UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
July
13,
2001
MEMORANDUM
SUBJECT:
BEAD's
Review
of
Documentation
Submitted
in
Support
of
an
Emergency
Exemption
for
the
Use
of
Imidacloprid
on
Stone
Fruits
(
Commercial
and
Residential),
Almonds,
and
Blueberries
to
Control
the
Glassy­
winged
Sharpshooter
(
01­
CA­
0022,
01­
CA­
0023,
01­
CA­
0024,
01­
CA­
0029)
(
D275309,
and
D275528).

FROM:
David
W.
Brassard,
Senior
Entomologist
Herbicide
and
Insecticide
Branch
Anthony
Gilbert,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THRU:
Jonathan
Becker,
Acting
Chief
Herbicide
and
Insecticide
Branch
David
Widawsky,
Acting
Chief
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

TO:
Andrew
Ertman/
Meredith
Laws/
Rob
Forrest
Minor
Use,
Inerts
&
Emergency
Response
Branch
Registration
Division
(
7505C)

Reviewed
by
Peer
Review
Committee:
July
11,
2001
SUMMARY
The
California
Department
of
Pesticide
Regulation
(
CDPR)
is
requesting
the
use
of
imidacloprid
on
8,000
acres
of
commercial
stone
fruits
and
1,000
acres
of
residential
stone
fruits,
89,000
acres
of
almonds,
and
100
acres
of
blueberries
as
part
of
an
an
area­
wide
management
program
to
control
the
glassy­
winged
sharpshooter
(
GWSS).

The
situation
is
considered
non­
routine
because
of
the
recent
introduction
of
the
glassywinged
sharpshooter.
The
GWSS
is
a
serious
new
threat
to
California
vineyards
because
it
vectors
Pierce's
disease,
a
bacterial
disease
that
can
kill
infected
vines
within
12
months.
GWSS
has
also
demonstrated
the
ability
to
vector
almond
leaf
scorch,
another
potentially
lethal
disease.
GWSS
populations
often
build
up
in
stone
fruit
and
almond
orchards
and
in
blueberry
fields
and
move
on
to
grapes.
Currently
registered
alternatives
do
not
provide
extended
control
of
GWSS
and/
or
are
not
compatible
with
current
IPM
systems.
Without
imidacloprid,
many
grape
growers
will
experience
significant
economic
losses.

THE
INTRODUCTION
OF
THE
GLASSY­
WINGED
SHARP­
SHOOTER
(
GWSS)
INTO
CALIFORNIA
MAKES
THIS
AN
URGENT
NON­
ROUTINE
SITUATION.

The
glassy­
winged
sharpshooter
(
GWSS),
Homalodisca
coagulata,
is
a
new
pest
that
has
recently
become
established
in
stone
fruit
and
almond
orchards
and
in
blueberry
fields
and
grape
vineyards.
Although
the
GWSS
can
cause
cosmetic
damage
to
stone
fruits
and
blueberry,
it
is
not
considered
a
serious
threat
to
these
crops.
The
glassy­
winged
sharpshooter
(
GWSS)
is
a
serious
new
threat
to
California
grape
vineyards
because
it
vectors
Pierce's
disease,
a
strain
of
the
bacteria
Xylella
fastidiosa.
Pierce's
disease
is
a
serious
disease
that
can
kill
infected
vines
within
12
months.
The
GWSS
has
already
spread
Pierce's
disease
throughout
vineyards
in
the
Temucula
region
of
Southern
California.
In
addition
to
causing
Pierce's
disease,
strains
of
the
bacteria
cause
such
problems
as
almond
leaf
scorch,
alfalfa
dwarf,
oleander
leaf
scorch
and
citrus
variegated
chlorosis.
Almond
leaf
scorch
was
found
in
large
amounts
in
the
Lancaster
area
of
Kern
County
California
in
1979
and
1980
and
the
epidemic
was
so
severe
and
widespread
that
whole
orchards
were
wiped
out.
In
Brazil,
it
causes
citrus
variegated
chlorosis,
which
has
killed
as
many
as
80,000
citrus
trees.

