UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

	OFFICE OF PREVENTION, PESTICIDE

	AND TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:  08/20/09

SUBJECT:	Azoxystrobin.  Section 3 Amendment to Reduce the Preharvest
Interval for Barley Grain and Straw and to Add Seed Treatment Uses on
Head and Stem Brassica Vegetables (Subgroup 5A) and Sorghum, Grain. 
Summary of Analytical Chemistry and Residue Data.

PC Code:  128810	DP Barcodes:  362963 & 363046

Decision Nos.:  401489 & 403237	Registration Nos.:  100-1098 & 100-1159

Petition No.:  PP#8E7474	Regulatory Action:  Amended Section 3

Risk Assessment Type:  Single Chemical/Aggregate	Case No.:  NA

TXR No.:  NA	CAS No.:  131860-33-8

MRID No.:  47486501	40 CFR:  180.507

	Ver.Apr.08

FROM:	Meheret Negussie, Chemist

Risk Assessment Branch III

Health Effects Division (7509P)

  SEQ CHAPTER \h \r 1 

THROUGH:	Leung Cheng, Senior Chemist

Risk Assessment Branch III

Health Effects Division (7509P)

			

TO:		Tony Kish, RM# 22/Barbara Madden, RM#05

		Fungicide Branch		  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 

		Registration Division (7505P)		  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h
\r 1 

	

  SEQ CHAPTER \h \r 1 This document was originally prepared under
contract by Dynamac Corporation (1901 Research Boulevard, Suite 220;
Rockville, MD 20850). The document has been reviewed by the Health
Effects Division (HED) and revised to reflect current Office of
Pesticide Programs (OPP) policies.

 

Executive Summary

Azoxystrobin is a broad-spectrum fungicide and belongs to a class of
pesticidal compounds called β-methoxyacrylates, which are derived from
the naturally occurring strobilurins (Group 11 fungicide).  The
biochemical mode of action is inhibition of electron transport.  The
fungicide is currently registered for use on a variety of field,
vegetable, fruit, and nut crops as well as on ornamental plants and
turf.  End-use products of azoxystrobin are typically formulated as
water dispersible granular (WDG) and suspension concentrate (SC;
previously referenced as flowable concentrate) formulations.  These
products may be applied as in-furrow at planting or postemergence foliar
applications using ground or aerial equipment at maximum seasonal rates
of 0.40-2.0 lb ai/A.  Azoxystrobin is also registered for seed treatment
of many food/feed crops as well as for postharvest uses on
bananas/plantains and citrus fruits.

Under PP#8E7474, Interregional Research Project No. 4 (IR-4), on behalf
of the Agricultural Experiment Stations of CO, ID, ND, and SD, is
requesting revision of the established tolerances for the combined
residues of the fungicide azoxystrobin,
[methyl(E)-2-(2-(6-(2-cyanophenoxy)pyrimidin-4-yloxy)phenyl)-3-methoxyac
rylate] and the Z-isomer of azoxystrobin,
[methyl(Z)-2-(2-(6-(2-cyanophenoxy)pyrimidin-4-yloxy)phenyl)-3-methoxyac
rylate], expressed as parent compound, in or on barley raw agricultural
commodities as follows:

Barley, grain	3.0 ppm

Barley, straw	7 ppm

Concurrently, IR-4 wishes to amend the product label for Abound®
Flowable Fungicide (EPA Reg. No. 100-1098), a SC formulation containing
22.9% ai (2.08 lb ai/gal) azoxystrobin, to modify the registered foliar
uses on barley to reduce the preharvest interval (PHI) for grain and
straw from 45 days to 14 days in Arizona, Colorado, Idaho, western
Montana, Nevada, New Mexico, Oregon, west Texas, Utah, Washington, and
western Wyoming.  

Separately, Syngenta Crop Protection, Inc. has requested to amend the
label for Dynasty® Fungicide (EPA Reg. No. 100-1159), a SC formulation
containing 9.6% ai (0.83 lb ai/gal) azoxystrobin, to add seed treatment
uses on sorghum, grain and the head and stem Brassica subgroup 5A.  The
proposed seed treatment rates correspond to field equivalent rates of
0.0012-0.002 lb ai/A.

  SEQ CHAPTER \h \r 1 Azoxystrobin tolerances have been established in
40 CFR §180.507.  Tolerances for crop commodities are listed in 40 CFR
§180.507(a)(1) and are expressed in terms of residues of the fungicide
azoxystrobin and the Z-isomer of azoxystrobin.  Tolerances are currently
established for barley bran (0.2 ppm), forage (25 ppm), grain (0.1 ppm),
hay (15 ppm), and straw (4 ppm); sorghum, grain, forage (25 ppm), grain
(11 ppm), and stover (40 ppm); and head and stem Brassica subgroup 5A
(3.0 ppm).  Tolerances for livestock commodities are listed in 40 CFR
§180.507(a)(2) and are expressed in terms of residues of azoxystrobin. 
The established tolerances for livestock commodities range from 0.006
ppm for milk to 0.07 ppm for the meat byproducts of cattle, goat, horse,
and sheep; no tolerances are currently established for poultry
commodities.

The nature of the residue in plants, rotational crops, and animals is
adequately understood.  Acceptable metabolism studies have been
conducted on primary crops of grapes, peanuts, and wheat as well as on
representative rotational crops.  Acceptable metabolism studies on goats
and laying hens are also available.  The residues of concern in/on
primary and rotational crop commodities, for tolerance expression and
risk assessment purposes, are azoxystrobin and its Z-isomer.  The
residue of concern in livestock is parent azoxystrobin only.

Adequate residue analytical methods are available for tolerance
enforcement:  a gas chromatography method with nitrogen-phosphorus
detection (GC/NPD), RAM 243/04, for the analysis of crop commodities for
residues of azoxystrobin and its Z-isomer; and a GC/NPD method, RAM
255/01, for analysis of livestock commodities for residues of
azoxystrobin.  

For analysis of samples from the barley field trials associated with the
current petition, a high performance liquid chromatography (LC) method
with tandem mass spectroscopy detection (MS/MS), Method 305/03, was used
as the data-collection method.  RAM 305/03 was adequately validated at
fortification levels ranging from 0.01-1.0 ppm for barley grain and
0.01-5.0 ppm for barley straw.  

Adequate cattle and poultry feeding studies are available to support the
proposed uses.  No changes to the existing livestock commodity
tolerances are needed.  

Acceptable barley crop field trial studies have been submitted to
support the requested regional change in the PHI for barley grain and
straw; the studies are supported by adequate storage stability data. 
The field trial data will support the proposed tolerances of 3.0 ppm for
barley, grain and 7.0 ppm for barley, straw.  

The petitioner requested to register seed treatment use of the SC
formulation of azoxystrobin on sorghum, grain and head and stem Brassica
vegetables.  Adequate field trial data are available for foliar
applications, reflecting applications to head and stem Brassica
vegetables at a total seasonal rate of 1.50 lb ai/A, with a 0-day PHI,
and applications to sorghum, grain, forage at a total seasonal rate of
0.50 lb ai/A, and 0.75 lb ai/A for sorghum, grain, grain and stover,
with 14-day PHIs.  The proposed seed treatment uses are not expected to
increase residue levels in treated head and stem Brassica and sorghum,
grain matrices; therefore, no changes are needed to the established
tolerances for the commodities of head and stem Brassica subgroup 5A and
sorghum, grain.

The proposed reduced PHI for barley grain results in higher residues in
the grain, and therefore the potential for increased residues in barley
bran.  The available data support an increased tolerance of 6.0 ppm for
barley, bran.  

