEAD
Review
of
Chlorsulfuron
Comments
FROM:
Nicole
Zinn,
Biologist
Herbicide
and
Insecticide
Branch
Jin
Kim,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

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

TO:
Susan
Jennings,
Chemical
Review
Manager
Special
Review
and
Reregistration
Division
PEER
REVIEW
PANEL:
February
2,
2005
The
purpose
of
this
memorandum
is
to
respond
to
benefits­
related
public
comments
received
regarding
chlorsulfuron's
Phase
3:
Public
Release
of
Risk
Assessments
and
Risk
Management
Options
for
Comment
issued
in
the
Federal
Register
on
September
24,
2004.
Of
seven
comments
received
by
the
Office
of
Pesticide
Programs
(
OPP),
four
had
benefits­
related
comments.
A
benefits
assessment
has
not
been
done
at
this
time.
These
comments
will
be
considered
in
any
benefits
work
conducted
for
chlorsulfuron.
The
following
table
contains
a
summary
of
each
individual
benefits­
related
comment
and
BEAD's
response
to
those
comments.
Only
the
portion
of
the
comments
relevant
to
BEAD
are
included
in
the
table.
2
Table
1.
Summary
of
Chlorsulfuron
Comments
Commenter
Comment
and
BEAD
Response
(
if
any)

Wheat
Jane
Thomas
­
Washington
State
Pest
Management
Resource
Service
Comment:
Chlorsulfuron
is
usually
applied
in
combination
with
metsulfuronmethyl
and
in
conjunction
with
a
phenoxy
herbicide,
on
wheat
on
fields
with
a
wheat/
fallow
rotation.
It
is
applied
in
the
spring
by
air.
Plant
back
restrictions
have
resulted
in
growers
using
either
tribenuron
or
tribenuron
+
thifensulfuron.
Reducing
the
application
rate
or
removing
aerial
application
will
cause
growers
to
switch
to
phenoxy
herbicides
or,
more
likely,
other
sulfonylurea
(
SU)
herbicides.
A
lower
application
rate
may
cause
the
herbicide
to
become
ineffective.
Aerial
application
is
needed
in
the
spring
because
often
the
ground
is
wet.
Delays
in
application
with
ground
equipment
may
result
in
the
herbicide
being
less
effective.

BEAD
Response:
BEAD
believes
that
it
is
possible
that
growers
will
use
a
different
SU
herbicide
if
chlorsulfuron
applications
are
no
longer
feasible
due
to
the
mitigation.
The
concerns
raised
about
reducing
the
application
rate
and
eliminating
aerial
application
are
valid.
However,
BEAD
would
need
to
review
efficacy
data
and
conduct
further
analysis
to
determine
if
the
mitigation
options
are
feasible.
The
information
submitted
in
the
comment
will
be
considered
if
a
benefits
assessment
is
required.

Crop
Not
Specified/
Pasture
and
Rangeland
John
L.
Baker,
Supervisor,
Fremont
County
(
WY)
Weed
and
Pest
Control
District
Comment:
"
Telar
is
the
single
most
effective
herbicide
for
the
control
of
Perennial
Pepperweed
and
Hoary
Cress
in
Wyoming.
The
combination
of
relative
low
cost,
residual,
and
soil
activity
make
it
an
important
part
of
our
weed
control
activities.
While
nearly
all
of
our
application
work
with
Telar
is
with
low
pressure,
large
droplet
hand
directed
sprays,
it
only
seems
prudent
to
preserve
aerial
application
as
an
option
due
to
the
extensive
areas
of
infestation
by
these
weeds
in
rangeland
and
pasture
sites.
Would
it
not
be
possible
to
detail
the
endangered
species
of
concern
and
the
areas
in
which
they
are
found,
than
to
prohibit
aerial
application
all
together?
Drift
control
agents
combined
with
low
drift
equipment
and
technique
may
be
all
that
is
needed
to
reduce
drift
associated
non­
target
impacts."

BEAD
Response:
Chlorsulfuron
is
registered
for
control
of
these
weed
species.
BEAD
has
not
completed
a
benefits
assessment
at
this
time
but
will
consider
this
information
if
a
benefits
assessment
is
required.
Additional
information
on
the
need
for
aerial
application
would
be
necessary
for
this
application
method
to
be
assessed.
Commenter
Comment
and
BEAD
Response
(
if
any)

3
Vegetation
Management
Ferry
County
Noxious
Weed
Control
Board
(
State
not
specified)
Comment:
"
We
have
used
Chlorsulfuron
as
part
of
our
arsenal
of
vegetation
control
herbicides
for
several
years.
We
have
found
it
to
be
a
very
effective
herbicide
for
the
control
of
one
of
our
toughest
noxious
weeds,
Dalmatian
toadflax."

BEAD
Response:
A
number
of
herbicides
are
registered
for
use
on
Dalmatian
toadflax.
North
Dakota
State
University
Extension
Service
lists
picloram,
chlorsulfuron
and
imazapic
as
herbicides
used
to
control
Dalmatian
toadflax
(
ND
Extension,
Web
address:
http://
www.
ext.
nodak.
edu/
extpubs/
plantsci/
weeds/
w1239w.
htm.
Additional
information,
such
as
use
sites
and
comparative
performance
data,
and
an
analysis
of
cost
impacts
would
need
to
be
reviewed
if
a
benefits
assessment
is
required.

Pasture,
Rangeland,
Public
Lands
Leon
J.
Wrage,
South
Dakota
Extension
Agronomist
­
Weeds;
Darrell
L.
Deneke,
South
Dakota
Extension
IPM
Coordinator
Comment:
Chlorsulfuron
is
used
to
control
invasive
weeds
in
pasture,
range
and
public
lands.
Chlorsulfuron
is
not
marketed
on
wheat
in
South
Dakota.
Target
weeds
are
hoary
cress
(
perennial
pepperweed),
Canada
thistle,
biennial
thistle,
common
mullein,
dalmatian
toadflax,
and
tansy.
"
Chlorsulfuron
is
the
most
effective
herbicide
option
for
hoary
cress.
It
is
also
effective
for
perennial
and
biennial
thistle
species.
18%
of
the
infestations
involve
environmental
restrictions
such
as
slope
or
trees
that
preclude
use
of
more
restrictive
products.
There
is
adequate
grass
selectivity
and
tolerance
to
adjacent
deep­
rooted
vegetation
when
used
at
current
rates
and
application
methods."

BEAD
Response:
Chlorsulfuron
is
registered
for
control
of
these
weed
species.
BEAD
has
not
completed
a
benefits
assessment
at
this
time
but
will
consider
this
information
if
a
benefits
assessment
is
required.