Before
GWSS
arrived,
the
Blue
Green
sharpshooter
(
BGSS)
was
the
most
important
vector
of
Pierce's
disease
in
California.
Several
factors
make
the
GWSS
a
more
important
vector
than
the
BGSS.
First
the
GWSS
moves
faster
and
further
into
vineyards
and
feeds
and
reproduces
on
a
wider
range
of
plants
than
the
BGSS.
Second,
because
the
GWSS
feeds
much
lower
on
the
cane
than
other
sharpshooters
in
California,
late
season
(
after
May­
June)
infections
introduced
by
the
glassy­
winged
sharpshooter
may
survive
the
winter
to
cause
chronic
Pierce's
disease.
This
would
enable
vine­
to­
vine
spread
of
Pierce's
disease,
which
has
not
yet
been
the
case
in
California.
If
this
occurs,
vine­
to­
vine
spread
can
be
expected
to
increase
the
incidence
of
Pierce's
disease
exponentially
rather
than
linearly
over
time,
as
has
been
normal
for
California
vineyards
affected
by
Pierce's
disease.
The
BGSS,
on
the
other
hand
feeds
mainly
on
leaves
which
usually
does
not
result
in
systemic
infections
of
Pierce's
disease.

CURRENTLY
REGISTERED
ALTERNATIVES
DO
NOT
PROVIDE
EXTENDED
CONTROL
OF
GWSS
AND
ARE
NOT
COMPATIBLE
WITH
CURRENT
IPM
SYSTEMS.

Because
GWSS
populations
build
up
in
stone
fruit
and
almond
orchards
and
in
blueberry
fields
and
then
move
to
grapes,
an
important
strategy
is
to
control
GWSS
on
these
crops
before
populations
emigrate
to
grape
vineyards.
To
this
end,
California
has
adopted
an
area­
wide
management
program
to
control
the
GWSS.
Stone
fruit,
almond
and
blueberry
growers
want
imidacloprid
because
it
is
effective,
less
disruptive
to
beneficial
arthropods,
and
has
a
longer
period
of
residual
activity
than
currently
registered
insecticides
(
e.
g.
chlorpyrifos).
Additionally,
they
are
concerned
about
the
use
of
multiple
applications
of
broad
spectrum
organophosphate
insecticides
has
the
potential
to
negatively
impact
beneficial
organisms
and
to
upset
their
IPM
programs.

WITHOUT
IMIDACLOPRID,
MANY
GRAPE
GROWERS
WILL
EXPERIENCE
SIGNIFICANT
ECONOMIC
LOSSES
In
order
to
estimate
the
economic
impact
and
minimum
yield
loss
that
would
generate
a
significant
economic
loss,
the
net
revenue
method
is
applied
using
a
historical
range
of
a
price
and
yield
data.
Minimum
yield
loss
is
defined
as
the
economic
loss
that
reduces
net
revenue
of
California
stone
fruit,
almond
and
blueberry
growers
from
the
average
value
to
their
five
year
minimum
value
with
price
and
cost
held
constant.
In
this
case,
however,
the
principal
crop
at
risk
are
grapes.
The
GWSS
is
a
vector
for
Pierce's
disease,
which
can
kill
infected
vines
within
12
months.
Given
the
lethal
efficiency
of
this
disease
and
no
reliable
means
of
control,
the
potential
risk
to
the
$
2.8
billion
dollar
grape
industry
could
be
substantial.
A
widespread
epidemic
of
Pierce's
disease
could
devastate
the
major
grape
growing
regions
of
California,
leading
to
losses
of
up
to
100%.
Based
on
the
yield
loss
estimates
of
this
magnitude,
significant
economic
losses
are
probable.