Adequate field rotational crop data are available to support the
existing rotational crop restrictions on the product labels; a 12-month
plantback interval has been established for buckwheat, millet, oats, and
rye; and a 36-day plantback interval has been established for leafy
vegetables (except Brassica) group, Brassica leafy greens subgroup, root
vegetables subgroup, tuberous and corm vegetable subgroup, and leaves of
root and tuber vegetables group.

Codex maximum residue limits (MRLs) have been established for
azoxystrobin in barley, grain (0.5 ppm) and straw and fodder (dry) of
cereal grains (except maize) at (15 ppm).  There are no Canadian MRLs
for residues of azoxystrobin and its (Z)-isomer for the requested crops.
 Mexican MRLS have been established for residues of ‘azoxistrobin’;
MRLs have been established for barley, grain (0.3 ppm). 

The Codex MRLs for barley grain and straw are based on trials conducted
in Europe and on residues present at a 35-42 day PHI.  The recommended
US tolerances on barley grain (3.0 ppm) and straw (7.0 ppm) are based on
residues present at a 14-day PHI.  The US MRL for grain is higher due to
shorter PHI.  The Codex MRL for straw is for cereal grains straw and
encompasses barley, corn, sweet corn, oats, rice, and wheat data from
Europe.  Moreover, Codex MRLs for forages, straws, and the like are set
on a dry-weight basis, whereas US tolerances are set on an as-fed basis.

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

HED has examined the residue chemistry database for azoxystrobin. 
Pending submission of a revised Section B (see requirements under
Directions for Use) and a revised Section F (see requirements under
Proposed Tolerances), there are no residue chemistry issues that would
preclude granting Section 3 registration for the requested seed
treatment uses of azoxystrobin on head and stem Brassica vegetables
(subgroup 5A) and sorghum, grain, the requested regionally restricted
reduced PHI for barley grain and straw, or revision of the established
tolerances for residues of azoxystrobin, as follows:

Barley, bran	6.0 ppm

Barley, grain	3.0 ppm

Barley, straw	7.0 ppm

A human health risk assessment is forthcoming.

Note to PM:  Because the requested regional reduction in PHI results in
the need for greatly increased tolerances for barley bran, grain, and
straw, the Office of General Counsel should be consulted to determine
whether separate tolerances with regional registration should be
established under 40 CFR §180.507(c) for barley bran, grain, and straw
(at the levels above), or the existing national tolerances for barley
bran, grain, and straw [under 40 CFR §180.507(a)(1)] should be
increased (ChemSAC 05/27/09).

860.1200 Directions for Use

The proposed supplemental label for EPA Reg. No. 100-1098 for use on
barley requires several modifications to clarify the proposed uses:

The label should state that the use directions only apply to barley
grain and straw grown in the following areas/states:   Arizona (north of
I-10), Colorado, Idaho, western Montana (west of Route 87 and I-15),
Nevada, New Mexico, Oregon, western Texas (west of Route 283 and
northwest of Route 377), Utah, Washington, and western Wyoming (west of
I-25 and south of I-90).  

The statement that application to barley should be made no later than
Feekes growth stage 10.5 (Zadok’s growth stage 59) should be removed
from the label.  

A 14-day minimum retreatment interval should be proposed.  

The label must state that no adjuvants may be added to the spray mixture
for this type of application to barley.

Note to PM: The label (EPA Reg. No. 100-1098) states that Azoxystrobin
is registered for use on all other rotated crops and all other crops may
be planted immediately after the last treatment.  The label should be
revised to state “Crops with registered uses may be planted
immediately after the last treatment unless otherwise specified.  For
crops not on the label, a 12-month PBI must be observed unless otherwise
specified”. 

860.1550 Proposed Tolerances

IR-4 must propose an increased tolerance for residues of azoxystrobin
and its Z-isomer in barley bran at 6.0 ppm.  

Background

The chemical structure and nomenclature of azoxystrobin and its
Z-isomer, and the physicochemical properties of the technical grade of
azoxystrobin are presented in Tables 1 and 2, respectively.

Table 1.	Azoxystrobin Nomenclature.

Compound	

Common name	Azoxystrobin

Company experimental name	ICIA5504 (Zeneca), R215504 (Syngenta)

IUPAC name	methyl
(E)-2-{2-[6-(2-cyanophenoxy)pyramidin-4-yloxy]phenyl}-3-methoxyacrylate

CAS name
methyl-(E)-2-[[6-(2-cyanophenoxy)-4-pyrimidinyl]oxy]-(methoxymethylene)-
benzeneacetate

CAS registry number	131860-33-8

End-use products (EP)	Abound® Flowable Fungicide (EPA Reg. No.
100-1098)

Dynasty® Fungicide (EPA Reg. No. 100-1159)

Regulated metabolite, Z-isomer	

Common name	Azoxystrobin, Z-isomer

Chemical name	methyl
(Z)-2-{2-[6-(2-cyanophenoxy)pyramidin-4-yloxy]phenyl}-3-methoxyacrylate



Table 2.	Physicochemical Properties of Technical Grade Azoxystrobin.

Parameter	Value	Reference

Melting point/range	114-116ºC	DP#s 218318 and 218448, 3/19/96, J.
Garbus

pH	6.4

	Density	1.25 g/cm3

	Water solubility (20°C)	pH 5.2	6.7 mg/L

pH 7.0	6.7 mg/L

pH 9.2	5.9 mg/L

	Solvent solubility (20°C)	Hexane	0.057 mg/L

Octanol	1.4 mg/L

Methanol	20 mg/L

Toluene	55 mg/L

Acetone	86 mg/L

Ethyl Acetate	130 mg/L

Acetonitrile	340 mg/L

Dichloromethane	400 mg/L

	Vapor pressure (20°C)	1.1x10-13 kPa (8.2x10-13 mm Hg)

	Dissociation constant, pKa	Not dissociable

	Octanol/water partition coefficient, Log(KOW)	log POW = 2.5

	UV/visible absorption spectrum	Not available

	

860.1200 Directions for Use

A summary of the azoxystrobin end-use products proposed for use on the
crops discussed in this document is listed in Table 3.  IR-4 has
proposed to amend the use pattern of the 2.08 lb ai/gal SC formulation
(EPA Reg. No. 100-1098) on barley to reduce the PHI for barley grain and
straw in certain areas of the western U.S. from 45 days to 14 days.  To
support this proposal, IR-4 included in Section B of the petition both a
text description of the proposed use as well as a proposed supplemental
label.  A summary of the uses on the proposed supplemental label are
presented in Table 4.

In addition, Syngenta has proposed to amend the label for the 0.83 lb
ai/gal SC formulation (EPA Reg. No. 100-1159) to add seed treatment use
on sorghum, grain and the head and stem Brassica vegetables subgroup and
submitted a copy of a proposed label (dated 10/15/08).  The proposed
uses are summarized in Table 4.

Table 3.	Summary of Proposed Azoxystrobin End-Use Products.

Trade Name	Reg. No.	% ai of formulation	Formulation Type	Target Crop
Label Date

Abound® Flowable Fungicide	100-1098	22.9% ai 

(2.08 lb ai/gal) 	SC	Barley	Proposed supplemental label dated 7/10/08;

undated text use directions

Dynasty® Fungicide	100-1159	9.6% ai 

(0.83 lb ai/gal)	SC	Head and stem Brassica vegetables and sorghum, grain
Proposed label dated 10/15/08



Table 4.	Summary of Directions for Use of Azoxystrobin.

