Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: March-21-2013 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Azoxystrobin. Revised Section 3 Petitions for the Establishment of Tolerances on 

Imported Ginseng (PP#1E7945), Rye, and Oats (PP#2F7976), and Section 3 

Amendments to Revise the Established Tolerances on Cereal Grains (Barley and 

Wheat) Due to Changes of Pre-Harvest Intervals (PP# 2F7984). Summary of 

Analytical Chemistry and Residue Data. 

PC Code: 128810 DP Barcodes: D397692, D400604, D400626 

Registration Nos.: 100-1098, 100-1178, 100-

1324 

Decision Nos.: 458947, 459651, 460759 

Regulatory Action: Tolerance Petition 

Petition Nos.: 1E7945, 2F7976, 2F7984 

Risk Assessment Type: N/A Case No.: N/A 

TXR No.: N/A CAS No.: 131860-33-8 

MRID Nos.: See MRID Summary Table 40 CFR: §180.507 

FROM: Meheret Negussie, Chemist / 1e,/,e.v-d ,Je0 W'I-t "><L 

Risk Assessment Branch III 

Health Effects Division (HED 7509P) 

THROUGH: Steve Funk, Senior Chemist /j ?f!- . Christine Olinger, Branch Chief , /}j( ... ~ ·, 

Risk 

Health 

Assessment 

Effects Division 

Branch 

(HED 

III 

7509P) 

{_;k-7-, ~ 

TO: Erin Malone/Marcel Howard, RM# 20 

Fungicide Branch 

Registration Division (7505P) 

Note: The DERs were originally prepared under contract by Versar, Inc. (6850 Versar Center, 

Springfield, VA 22151; submitted 5/23112). The document has been reviewed by the Health 

Effects Division (HED) and revised to reflect current Office of Pesticide Programs (OPP) 

Page 1 of 58 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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policies. This document reflects revisions to a previous version (Oct-11-2012) to the tolerance 

recommendations. 

MRID Summary Table 

MRID No. Study Type Comments 

48601201 860.1500 Ginseng (Korea) New DER; 48601201.der (includes review of 48601202) 

48601202 

48601203 860.1500 Ginseng (Korea)) New DER; 48601203.der 

48681701 860.1500 Rye New DER; 48681701.der.doc 

48681702 860.1500 Barley New DER; 48681702.der.doc 

48681703 860.1500 Oats New DER; 48681703.der.doc 

48681704 860.1500 Wheat New DER; 48681704.der.doc 

48681704 860.1520 Wheat New DER; 48681704.der1.doc 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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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), suspension concentrate (SC; previously referenced as flowable 

concentrate), and soluble emulsion (SE) formulations. These products may be applied as infurrow 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#1E7945, Syngenta Crop Protection, Inc. (Syngenta) has requested the establishment of 

an import tolerance for the residues of azoxystrobin [methyl(E)-2-(2-(6-(2-

cyanophenoxy)pyrimidin-4-yloxy)phenyl)-3-methoxyacrylate] and the Z-isomer of azoxystrobin, 

[methyl(Z)-2-(2-(6-(2-cyanophenoxy)pyrimidin-4-yloxy)phenyl)-3-methoxyacrylate] in/on the 

following agricultural commodities: 

Ginseng Extract 

(Red Ginseng Extract and Ginseng Extract) ............0.5 ppm 

Under PP#2F7976 Syngenta has requested the establishment of tolerances for the residues of 

azoxystrobin and its Z-isomer in/on the following agricultural commodities: 

Oat, forage ................................................................4 ppm 

Oat, hay ....................................................................7 ppm 

Oat, straw .................................................................3 ppm 

Oat, grain..................................................................1 ppm 

Rye, forage ...............................................................4 ppm 

Rye, straw...............................................0.8 ppm 

Rye, grain ..............................................0.07 ppm 

Under PP# 2F7984 Syngenta is requesting revision of the established tolerances on wheat and 

barley commodities as follows: 

Barley, hay ...............................................................7 ppm 

Barley, straw ............................................................8 ppm 

Barley, grain .............................................................2 ppm 

Wheat, forage .........................................................10 ppm 

Wheat, straw ............................................................6 ppm 

Wheat, hay .............................................................20 ppm 

Grain, Aspirated fractions...........................460 ppm 

Concurrently, Syngenta requests to amend the tolerances for the following livestock 

commodities as follows: 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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Cattle, fat................................................0.3 ppm 