Applic. Timing, Type, and Equip. 	Formulation

[EPA Reg. No.]	Applic. Rate 

(lb ai/A)	Max. No. Applic. per Season	Max. Seasonal Applic. Rate

(lb ai/A)	PHI

(days)	Use Directions and Limitations

Barley

Foliar

Ground, aerial or chemigation	2.08 lb ai/gal SC

[100-1098]	0.10-0.20	2	0.40	14 	Applications are to be made prior to
disease development up to late head emergence (Feekes 10.5 or Zadok’s
59, BBCH-59) stage.  A crop oil concentrate adjuvant may be added at
1.0% v/v.  The 14-day PHI for grain and straw is specified for AZ, CO,
ID, MT, NV, NM, OR, west TX, UT, WA, and WY only.  

Head and Stem Brassica Subgroup 5A (broccoli, Brussels sprouts, cabbage,
cauliflower, Cavolo broccolo, Chinese broccoli, Chinese cabbage (napa),
Chinese mustard cabbage, kohlrabi)

Seed treatment	0.83 lb ai/gal SC

[100-1159]	0.001-0.024

lb ai/100 lb seed

(0.0012 lb ai/A)1	Not specified	Apply as a water-based slurry using seed
treatment application equipment; use with an EPA-approved dye.  The use
of treated seed for food, feed, or oil purposes is prohibited.

Sorghum, Grain

Seed treatment	0.83 lb ai/gal SC

[100-1159]	0.010-0.020

lb ai/100 lb seed

(0.0020 lb ai/A)2	Not specified	Apply as a water-based slurry using seed
treatment application equipment; use with an EPA-approved dye.  The use
of treated seed for food, feed, or oil purposes is prohibited.

1  Calculated using the maximum head and stem Brassica seeding rate of 5
lb/A, specified for kohlrabi in HED EXPOSAC SOP 15 (“Amount of Seed
Treated or Planted Per Day,” 3/2/04).

2  Calculated using the maximum seeding rate for sorghum, grain of 10
lb/A (HED EXPOSAC SOP 15). 

The proposed supplemental label for the 2.08 lb ai/gal SC formulation
specifies that all applicable directions, restrictions, and precautions
on the EPA-registered label are to be followed.  The most recent label
for Abound® Flowable Fungicide (EPA Reg. No. 100-1098, main label dated
7/27/07 and supplemental label accepted 7/10/08) specifies that the
product should be integrated into an overall disease and pest management
strategy and that for resistance management, no more than two foliar
applications of Abound® Flowable Fungicide or other Group 11 fungicides
should be made before alternating with a fungicide having a different
mode of action (not in Group 11).  The following plantback intervals
(PBIs) have been established:  12 months for buckwheat, millet, oats,
and rye; 36 days for leafy vegetables (except Brassica) group, Brassica
leafy greens subgroup, root vegetables subgroup, tuberous and corm
vegetable subgroup, and leaves of root and tuber vegetables group; and 0
days for all other crops.  

The text description of the proposed uses on barley specifies a minimum
retreatment interval of 14 days; no retreatment intervals are specified
on the supplemental label.  The text use directions also specify that
the proposed use is to be restricted to “Western Montana (W. of Rt. 87
/ I-15), Western Wyoming (W. of I-25 / I-90), Colorado, West Texas (W.
of Rt. 283 / 377), New Mexico, Arizona (N. of I-10), Utah, Nevada,
Idaho, Oregon and Washington.”

The 2.08 lb ai/gal SC formulation is currently registered for use on
barley at a maximum seasonal rate of 0.40 lb ai/A, with a 14-day PHI for
forage and hay and 45-day PHI for grain and straw (supplemental label
accepted 7/10/2008).  

The 2.08 lb ai/gal SC formulation is also registered for foliar
applications to head and stem Brassica vegetables at a maximum seasonal
rate of 1.50 lb ai/A with a 0-day PHI (label dated 7/27/07).  In
addition, the 2.08 lb ai/gal SC formulation is registered for foliar
applications to sorghum, grain, forage at maximum seasonal rates of 0.50
lb ai/A, and 0.75 lb ai/A for sorghum, grain, grain and stover; a 14-day
PHI has been established for sorghum, grain, forage, grain, and stover
(supplemental label accepted 7/10/2008). 

Conclusions:  The label directions are adequate to allow evaluation of
the residue data relative to the proposed use.  The proposed
supplemental label for seed treatment use on head and stem Brassica
vegetables and sorghum, grain is adequate; no amendments are required.  

The petitioner included both a text description of the proposed use on
barley and a supplemental label for EPA Reg. No. 100-1098 dated 7/14/08,
with use directions on barley.  The text use directions generally
reflect the use pattern of the crop field trials.  However, the
supplemental label for barley requires several modifications to clarify
the proposed uses.  The label should state that the use directions only
apply to barley grain and straw grown in the following areas/states:  
Arizona (north of I-10), Colorado, Idaho, western Montana (west of Route
87 and I-15), Nevada, New Mexico, Oregon, western Texas (west of Route
283 and northwest of Route 377), Utah, Washington, and western Wyoming
(west of I-25 and south of I-90).  The statement that application to
barley should be made no later than Feekes growth stage 10.5 (Zadok’s
growth stage 59) should be removed from the label.  A 14-day minimum
retreatment interval should be proposed.  

The submitted crop field trial data did not reflect the use of any spray
adjuvants in the application mixtures.  Therefore, the supplemental
label must state that no adjuvants may be added to the spray mixture for
this type of application to barley.

860.1300 Nature of the Residue - Plants

PP#5F4541; DP#s 218318 and 218448, 3/19/96, J. Garbus 

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney 

HED Metabolism Assessment Review Committee Decision Memo; DP# 251683,
12/30/98, W. Wassell

Adequate metabolism studies on grapes, peanuts, and wheat were submitted
in conjunction with earlier azoxystrobin petitions, PP#s 5F4541 and
6F4762.  Azoxystrobin undergoes photochemical isomerization to produce
the Z-isomer and is extensively metabolized in plants.  The parent
compound undergoes cleavage of the ether linkages between the
phenylacrylate and pyrimidinyl rings and the cyanophenyl and pyrimidinyl
rings, with subsequent oxidation, hydrolysis, and/or reduction of the
primary metabolites to form numerous secondary metabolites. 
Azoxystrobin is systemic.  HED has determined that the residues of
concern in/on plants for tolerance expression and risk assessment
purposes are azoxystrobin and its Z-isomer.

860.1300 Nature of the Residue - Livestock

PP#5F4541; DP#s 218318 and 218448, 3/19/96, J. Garbus 

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney 

HED Metabolism Assessment Review Committee Decision Memo; DP# 251683,
12/30/98, W. Wassell

The nature of the residue in livestock is adequately understood based on
acceptable metabolism studies conducted on goats and laying hens.  HED
has determined that the residue of concern in livestock is parent
azoxystrobin only. 

860.1340 Residue Analytical Methods

Enforcement methods

PP#s 5F4541 & 6F4762; DP# 235342, 5/30/97, C. Stafford

PP#7F4864; DP#s 249657 and 249668, 1/25/99, D. Dotson 

PP#s 6F7106 & 7F7198; DP#s 334571 & 340016, 3/12/08, W. Cutchin

Crop commodities:  A GC/NPD method, RAM 243/04, is available for the
enforcement of tolerances for residues of azoxystrobin and its Z-isomer
in crop commodities.  The method has undergone method validation by
ACB/BEAD.  The method was revised to incorporate comments made by BEAD,
and the revised method (designated RAM 243, dated 5/15/98) has been
submitted to FDA for inclusion in Pesticide Analytical Manual (PAM),
Volume II.  The limit of quantitation (LOQ) is 0.01 ppm for each analyte
in crop commodities.  

Livestock commodities:  A GC/NPD method, RAM 255/01, is available for
the enforcement of tolerances for residues of azoxystrobin in livestock
commodities.  The method has been validated by ACB/BEAD for the analysis
of milk and liver.  The method LOQ is 0.0025 ppm and 0.01 ppm for each
analyte in milk and tissues, respectively.

Data-collection method

Samples from the barley field trials submitted with the current petition
were analyzed for residues of azoxystrobin and its Z-isomer using
LC/MS/MS Method 305/03.  This method has been reviewed previously by
HED, under PP#s 6F7106 and 7F7198.  

Briefly, samples were extracted with acetonitrile (ACN):water (90:10,
v:v) and the extract was isolated by filtration and brought to volume
using ACN.  An aliquot of the extract was cleaned up on a C18 solid
phase extraction column using ethyl acetate:dichloromethane (55:45, v:v)
to elute residues.  The eluate was evaporated to dryness and redissolved
in ACN:water (1:1, v:v) for LC/MS/MS analysis.  The lower limit of
method validation (LLMV) for barley grain and straw was 0.01 ppm for
each analyte.

The method was adequately validated concurrently with the analysis of
field samples; samples of barley grain and straw were fortified with
azoxystrobin and its Z-isomer each at 0.01-1.0 ppm (grain) or 0.01-5.0
ppm (straw).  The fortification levels adequately bracketed expected
residue levels. 

Conclusions:   There are adequate residue analytical methods for
tolerance enforcement in crop and livestock commodities.  The LC/MS/MS
method used for determination of azoxystrobin and its Z-isomer in barley
grain and straw, RAM 305/03, was adequate for data collection purposes
based on acceptable concurrent method recoveries. 

860.1360 Multiresidue Methods

PP#5F4541; DP#s 218318 and 218448, 3/19/96, J. Garbus 

Data have previously been submitted pertaining to the multiresidue
methods testing of azoxystrobin in conjunction with the grape petition
(PP#5F4541).  The data indicate that azoxystrobin could not be recovered
through application of the multiresidue protocols.  These data have been
forwarded to FDA for inclusion in PAM I.

860.1380 Storage Stability

PP#7F4864; DP#s 248887 and 249671, 10/14/98, D. Dotson, et al.

PP#7F4864; DP#s 249657 and 249668, 1/25/99, D. Dotson

Adequate storage stability data are available indicating that
azoxystrobin and its Z-isomer are reasonably stable under frozen
conditions in/on fortified samples of diverse crops.  In previous
studies, residues were determined to be stable for two years in/on
apple, banana, carrot, cucumber, grape, leaf lettuce, rape seed, peach,
winter wheat straw, wheat forage, and wine.  Over the two-year period,
residues of both azoxystrobin and its Z-isomer decreased by up to 20% in
winter wheat grain and by up to 27% (azoxystrobin only) in tomato,
peanut, and pecan, but all recoveries were >70%; residues in these crops
were stable (without decrease) for up to 6-8 months of storage.

Previous studies conducted on processed commodities demonstrated that
fortified residues of azoxystrobin and its Z-isomer were generally
stable under frozen conditions in peanut oil and meal, tomato juice and
paste, and wheat bran for up to one year, and in soybean meal, corn
grits, and orange oil, juice and pulp for at least two years.

Samples of barley grain and straw from the submitted barley field trial
study were stored frozen from harvest to analysis for up to 366 days (12
months).  The available wheat grain and straw storage stability data may
be translated to barley grain and straw.  

Conclusions:  There are adequate storage stability data from previous
submissions to validate the storage conditions and durations of samples
from the submitted barley field trials.  Residues of azoxystrobin and
its Z-isomer were found to be relatively stable over a wide range of
commodities under frozen storage conditions for up to 2 years.  Since
recoveries in wheat grain were still >70% after 24 months storage, and
residues did not decline until after 6-8 months, there is minimal
concern of residue decline in samples stored for 12 months (maximum
storage duration for barley grain samples).

860.1400 Water, Fish, and Irrigated Crops

There are no proposed uses relevant to this guideline topic.

860.1460 Food Handling

There are no proposed uses relevant to this guideline topic.

860.1480 Meat, Milk, Poultry, and Eggs

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney 

PP#7F4864; DP#s 249657 and 249668, 1/25/99, D. Dotson 

Tolerances for residues of azoxystrobin are currently established [40
CFR §180.507(a)(2)] for the fat (0.03 ppm), meat (0.01 ppm), and meat
byproducts (0.07 ppm) of cattle, goat, horse, and sheep.  A tolerance of
0.01 ppm each has been established for hog fat, meat, and meat
byproducts.  A milk tolerance of 0.006 ppm is also established.  No
tolerances for eggs and poultry meat and meat byproducts have been
established.  

The livestock feedstuffs associated with this petition are barley grain
and straw; in addition, there are established tolerances for numerous
livestock feedstuffs.  Using Table 1 Feedstuffs (June 2008) and
constructing reasonably balanced livestock diets, the estimated
livestock dietary burdens of azoxystrobin are presented in Table 5
(email, J. Stokes, 07/22/2009).  

 

Table 5.	Calculation of Dietary Burdens of Azoxystrobin Residues to
Livestock.

Feedstuff	Type1	% Dry Matter2	% Diet2	Recommended/

Established Tolerance (ppm)	Dietary Contribution (ppm)3

Beef Cattle

Alfalfa hay 	R	89	15	120	20.2

Aspirated grain fractions	CC	85	5	420	24.7

Barley grain	CC	88	35	3.0	1.19

Sorghum grain	CC	86	40	11	5.12

Canola meal	PC	88	5	1.0	0.057

TOTAL BURDEN	--	--	100	--	51.3

Dairy Cattle

Alfalfa hay	R	89	20	120	27.0

Corn, field, silage	R	40	25	12	7.5

Sorghum grain	CC	86	45	11	5.76

Canola meal	PC	88	10	1.0	0.114

TOTAL BURDEN	--	--	100	--	40.4

Poultry

Sorghum grain	CC	86	75	11	8.25

Alfalfa meal	PC	89	5	120	6.0

Cottonseed meal 	      PC	88	20	0.6	0.12

TOTAL BURDEN	--	--	100	--	14.4

Swine

Barley grain	CC	88	5	3.0	0.15

Sorghum grain	CC	86	80	11	8.8

Alfalfa meal	PC	89	5	120	6.0

Soybean meal 	      PC	92	10	0.5	0.05

TOTAL BURDEN	--	--	100	--	15.0

1  R:  Roughage; CC:  Carbohydrate concentrate; PC:  Protein
concentrate.

2  OPPTS 860.1000 Table 1 Feedstuffs (June 2008).  

3  Contribution = ([tolerance /% DM] X % diet) for beef and dairy
cattle; contribution = ([tolerance] X % diet) for poultry and swine. 

Comments

1) Alfalfa hay is chosen because it is the most widely used hay for
cattle across the US.

2) Normally alfalfa hay will be given over alfalfa forage mainly because
many production animals are in confined           spaces and not grazing
on pastures.

3) Canola and cottonseed meals are listed in diets, but could also
replace with soybean meal and not affect the   proposed diets and total
dietary burdens.

4) Rice grain could replace the barley grain for swine, but would not
affect the total estimated dietary burden.