Hog, fat...................................................0.1 ppm 

Hog, meat................................................0.02 ppm 

In addition, Syngenta requests to establish tolerances for the following livestock commodities: 

Poultry, meat...........................................0.01 ppm 

Poultry, liver..............................................0.2 ppm 

Poultry, fat..............................................0.01 ppm 

Egg.........................................................0.1 ppm 

Cattle, liver................................................0.5 ppm 

Cattle, Kidney............................................0.1 ppm 

Hog, liver...................................................0.2 ppm 

Hog, kidney.............................................0.03 ppm 

In support of the requested import tolerance, Syngenta has submitted a draft label with English 

translations for the 20% SC formulation of azoxystrobin (Azoxystrobin SC; Ortiva) reflecting 

established use patterns in Korea. Based on the submitted label and Section B of the petition, the 

20% SC is proposed for up to four foliar applications to ginseng at 10 mL formulated product/20 

mL water with a 7-day pre-harvest interval (PHI). Additional information was received: 

azoxystrobin content changed from 20% to 21.7%; application spray volume (3500 L/ha); 

product rate (1750 g (ml)/ha); and single application rate (379.75 g/ha) (email communication 

Erin Malone, 10/09/12). Based on these information, the maximum seasonal application rate is 

1519 g ai/ha (1.36 lb ai/A). 

In conjunction with PP#2F7976 and PP# 2F7984, Syngenta is requesting amended registration of 

Abound® Flowable Fungicide (EPA Reg. No. 100-1098), Quilt® Fungicide (EPA Reg. No. 

100-1178), and Quilt Xcel® Fungicide (EPA Reg. No. 100-1324) to add uses on oats and rye. 

Quilt Xcel® Fungicide is a multiple active ingredient (MAI) suspo-emulsion (SE) formulation 

containing 1.18 lb ai/gal azoxystrobin and 1.02 lb ai/gal propiconazole. Quilt ® Fungicide is a 

MAI suspo-emulsion formulation containing 0.62 lb ai/gal azoxystrobin and 1.04 lb ai/gal 

propiconazole. The Abound® Flowable Fungicide is a SC formulation containing 2.08 lb ai/gal 

of azoxystrobin. Only data pertaining to azoxystrobin are reviewed in this document. 

 

For the new uses (oats and rye), the Abound® Flowable Fungicide is proposed for up to two 

foliar applications at 0.20 lb ai/A/application for a total seasonal application rate of 0.40 lb ai/A; 

Quilt® Fungicide is proposed for up to two foliar applications at 0.068 lb ai/A/application for a 

total seasonal application rate of 0.14 lb ai/A. Quilt Xcel® Fungicide is proposed for up to two 

foliar applications at 0.13 lb ai/A/application for a total seasonal application rate of 0.26 lb ai/A. 

Concurrently, in petition PP# 2F7984, the registrant is requesting to change the PHIs on the 

registered label for cereals (wheat, barley and triticale) from 14-30 days to PHIs of 7 days for 

forage and hay and remove the 45-day PHI for grain and straw and replace it with growth stage 

restriction for the last application on the aforementioned end use products. The limitation is to 

apply no later than Feekes Growth Stage 10.54. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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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. The established tolerances for plant 

commodities range from 0.01 ppm for pecan to 420 ppm for grain, aspirated fractions. 

Tolerances are currently established for barley bran (6.0 ppm), forage (25 ppm), grain (3.0 ppm), 

hay (15 ppm), and straw (7 ppm); wheat bran (0.20 ppm), forage (25 ppm), grain (0.10 ppm), 

hay (15 ppm), and straw (4 ppm). Tolerances for livestock commodities are established under 40 

CFR §180.507(a)(2) and are also expressed in terms of residues of azoxystrobin and its Zisomer; however, the Z-isomer should be removed from the tolerance expression. 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 livestock 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 Zisomer. The residue of concern in livestock is parent azoxystrobin only. 