Adequate livestock feeding studies have been submitted previously for
azoxystrobin.  A dairy cattle feeding study was reviewed in conjunction
with PP#6F4762 and a study with laying hens was reviewed in conjunction
with PP#7F4864.  In the cattle feeding study, cattle were dosed at
levels of 5, 25, 75, and 250 ppm for 28-30 consecutive days.  The dosing
levels represent ~0.1x, 0.5x, 1.5x, and 4.9x the dietary burden for beef
cattle, ~0.1x, 0.6x, 1.9x, and 6.2x the dietary burden for dairy cattle,
and ~0.3x, 1.7x, 5x, and 16.7x the dietary burden for swine.  Milk and
tissue samples were analyzed for residues of azoxystrobin using the
enforcement method for livestock commodities, with LOQs of 0.001 ppm for
milk and 0.01 ppm for tissues and cream.  The results of the cattle
feeding study are summarized in Table 6.  

In the poultry study, hens were dosed at levels of 60 ppm for 28
consecutive days; the dosing level represents 4.2x the dietary burden to
poultry (the study included lower dose rates of 6.0 and 18 ppm; however,
these samples were not analyzed).  Egg and tissue samples were analyzed
for residues of azoxystrobin using the enforcement method for livestock
commodities, with an LOQ of 0.01 ppm for each matrix.  No quantifiable
residues were found in any poultry commodity (see Table 6).

Table 6.	Summary of Azoxystrobin Residues in Livestock Matrices
Following the Oral Administration of Azoxystrobin over 28-30 Consecutive
Days.

Dose Rate in Diet (mg/kg)	Azoxystrobin Residues (ppm)

	Milk/Eggs	Muscle	Fat	Kidney	Liver

Dairy Cattle

5	<0.001-0.003	<0.01	<0.01	<0.01	<0.01

25	<0.001-0.006	<0.01	<0.01	<0.01	<0.01-0.01

75	<0.001-0.004	<0.01	<0.01-0.03	<0.01-0.01	0.01-0.05

250	0.002-0.009	<0.01	0.01-0.03	0.01-0.02	0.03-0.07

Laying Hens

60	<0.01	<0.01	<0.01	Not analyzed	<0.01



Conclusions:  The existing azoxystrobin tolerances for milk and the fat,
meat, and meat byproducts of cattle, goat, hog, horse, and sheep are
adequate; no revision to the existing tolerances is needed to support
the proposed uses of azoxystrobin.  

The proposed uses of azoxystrobin addressed in this document do not
alter the Agency’s previous conclusion that there is no reasonable
expectation of finite residues in poultry commodities [Category 3 of
§180.6(a)].  No tolerances are needed for poultry tissues or eggs.  

860.1500 Crop Field Trials

Barley

DER Reference:	47486501.der.doc

PP#9F6058; DP# 260134, 9/6/00, M. Nelson 

PP#s 6F7106 & 7F7198; DP# 334571 & 340016, 3/12/08, W. Cutchin

Tolerances have been established for the combined residues of
azoxystrobin and its Z-isomer in/on barley commodities at 25 ppm for
barley forage, 15 ppm for barley hay, 0.1 ppm for barley grain, and 4.0
ppm for barley straw [40 CFR §180.507(a)(1)].  The tolerances were
established based on translation of residue data from wheat (PP#s 9F6058
and 6F7106).  The available wheat data support use of SC and WDG
formulations on barley at a maximum seasonal rate of 0.40 lb ai/A, with
a 14-day PHI for forage and hay and a 45-day PHI for grain and straw.  

IR-4 has submitted field trial data to support a reduced PHI for barley
grain and straw with regional restrictions; four barley field trials
were conducted in the United States in Zones 8 (CO; 2 trials) and 11
(ID; 2 trials) during the 2004 and 2005 growing seasons.

Each trial consisted of one untreated and two treated plots.  Both
treated plots received two foliar broadcast applications, with an 11- to
14-day retreatment interval, of a 2.08 lb ai/gal SC formulation of
azoxystrobin at 0.192-0.207 lb ai/A/application for a total seasonal
rate of 0.391-0.411 lb ai/A (1x the proposed maximum seasonal rate). 
Applications were made using ground equipment in 29-36 gal/A spray
volumes; no adjuvant was added to the spray mixtures.  Mature grain and
straw were harvested 14-15 days after the last application from one
treatment plot, and 21-23 days after last application from the other
treatment plot.  Applications at the plot with the shorter PHI were made
to barley at later growth stages, so that mature crops were collected on
the same day from all plots.  HED notes that applications to barley were
made at crop growth stages after forage and hay would typically be
collected.

Samples of barley grain and straw were analyzed for residues of
azoxystrobin and its Z-isomer using LC/MS/MS Method 305/03.  The method
was adequate for data collection based on acceptable concurrent method
validation recoveries.  The LLMV for barley grain and straw was 0.01 ppm
for each analyte.

Samples of barley grain and straw were stored frozen from harvest to
analysis for up to 366 days (12 months).  Adequate storage stability
data are available to support the storage conditions and durations of
samples from the barley field trials.

The residue data for barley grain and straw are summarized in Table 7. 
Maximum residues of azoxystrobin and its Z-isomer, respectively, were
2.0 and 0.18 ppm in/on barley grain and 3.3 and 0.26 ppm in/on barley
straw harvested 14-15 days following foliar applications of the 2.08 lb
ai/gal SC formulation at a total rate of 0.392-0.403 lb ai/A.  Maximum
total azoxystrobin and its Z-isomer residues were 2.2 ppm in/on barley
grain and 3.6 ppm in/on barley straw.

Residues of azoxystrobin and its Z-isomer were lower in barley samples
treated at earlier growth stages and harvested with a longer PHI. 
Maximum residues of azoxystrobin and its Z-isomer, respectively, were
1.5 and 0.14 ppm in/on barley grain, and 2.9 and 0.32 ppm in/on barley
straw harvested 21-23 days following foliar applications of the 2.08 lb
ai/gal SC formulation at a total rate of 0.391-0.411 lb ai/A.  Maximum
total azoxystrobin and its Z-isomer residues were 1.6 ppm in/on barley
grain, and 3.2 ppm in/on barley straw.

Table 7.	Summary of Residue Data from Crop Field Trials with
Azoxystrobin.

Commodity	Total Applic. Rate

 (lb ai/A)	PHI (days)	Analyte	Residue Levels (ppm)





n	Min.	Max.	HAFT1	Median	Mean	Std.

Dev.

Barley (proposed use = 0.40 lb ai/A total application rate, 14-day PHI
for grain and straw grown in AZ, CO, western MT, NM, NV, ID, OR, west
TX, UT, WA, and western WY)

Barley, grain	0.392-0.403	14-15	Azoxystrobin	8	0.75	2.0	1.7	1.25	1.26
0.44



	Z-isomer	8	0.07	0.18	0.15	0.11	0.11	0.04



	Total	8	0.82	2.18	1.85	1.36	1.37	0.48

	0.391-0.411	21-23	Azoxystrobin	8	0.09	1.5	1.5	0.72	0.82	0.59



	Z-isomer	8	<0.01	0.14	0.14	0.07	0.08	0.05



	Total	8	<0.10	1.64	1.64	0.79	0.90	0.64

Barley, straw	0.392-0.403	14-15	Azoxystrobin	8	0.72	3.3	3.3	1.85	1.90
0.99



	Z-isomer	8	0.06	0.26	0.26	0.15	0.15	0.08



	Total	8	0.78	3.56	3.56	2.00	2.05	1.07

	0.391-0.411	21-23	Azoxystrobin	8	0.47	2.9	2.7	1.90	1.80	0.99



	Z-isomer	8	0.03	0.32	0.31	0.15	0.16	0.12



	Total	8	0.50	3.22	2.96	2.10	1.96	1.11

1 HAFT = Highest Average Field Trial.

Conclusions.  The submitted barley field trial data are adequate to
satisfy data requirements provided the proposed use is amended as
requested under 860.1200.  The trials were conducted in Zones 8 and 11;
the trials conducted in Zone 8 were conducted very close to the border
between Zones 8 and 9.  The areas of the country for which the reduced
PHI was proposed by IR-4 represent Zones 8, 9, 10, 11, and 12.  Under
860.1500 (Attachment 11), the guidelines specify that for geographically
restricted registrations, the number of trials required equals the
number of trials for a national registration multiplied by the
proportion (by acres) of the crop grown in that region.  Therefore, 4
trials would be required for barley use in Zone 8, 9, 10, 11, and 12
[twelve trials required for national registration x 30% total regional
distribution in Zones 8 (2%), 9 (6%), 10 (3%), 11 (19%), and 12 (no
significant production) equals four trials].  Two trials were conducted
in 2004 and the other two trials were conducted in 2005, representing
multiple year data as also required for geographically restricted
registrations.