For ginseng, an adequate residue analytical method is available for tolerance enforcement in crop 

commodities: a gas chromatography method with nitrogen-phosphorus detection (GC/NPD), 

RAM 243/04, for the analysis of crop commodities for residues of azoxystrobin. Samples from 

the submitted magnitude of the residue (MOR) studies were analyzed for residues of 

azoxystrobin using a gas liquid chromatography (GLC) method with electron capture (ECD); the 

method number was not reported. The method limits of quantitation (LOQs; determined as the 

lowest level of method validation, LLMV) were 0.003 or 0.02 ppm for ginseng fresh root and 

0.007 or 0.04 ppm for dried ginseng, red ginseng, and the extracts of dried and red ginseng. The 

method was adequate for data collection based on acceptable concurrent method recoveries, and 

the fortification levels used in concurrent method recovery were adequate to bracket expected 

residues. 

Samples from the submitted crop field trials (oats, rye, barley, and wheat) and processing study 

(wheat) were analyzed for residues of azoxystrobin and its Z-isomer (R230310) using an ultra 

performance liquid chromatography method with tandem mass spectrometry detection 

(UPLC/MS/MS), Method RAM 305/03. The limit of quantitation (LOQ; determined as the 

lowest level of method validation, LLMV) was 0.01 ppm for each analyte. The method was 

adequate for data collection based on acceptable concurrent recovery data. The fortification 

levels used in concurrent method recovery were adequate to bracket expected residue levels. 

The submitted crop field trial data for ginseng conducted in Korea are acceptable. The submitted 

ginseng crop field trials reflect the proposed use patterns. Samples from the ginseng studies 

were not analyzed for residues of the Z-isomer; therefore, the petitioner proposed a worst-case 

metabolic factor of 0.09x, determined from the existing root crop data reflecting analysis for 

residues of azoxystrobin and the Z-isomer. This factor was applied to the residue results for 

calculation of the recommended tolerance level for ginseng. Based on the submitted data, 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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reflecting 1- and 2-year applications and extrapolation of residues of azoxystrobin to account for 

the Z-isomer and using the OECD calculation procedures an import tolerance of 0.4 ppm for 

ginseng is recommended for residues resulting from use of azoxystrobin in Korea. HED is 

recommending a tolerance of 0.5 ppm on ginseng to harmonize with Codex. The Agency 

considers the raw agricultural commodity (RAC) of ginseng to be the dried root, defined as 

“ginseng” for tolerance purposes (refer to DP# 225494, dated 5/1/96, B. Schneider). 

The data from the ginseng field trial indicate that residues of azoxystrobin may concentrate in 

ethanol extracts and water extracts of dried and red ginseng processed from dried ginseng and 

red ginseng bearing quantifiable residues. 

The maximum expected residue of azoxystrobin in dried and red ginseng ethanol and water 

extracts were determined by multiplying the average processing factor by the HAFT residue of 

dried ginseng (1.8 x 0.193 = 0.35 ppm). Since this estimate is below the recommended tolerance 

for ginseng, a processed commodity tolerance is not needed. Furthermore, the Agency does not 

typically set tolerances on ginseng processed commodities. The petitioner needs to submit a 

revised section F to propose a tolerance on ginseng at 0.5 ppm. 

The submitted crop field trial data for oats, rye, barley, and wheat are acceptable pending 

submission of Section F. Although the number of field trials is technically inadequate (oats and 

rye), HED concludes that the available data are sufficient to support registration of azoxystrobin 

on oats and rye because the field trials conducted cover all zones requested. All other trials are 

adequate with respect to the number and locations of field trials. The crop field trial data for oats 

and rye reflect the proposed use patterns of (Quilt ® Fungicide (EPA Reg. No. 100-1178) and 

Quilt Xcel® Fungicide (EPA Reg. No. 100-1324)). The submitted crop field trials were 

conducted using the Quilt Xcel® with two foliar applications at 0.13 lb ai/A/application 

for a total seasonal application rate of 0.26 lb ai/A. The crop field trial data on oats and rye does 

not reflect the proposed use pattern of the Abound® Flowable Fungicide. The Abound® can be 

applied up to two foliar applications at 0.20 lb ai/A/application for a total seasonal application 

rate of 0.40 lb ai/A. The application rates used in the crop field trials are lower than the rates of 

the Abound® label. Therefore, residue levels were adjusted using the proportionality principle 

(ChemSac minutes 03/28/2012; JMPR report 2011) before deriving a tolerance level to reflect 

the proposed higher application rate. 