The submitted crop field trial would support increased tolerances of 3.0
ppm for barley grain and 7.0 ppm for barley straw; refer to Appendix I
for the tolerance calculations.  

Head and stem Brassica vegetable subgroup 5A

PP#s 2E6489, 2E6495, and 2E6488; DP#s 285603, 285606, 285607, 285608;
1/22/03; N. Dodd

A tolerance of 3.0 ppm has been established for the combined residues of
azoxystrobin and its Z-isomer in/on the head and stem Brassica subgroup
[40 CFR §180.507(a)(1)].  The tolerance was based on residue data for
broccoli and cabbage reflecting foliar applications of a 80% WDG
formulation at a total seasonal rate of 1.50 lb ai/A, with a 0-day PHI. 


Syngenta has proposed seed treatment use of the 0.83 lb ai/gal SC
formulation on head and stem Brassica vegetables at a maximum rate of
0.024 lb ai/100 lb seed.  The treatment rate corresponds to a field
equivalent rate of 0.0012 lb ai/A [calculated using the maximum head and
stem Brassica seeding rate of 5 lb/A, specified for kohlrabi in HED
EXPOSAC SOP 15 (“Amount of Seed Treated or Planted Per Day,”
3/2/04)].  Because the proposed seed treatment use rate is much lower
than the registered foliar use rate, no additional data will be required
to support seed treatment uses on head and stem Brassica vegetables. 
All Syngenta products with foliar uses on head and stem Brassica specify
that no more than 1.50 lb ai/A per season of azoxystrobin-containing
products be applied to head and stem Brassica crops.

Conclusions.  The proposed seed treatment use on head and stem Brassica
subgroup 5A is not expected to increase residue levels in treated head
and stem Brassica matrices; therefore, no change to the established
tolerance is needed.  The maximum seasonal rate from application of any
azoxystrobin-containing products remains unchanged. 

Sorghum, Grain

PP#s 6F7106 & 7F7198; DP# 334571 & 340016, 3/12/08, W. Cutchin

Tolerances have been established for the combined residues of
azoxystrobin and its Z-isomer in/on sorghum, grain commodities at 25 ppm
for forage, 11 ppm for grain, and 40 ppm for stover [40 CFR
§180.507(a)(1)].  In addition, a tolerance has been established for
aspirated grain fractions at 420 ppm.  The tolerances were based on
residue data for sorghum, grain commodities reflecting foliar
applications of a 2.08 lb ai/gal SC formulation at a total seasonal rate
of ~0.50 lb ai/A for sorghum, grain, forage, and ~0.75 lb ai/A for grain
and stover, with a 14-day PHI.  

Syngenta has proposed seed treatment use of the 0.83 lb ai/gal SC
formulation on sorghum, grain at a maximum rate of 0.020 lb ai/100 lb
seed.  The treatment rate corresponds to a field equivalent rate of
0.002 lb ai/A (calculated using the seeding rate of 10 lb/A, specified
for sorghum, grain in HED EXPOSAC SOP 15).  Because the proposed seed
treatment use rate is much lower than the registered foliar use rate, no
additional data will be required to support seed treatment use on
sorghum, grain.  All Syngenta products with foliar uses on sorghum,
grain specify that no more than 0.50 lb ai/A per season of
azoxystrobin-containing products be applied to sorghum, grain grown for
forage and no more than 0.75 lb ai/A per season of
azoxystrobin-containing products be applied to sorghum, grain grown for
grain and stover.  

Conclusions.  The proposed seed-treatment use on sorghum, grain is not
expected to increase residue levels in treated matrices; therefore, no
changes to the established tolerances for sorghum, grain commodities are
needed.  The maximum seasonal rate from application of any
azoxystrobin-containing products remains unchanged. 

HED notes that additional field trial data were required to support
in-furrow applications of azoxystrobin to sorghum, grain in conjunction
with PP#s 6F7106 & 7F7198.  These data have not yet been submitted (due
date for the bridging studies is 07/10/2011).

860.1520 Processed Food and Feed

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney

DP# 254140, 3/17/99, G. J. Herndon

No new processing studies were submitted with this petition.  Residue
data are not required for any processed commodities of head and stem
Brassica vegetables or sorghum, grain.  

RAB2 (L. Kutney, 04/25/97; DPs# 230634-637) previously concluded that it
was appropriate to establish tolerances on barley processed commodities
based on wheat processing data.  In a wheat processing study submitted
under PP#6F4762, residues of azoxystrobin were found to concentrate in
wheat bran (3x) but not in wheat middlings, shorts, germ, and flour. 
Processing factors for the Z-isomer could not be determined because
residues of the Z-isomer were nonquantifiable in wheat grain and its
processed commodities.  Based on the available wheat processing data, a
tolerance for barley bran was established at 0.2 ppm.  The proposed
reduced PHI for barley grain results in higher residues in the grain,
and therefore the potential for increased residues in barley bran. 
Using the HAFT for barley grain harvested at the 14-day PHI  (1.85 ppm)
and the concentration factor for wheat bran (3x), expected residues in
barley bran would be 5.55 ppm, which exceeds the recommended increased
tolerance of 3 ppm for barley grain and the existing tolerance of 0.2
ppm for barley bran.  Therefore, an increased tolerance is needed for
barley bran at 6.0 ppm.

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

Analytical standards for azoxystrobin and its Z-isomer are currently
available in the EPA National Pesticide Standards Repository (personal
communication with Dallas Wright, ACB, 4/29/09) with 1/1/2011 and
3/31/2010 expiration dates, respectively. 

860.1850 Confined Accumulation in Rotational Crops

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney

PP#9F6058; DP# 260134, 9/6/00, M. Nelson 

  SEQ CHAPTER \h \r 1 Adequate confined studies have previously been
presented in PP#6F4762 and re-evaluated in PP#9F6058.  Total radioactive
residues, expressed as [14C]azoxystrobin equivalents, accumulated at
>0.01 ppm in the raw agricultural commodities of lettuce, radishes, and
wheat planted in sandy loam soil 30, 200, and 365 days after treatment
of the soil with [14C]azoxystrobin at 1.8 lb ai/A.  Residues were
highest in rotated crop commodities from the 30-day PBI and declined in
subsequent PBIs.  

Azoxystrobin was identified in all rotated crop commodities at the
30-day PBI.  In 30-day PBI samples, the Z-isomer was only identified in
wheat forage and straw.  Compound 42 was the major metabolite identified
in 30-day PBI lettuce and wheat forage and straw.  In 30-day PBI radish
roots, azoxystrobin was the major metabolite and in 30-day PBI radish
tops, metabolites G2, N1, and N2 were the major metabolites.  In 30-day
PBI wheat grain, 14C-starch was found to account for the largest portion
of radioactivity.  Several conjugated metabolites (compound 42 and the
M, N, and O metabolites) of primary crop metabolites were identified,
indicating that azoxystrobin is more extensively metabolized in
rotational crops than in primary crops.  HED has concluded that the
residues of concern in rotational crops are parent and the Z-isomer.