There are adequate existing storage stability data to validate the storage conditions and durations 

of samples from the submitted studies. 

The Organization for Economic Cooperation and Development (OECD) statistical calculation 

procedures were used to determine appropriate tolerance levels. Based on the available data, the 

proposed tolerances for oat and rye commodities must be revised to reflect the appropriate 

tolerance levels estimated using the OECD statistical calculation procedures. HED recommends 

a tolerance of 5, 10, 3, and 1.5 ppm for oat forage, hay, straw, and grain, respectively. The 

recommended tolerances for rye forage, straw, and grain are 7, 1.5, and 0.1 ppm, respectively. 

The proposed tolerances do not reflect the proposed highest application rate. A revised Section F 

needs to be submitted to reflect the recommended tolerances. A summary of tolerance 

recommendations is presented in Table 16. Refer to Appendix I for tolerance calculations. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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The submitted wheat and barley data to change the PHI of forage and hay from 14-30 days to 7-

days; and replace the 45-day PHI with growth stage restriction for grain and straw is acceptable. 

The existing wheat tolerances were established using the Abound® Flowable Fungicide with up 

to two foliar applications at 0.20 lb ai/A/application for a total seasonal application rate of 0.40 

lb ai/A. The current tolerances on barley were established based on translation of residue data 

from wheat. The submitted crop field trials on barley and wheat were conducted with the Quilt 

Xcel® with lower application rates (0.13 lb ai/A/application for a total seasonal application rate 

of 0.26 lb ai/A). The application rates used in the field trials are lower than the rates of the 

Abound® label. Therefore, the residue levels were adjusted using the proportionality principle 

to reflect the proposed application rates before deriving a tolerance level. 

The OECD statistical calculation procedures recommend individual tolerances of 10, 15, and 3 

ppm for barley hay, straw, and grain, respectively. The recommended tolerances for wheat 

forage, straw, hay, and grain are 15, 10, 30, 0.15 ppm based on the submitted data. A revised 

Section F needs to be submitted to reflect the recommended tolerances. The petitioner needs to 

submit a revised section F to revise the established tolerance on wheat grain to 0.15 ppm. A 

summary of tolerance recommendations is presented in Table 16. Refer to Appendix I for 

tolerance calculations. 

The data from the wheat processing study indicate that residues of azoxystrobin concentrate in 

aspirated grain fractions (218x), bran (1.4x), and germ (1.2x), but not in flour, middlings, and 

shorts (0.3x, 0.4x, 0.5x, respectively) following processing of the RAC (wheat grain) with 

quantifiable residues. 

Based on the HAFT for wheat grain 0.133 ppm (see Table 13) and concentration factor of 218x 

for aspirated grain fractions, the maximum expected residues would be 29 ppm. The proposed 

tolerance of 460 ppm for aspirated grain fractions is not appropriate since the established 

tolerance on grain aspirated fractions at 420 ppm is adequate. The maximum expected residue in 

wheat bran is 0.19 ppm (1.4x x 0.133 = 0.19). The established tolerance of wheat bran (0.20 

ppm) needs to be removed from the 40 CFR with establishment of wheat grain tolerance at 0.2 

ppm. Based on the HAFT for wheat grain of 0.133 ppm and the 1.2x concentration factor for 

germ, expected residues in wheat germ would be 0.16 ppm, which is close to the recommended 

tolerance for wheat grain of 0.2 ppm; therefore, a tolerance for wheat germ is not needed. 

The processing factors calculated for wheat were less than the maximum theoretical 

concentration factors for wheat of 7.7x for bran, 1.4x for flour, and 8.3x for shorts (based on 

separation into components; OCSPP 860.1520, Table 3). 

Adequate field rotational crop data are available to support the existing rotational crop 

restrictions on the proposed labels. Subsequent to the establishment of tolerances in/on oat and 

rye, rotational crop restrictions on oat and rye should be removed. HED assumes that the 

rotational crop restrictions specified on the Quilt labels are due to use of propioconazole. 

The residue definitions for plants and livestock are not harmonized with Codex; the US and the 

Canadian residue definitions include both the predominant E isomer and the minor Z isomer 

whereas the Codex includes only the E isomer. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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Codex maximum residue limits (MRLs) are established for azoxystrobin on ginseng at 0.1 ppm 

and dry ginseng including red ginseng at 0.5 ppm. A proposed MRL ginseng, processed 

products at 0.5 ppm has been returned to JMPR for further consideration of the processing study. 

Canadian MRLs have been established for residues of azoxystrobin including the (Z)-isomer on 

ginseng roots at 0.5 ppm and at 0.03 ppm for barley, oats, rye, and wheat which are not in 

agreement with the US tolerances, except for ginseng roots. Mexico adopts US tolerances and/or 

Codex MRLs for its export purposes. The Codex MRLs on barley grain and wheat grain are 

estimated at 0.5 and 0.2 ppm, respectively and MRLs for oats and rye are extrapolated from the 

data on barley and wheat, respectively. The US tolerances on oat grain (1.5 ppm) and barley 

grain (3 ppm) could not be harmonized since the Codex MRLs are lower. Setting the US 

tolerance to be consistent with the Codex MRLs might lead to residues in excess of the tolerance, 

despite legal use of the pesticide in accordance with the registered label. 

HED recommends increasing the US tolerances of ginseng to 0.5 ppm, and rye grain and wheat 

grain to 0.2 ppm to harmonize with the numerical portion of the Codex MRL. The US is not 

establishing a tolerance on ginseng (fresh roots) since the dried ginseng covers the fresh roots. 

Analytical reference standards for azoxystrobin and its Z-isomer are currently available at the 

EPA National Pesticide Standards Repository. 

Regulatory Recommendations and Residue Chemistry Deficiencies

HED has examined the residue chemistry database for azoxystrobin. Pending submission of a 

revised Section F (see requirements below), there are no residue chemistry issues that would 

preclude granting tolerances for combined residues of azoxystrobin and the Z-isomer in/on the 

following commodities as follows: 

Ginseng................................................................0.50 ppm 

Oat, forage..............................................................5.0 ppm 

Oat, hay ..............................................................10.0 ppm 

Oat, straw .............................................................3.0 ppm 

Oat, grain ............................................................1.50 ppm 

Rye, forage ............................................................7.0 ppm 

Rye, straw ............................................................1.50 ppm 

Rye, grain ............................................................0.20 ppm 

Barley, hay ..........................................................10.0 ppm 

Barley, straw ........................................................15.0 ppm 

Barley, grain ..........................................................3.0 ppm 

Wheat, forage .......................................................15.0 ppm 

Wheat, straw .........................................................10.0 ppm 

Wheat, hay...........................................................30.0 ppm 

Wheat, grain..........................................................0.20 ppm 

Grain, aspirated grain fractions ....................................420 ppm 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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New poultry tolerances and increase of ruminant tolerances are not needed since the addition of 

oat and rye and increase of tolerances in/on barley and wheat does not alter the dietary burdens 

to livestock. 

A human health risk assessment is forthcoming. 

860.1550 Proposed Tolerances

 A revised Section F must be submitted reflecting the recommended tolerances listed in 

Table 16. 

 A revised Section F must be submitted to revise the established tolerance on wheat grain 

to 0.20 ppm. 

Note to PM: In conjunction with establishment of wheat grain tolerance at 0.2 ppm, the 

existing tolerance on wheat bran need to be removed from 40 CFR §180.507(a)(1). 

The e-CFR includes the Z-isomer in the tolerance expression for livestock. The Z-isomer 

should be removed from the tolerance expression for livestock. 

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 (2E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-

methoxyacrylate 

CAS name methyl (αE)-2-[[6-(2-cyanophenoxy)-4-pyrimidinyl]oxy]-α-(methoxymethylene)-

benzeneacetate 

CAS registry number 131860-33-8 

End-use products (EP) 20% SC formulation (Azoxystrobin SC; Ortiva); Abound® Flowable Fungicide 

(EPA Reg. No. 100-1098), Quilt® Fungicide (EPA Reg. No. 100-1178), and 

Quilt Xcel® Fungicide (EPA Reg. No. 100-1324) 

N N

O O

CN OCH3

O

H3CO
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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Table 1. Azoxystrobin Nomenclature.