860.1900 Field Accumulation in Rotational Crops

PP#6F4762; DP#s 230634, 230635, 230636, and 230637; 4/25/97; L. Kutney 

PP#9F6058; DP#s 283588 and 287062, 2/6/03, N. Dodd

PP#9F6058; DP# 298114, 12/20/05, L. Cheng 

PP#s 6F7106 & 7F7198; DP# 334571 & 340016, 3/12/08, W. Cutchin

Limited field rotational crop studies, reflecting applications made to
the primary crop at a seasonal rate of 0.8 lb ai/A, were initially
submitted in PP#6F4762.  Subsequently, additional limited field
rotational crop studies, with applications made to the primary crop at
seasonal rates of 1.6 or 2.0 lb ai/A, were submitted and reviewed in
PP#9F6058.  Under PP#s 6F7106 and 7F7198, HED concluded that the
following PBIs were appropriate to support a maximum seasonal
application rate of 2.0 lb ai/A to rotated crops:  12 months for
buckwheat, millet, oats and rye; and 36 days for the leafy vegetables
(except Brassica) crop group; the Brassica leafy greens subgroup; the
root vegetables subgroup; the tuberous and corm vegetable subgroup; and
the leaves of root and tuber vegetables group.  Crops with registered
uses may be planted immediately after the last treatment unless
otherwise specified.  For crops not on the label, a 12-month PBI must be
observed unless otherwise specified. 

Conclusions:  Because the proposed amended uses on barley, the head and
stem Brassica subgroup, and sorghum, grain do not result in increased
maximum seasonal application rates of azoxystrobin, no changes to the
existing rotational crop restrictions are needed.  Provided the
recommended revision under General Information (General Use Precautions)
for EPA Reg. Nos. 100-1098 is submitted, the rotational crop
restrictions on the labels for EPA Reg. Nos. 100-1098 and 100-1159 are
adequate.  

860.1550 Proposed Tolerances

HED has determined that the residues of concern in/on crop commodities
for tolerance expression and risk assessment purposes are azoxystrobin
and its Z-isomer.  The tolerance expression proposed by IR-4 for the
revised barley tolerances is adequate.  

Adequate field trial data have been submitted for barley.  The
Agency’s Guidance for Setting Pesticide Tolerances Based on Field
Trial Data was utilized for determining appropriate tolerance levels for
barley grain and straw; see Appendix II for tolerance calculations.  The
available data will support the proposed tolerances of 3.0 ppm for
barley, grain and 7.0 ppm for barley, straw; see Table 8.  

The proposed reduced PHI for barley grain results in higher residues in
the grain, and therefore the potential for increased residues in barley
bran.  The available data support an increased tolerance of 6.0 ppm for
barley, bran.  

The proposed seed-treatment uses on head and stem Brassica vegetables
and sorghum, grain are not expected to have an impact on residues in the
related commodities; therefore, no changes are needed to the established
tolerances for the commodities of head and stem Brassica subgroup 5A and
sorghum, grain.  

No changes to the existing tolerances for livestock commodities are
needed as a result of the proposed uses.

Table 8. 	Tolerance Summary for Azoxystrobin

Commodity	Established Tolerance (ppm)	Proposed Tolerance (ppm)
Recommended Tolerance (ppm)	Comments; Correct Commodity Definition

Barley, bran	0.2	--	6.0

	Barley, grain	0.1	3.0	3.0

	Barley, straw	4.0	7	7.0

	

Codex maximum residue limits (MRLs) have been established for
azoxystrobin in barley, grain (0.5 ppm) and straw and fodder (dry) of
cereal grains (except maize) at (15 ppm).  There are no Canadian MRLs
for residues of azoxystrobin and its (Z)-isomer for the requested crops.
 Mexican MRLS have been established for residues of ‘azoxistrobin’;
MRLs have been established for barley, grain (0.3 ppm).  Refer to
Appendix I.

The Codex MRLs for barley grain and straw are based on trials conducted
in Europe and on residues present at a 35-42 day PHI.  The recommended
US tolerances on barley grain (3.0 ppm) and straw (7.0 ppm) are based on
residues present at a 14-day PHI.  The US MRL for grain is higher due to
shorter PHI.  The Codex MRL for straw is for cereal grains straw and
encompasses barley, corn, sweet corn, oats, rice, and wheat data from
Europe.  Moreover, Codex MRLs for forages, straws, and the like are set
on a dry-weight basis, whereas US tolerances are set on an as-fed basis.

References

DP#s:	218318 and 218448

Subject:	PP No. 5F4541:  New Chemical:  Azoxystrobin (ICIA5504) in/on
Grape RACs.  Evaluation of Analytical Methods and Residue Data.  CBTS
Nos. 16051 & 16092.

From:	J. Garbus

To:	J. Bazuin/C. Giles-Parker

Dated:	3/19/96

MRIDs:	43678102-43678107, 43678193-43678195, 43678200-43678210 and
43694201-43694206

DP#s:	230634, 230635, 230636, and 230637

Subject:	PP#6F4762.  Azoxystrobin.  Permanent Tolerance Petition for Use
on Bananas, Peaches, Peanuts, Tomatoes, and Wheat.  Evaluation of
Analytical Methodology and Residue Data.  Chemical# 128810.  CBTS#:
None.

From:	L. Kutney

To:	C. Giles-Parker, J. Bazuin, and B. Madden

Dated:	4/25/97

MRIDs:	44058715-44058730, 44058732-44058736, and 44073203-44073205

DP#s:	248887 and 249671

Subject:	PP#7F4864.  Tolerance Petition for use of Azoxystrobin on
Cucurbits. PP#8F4995.  Tolerance Petition for use of Azoxystrobin on
Bananas, Potatoes, and Stone Fruits.

From:	D. Dotson, M. Doherty, and Y. Donovan

To:	C. Giles-Parker/J. Bazuin

Dated:	10/14/98

MRIDs:	44319305, 44452303, 44595105, 44595109-44595111, 44595114,
44595116, 44613501, and 44613503

DP#:	251683

Subject:	Azoxystrobin.  Conclusions of the Metabolism Assessment Review
Committee at Meeting of 11/10/98.

From:	W. Wassell

To:	G. F. Kramer, MARC

Dated:	12/30/98

MRIDs:	None

DP#s:	249657 and 249668

Subject:	PP# 7F4864.  Tolerance Petition for use of Azoxystrobin on
Peanut Hay, Pistachios, Rice, Tree Nuts, and Wheat.  PP# 8F4995. 
Tolerance Petition for use of Azoxystrobin on Canola.

From:	D. Dotson

To:	C. Giles-Parker/J. Bazuin

Dated:	1/25/99

MRIDs:	44319303, 44319304, 44319306-44319308, 44452303,
44595104-44595108, 44595113, 44595115 and 44613502

DP#:	254140

Subject:	Azoxystrobin on Various Commodities.  IR-4 Proposal For Reduced
Residue Chemistry Data Set.

From:	G. J. Herndon

To:	H. Jamerson/R. Forrest

Dated:	3/17/99

MRIDs:	44915206-32 and 44983101

DP#:	260134

Subject:	PP#9F06058:  Azoxystrobin.  Evaluation of Residue Chemistry
Data to Support Permanent Tolerances for Use of Azoxystrobin on Barley,
Bulb Vegetables, Cilantro, Citrus Fruits, Corn, Cotton, Leafy Vegetables
(Except Brassica), Leaves of Root and Tuber Vegetables, Peanuts, Root
and Tuber Vegetables, Soybeans, and Wild Rice; Higher Tolerances for the
Fat and Meat Byproducts of Cattle, Goats, Horses and Sheep; and, apples
(Inadvertent Residues).