Regulated metabolite, Zisomer 

Common name Azoxystrobin, Z-isomer 

Company experimental name R230310 

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 P = 2.5 

UV/visible absorption spectrum Not available 

860.1200 Directions for Use

In support of the proposed import tolerance, Syngenta has submitted a draft label with English 

translations for the 20% SC formulation of azoxystrobin (Azoxystrobin SC; Ortiva) reflecting 

established use patterns in Korea. A summary of the proposed use patterns for ginseng is 

presented in Table 3. 

Syngenta has submitted proposed use directions (Section B) for the Abound Flowable Fungicide, 

EPA Reg. No. 100-1098; Quilt Fungicide, EPA Reg. No. 100-1178; and Quilt Xcel Fungicide, 

EPA Reg. No. 100-1178 on oats, rye, barley, and wheat. A summary of proposed azoxystrobin 

N N

O O

CN

O OCH3

H3CO
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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end-use products is presented in Table 4. The proposed use directions for oats, rye, barley, and 

wheat are presented in Table 5. 

Table 3. Summary of Directions for Use of Azoxystrobin on Ginseng. 

Applic. Timing; 

Type; and Equip.

Formulation Applic. 

Rate1 

Max. No. 

Applic. per 

Season 

Max. Seasonal 

Applic. Rate 

PHI 

(days) 

Use Directions and 

Limitations

Ginseng 

Foliar; 

Broadcast; 

Equipment not 

specified 

20% SC 10 mL 

formulated 

product/ 

20 L water

4 Not specified: 

Run-off 

spraying is 

recommended

7 Applications are to be made 

at the beginning of 

infestation after leaves are 

fully opened with a 10-day 

retreatment interval (RTI). 

Use of surfactants or 

penetration stimulators is 

prohibited. 

Table 4. Summary of Proposed Azoxystrobin End-Use Products. 

Trade Name Reg. No. % ai of 

formulation 

Formulation 

Type 

Target Crop Source 

Abound® 

Flowable 

Fungicide 

100-1098 22.9% ai 

(2.08 lb ai/gal) 

SC Cereals (wheat, 

triticale, barley, 

oats, and rye) 

Undated supplemental label 

included in Section B 

Quilt ® 

Fungicide 

100-1178 7% azoxystrobin 

(0.62 lb ai/gal) 

11.7% 

propiconazole 

(1.04 lb ai/gal) 

SE Cereals (wheat, 

triticale, barley, 

oats, and rye) 

Undated supplemental label 

included in Section B 

Quilt Xcel® 

Fungicide 

100-1324 13.5% 

azoxystrobin 

(1.18 lb ai/gal) 

11.7% 

propiconazole 

(1.02 lb ai/gal) 

SE Cereals (wheat, 

triticale, barley, 

oats, and rye) 

Undated supplemental label 

included in Section B 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 12 of 58 

Table 5. Summary of Directions for Use of Azoxystrobin. 

Applic. Timing, 

Type, and Equip. 

Formulation 

[EPA Reg. 

No.] 

Applic. Rate

fl oz/A 

(lb ai/A) 

Max. 

No. 

Applic. 

per 

Season

Max. 

Seasonal 

Applic. 

Rate 

fl oz/A 

(lb ai/A)

PHI 

(days) Use Directions and Limitations

Cereals (Wheat, Triticale) 

Foliar 

Ground, aerial or 

chemigation 

2.08 lb 

ai/gal SC 

[100-1098] 

4.0-12 

(0.07-0.20) 21 0.40 

7-forage, 

hay 

 

Applications are to be made prior 

to disease development. 

Do not apply after Feekes 10.54. 

Do not apply more than 0.40 lb 

ai/A/season of azoxystrobincontaining products. 

A crop oil concentrate adjuvant 

may be added at 1.0% v/v to 

optimize efficacy. 

Foliar 

Ground, aerial or 

chemigation 

SE/MAI 

(0.62 lb 

ai/gal) 

[100-1178] 

7-14 

(0.03-0.07) 21 28 

(0.14) 

7-forage, 

hay 

 

Apply Quilt in the spring for 

suppression of early season 

diseases. Follow up with a 

second application for full season 

control. For high yields apply 

Quilt when flag leaf is 50% to 

full head emergence (Feekes 

10.5). 

Applications may be made no 

closer than a 14-day interval. 

Do not apply after Feekes 10.54. 

Do not apply more than 0.40 lb 

ai/A/season of azoxystrobincontaining products. 