From:	M. J. Nelson

To:	J. Bazuin/C. Giles-Parker

Dated:	9/6/00

MRIDs:	44915206-44915232 and 44983101

DP#s:	285603, 285606, 285607 and 285608

Subject:	PP#s 2E06489, 2E06495, 2E06375, and 2E06488.  Azoxystrobin. 
IR-4 Permanent Tolerance Petitions with Field Trials on Globe Artichoke,
Asparagus, Basil, Broccoli, and Cabbage.  Summary of Analytical
Chemistry and Residue Data.

From:	N. Dodd

To:	S. Brothers/R. Forrest

Dated:	1/22/03

MRIDs:	45544901, 45730101, 45730102, 45731301, and 45736301 

DP#s:	283588 and 287062

Subject:	PP#9F06058 and ID#s 000100-01098 and 000100-01093. 
Azoxystrobin.  Condition-of-Registration Data, Including Bridging Data
from the 50 WDG Formulation to the 2.08 FlC Formulation on Spinach,
Garden Beet, Green Onion and Celery; Storage Stability Data; and Limited
Field Rotational Crop Data.

From:	N. Dodd

To:	J. Bazuin/C. Giles-Parker

Dated:	2/6/03

MRIDs:	45640301, 45640302, 45640304-46560307, and 45738101

DP#:	298114

Subject:	Azoxystrobin.  Heritage Fungicide (EPA Reg. No. 100-1093. 
Condition-of-Registration Data:  Limited Field Rotational Crop Data. 
Petition Number 9F6058.

From:	L. Cheng

To:	J. Bazuin/C. Giles-Parker

Dated:	12/20/05

MRIDs:	45872401

DP#s:	334571 and 340016

Subject:	Azoxystrobin.  Petitions for the Establishment of Permanent
Tolerances for New/Amended Uses on Non-grass Animal Feeds (Crop Group
18), Sorghum, Wheat, Cotton and Wild Rice.  PP#s 6F7106 & 7F7198. 
Summary of Analytical Chemistry and Residue Data.

From:	W. Cutchin

To:	S. Piper and T. Kish/J. Bazuin

Dated:	3/12/08

MRIDs:	46924301-46924303, 47096401-47096402

  SEQ CHAPTER \h \r 1 Attachments:  

Appendix I - International Residue Limit Status Sheet

Appendix II - Tolerance Assessment Calculations

Template Version September 2005

Appendix I - International Residue Limit Status Sheet.

INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name:  methyl(E)-2-(2-(6-(2-cyanophenoxy)
pyrimidin-4-yloxy)phenyl)-3-methoxyacrylate	Common Name:

Azoxystrobin	( Proposed tolerance

X Reevaluated tolerance

( Other	Date: 07/16/09

Codex Status (Maximum Residue Limits)	U. S. Tolerances

(    No Codex proposal step 6 or above

(    No Codex proposal step 6 or above for the crops requested	Petition
Number:  PP#8E7474

DP#s:  362963 & 363046

Other Identifier:  

Residue definition (step 8/CXL):  Azoxystrobin	Reviewer/Branch:  Meheret
Negussie, RAB3

	Residue definition in PP#8E7474

for plant commodities:  Combined residues of azoxystrobin and its
Z-isomer

 No Limits

√No Limits for the crops requested.	 No Limits

 No Limits for the crops requested

Residue definition  (αE)-methyl
2-[[6-(2-cyanophenoxy)-4-pyrimidinyl]oxy]-α
-methoxymethylene)benzeneacetate,

including the isomer (Z)-methyl 2-[[6-(2-

cyanophenoxy)-4-pyrimidinyl]oxy]--(methoxymethylene)benzeneacetate
Residue definition:  Azoxistrobin

Crop(s)	MRL (mg/kg)	Crop(s)	MRL (mg/kg)



Barley	0.3











Notes/Special Instructions:  Codex barley value based on European trials
only:  Combined azoxystrobin residues in barley grain from the trials in
Europe (n = 38), in ranked order median underlined, were: 0.01 (4), 0.02
(6), 0.03 (4), 0.04 (3), 0.05, 0.08 (3), 0.09, 0.10 (2),0.11 (4), 0.12,
0.13 (4), 0.14, 0.19, 0.20, 0.23, and 0.28 mg/kg. Typical label in
Europe is 2 X 0.25 kg ai/ha, 35 day PHI.

	

No information is available of the derivation of the Mexican MRL for
barley, 0.3 ppm.  This is from 2004 and may have changed.  Mexico
typically adopts Codex or US standards for its export purposes.

S.Funk, 07/17/2009.



Appendix II.  Tolerance Assessment Calculations.

The datasets used to establish a tolerance for combined residues of
azoxystrobin and its Z-isomer on barley grain and straw consisted of
field trial data representing application rates of ~0.40 lb ai/A (two
applications at ~0.20 lb ai/A/application) with a 14- to 15-day PHI.  As
specified by the Guidance for Setting Pesticide Tolerances Based on
Field Trial Data (SOP), the field trial application rates and PHIs are
within 25% of the maximum label application rate and minimum label PHI,
respectively.  The residue values that were entered into the tolerance
spreadsheet are provided in Table II-1.

All 8 field trial sample results for each matrix were above the LOQ (LOQ
= 0.01 ppm for each analyte).  Visual inspection of the lognormal
probability plots (Figures II-1 and II-3) and the results from the
approximate Shapiro-Francia test statistic (Figures II-2 and II-4)
indicated that the dataset was reasonably lognormal.  

Since the field trial data for azoxystrobin on barley grain and straw
represent small datasets (i.e., less than 15 samples) and are reasonably
lognormal, the upper bound estimate of the 95th percentile based on the
median residue value was compared to the minimum of the 95% upper
confidence limit (UCL) on the 95th percentile and the point estimate of
the 99th percentile, and the minimum value was selected as the tolerance
value.  Using the rounding procedure as outlined in the SOP, the
recommended tolerances for combined residues of azoxystrobin and its
Z-isomer in/on barley grain and straw are 3.0 ppm and 7.0 ppm,
respectively.  

Table II-1.	Residue data used to calculate tolerance for azoxystrobin on
barley grain and straw.

Regulator:	EPA	EPA

Chemical:	Azoxystrobin	Azoxystrobin

Crop:	Barley grain	Barley straw

PHI:	14-15 Days	14-15 Days

App. Rate:	0.392-0.403 lb ai/A	0.392-0.403 lb ai/A

Submitter:	IR-4	IR-4

MRID Citation:	MRID 47486501	MRID 47486501

	Combined Residues of Azoxystrobin and its Z-Isomer (ppm)

	0.82	2.0

	0.95	2.3

	1.4	1.1

	1.9	1.2

	0.93	0.78

	1.3	2.0

	1.5	3.6

	2.2	3.6



Figure II- 1.  Lognormal probability plot of azoxystrobin field trial
data for barley grain.  

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Figure II- 3.  Lognormal probability plot of azoxystrobin field trial
data for barley straw.  

Figure II- 4.  Tolerance spreadsheet summary of azoxystrobin field trial
data for barley straw.  

Page   PAGE  19  of   NUMPAGES  25 

Azoxystrobin	Summary of Analytical Chemistry and Residue Data	DP#s: 
362963 & 363046