Foliar 

Ground, aerial or 

chemigation 

SE/MAI 

(1.18 lb 

ai/gal) 

[100-1324] 

7-14 

(0.06-0.13) 21 28 

(0.26) 

7-forage, 

hay 

 

Apply Quilt in the spring for 

suppression of early season 

diseases. Follow up with a 

second application for full season 

control. For high yields apply 

Quilt when flag leaf is 50% to 

full head emergence (Feekes 

10.5). 

Applications may be made no 

closer than a 14-day interval. 

Do not apply after Feekes 10.54. 

Do not apply more than 0.40 lb 

ai/A/season of azoxystrobincontaining products. 

Cereals (Barley, Oat and Rye) 100-1178, 100-1324 includes Triticale

Foliar 

Ground, aerial or 

chemigation 

2.08 lb 

ai/gal SC 

[100-1098] 

6-12 

(0.10-0.20) 21 0.40 

7-forage, 

hay 

 

Applications are to be made prior 

to disease development. 

 Do not apply after Feekes 10.54. 

Minimum volume for aerial 

applications is 5 gal/A. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 13 of 58 

Table 5. Summary of Directions for Use of Azoxystrobin. 

Applic. Timing, 

Type, and Equip. 

Formulation 

[EPA Reg. 

No.] 

Applic. Rate

fl oz/A 

(lb ai/A) 

Max. 

No. 

Applic. 

per 

Season

Max. 

Seasonal 

Applic. 

Rate 

fl oz/A 

(lb ai/A)

PHI 

(days) Use Directions and Limitations

Foliar 

Ground, aerial or 

chemigation 

SE/MAI 

(0.62 lb 

ai/gal) 

[100-1178] 

7-14 

(0.03-0.07) 21 28 

(0.14) 

7-forage,

hay 

 

Apply Quilt in the spring for 

suppression of early season 

diseases. Follow up with a 

second application for full season 

control. For high yields apply 

Quilt when flag leaf is 50% to 

full head emergence (Feekes 

10.5). 

Applications may be made no 

closer than a 14-day interval. 

Do not apply after Feekes 10.54. 

Do not apply more than 0.40 lb 

ai/A/season of azoxystrobincontaining products. An 

adjuvant may be added at 

recommended rates. 

Foliar 

Ground, aerial or 

chemigation 

SE/MAI 

(1.18 lb 

ai/gal) 

[100-1324] 

7-14 

(0.06-0.13) 21 28 

(0.26) 

7-forage, 

hay 

 

Apply Quilt in the spring for 

suppression of early season 

diseases. Follow up with a 

second application for full season 

control. For high yields apply 

Quilt when flag leaf is 50% to 

full head emergence (Feekes 

10.5). 

Applications may be made no 

closer than a 14-day interval. 

Do not apply after Feekes 10.54. 

Do not apply more than 0.40 lb 

ai/A/season of azoxystrobincontaining products. 1 For resistance management, no more than two sequential 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). Do not make more than two foliar applications of Abound® Flowable Fungicide or other Group 11 

fungicide per season. 

2 For resistance management, the supplemental labels for Quilt® Fungicide and Quilt Xcel® Fungicide do not 

specify the maximum number of applications but the most recent accepted labels for both products dated 3/16/10 

indicates that resistance management guidelines should be followed.

Additional information was received: azoxystrobin content changed from 20% to 21.7%; 

application spray volume (3500 L/ha); product rate (1750 g (ml)/ha); and single application rate 

(379.75 g/ha) (email communication Erin Malone, 10/09/12). Based on these information, the 

maximum seasonal application rate is 1519 g ai/ha (1.36 lb ai/A). 

The proposed supplemental labels/Section B for the Abound® Flowable Fungicide, EPA Reg. 

No. 100-1098; Quilt® Fungicide, EPA Reg. No. 100-1178; and Quilt Xcel® Fungicide, EPA 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 14 of 58 

Reg. No. 100-1324 specify that all applicable directions, restrictions, and precautions on the 

EPA-registered label are to be followed and do not include rotational crop restrictions. 

The most recent accepted labels for Abound® Flowable Fungicide (EPA Reg. No. 100-1098, 

main label dated 8/10/12) and Quilt® Fungicide (EPA Reg. No. 100-1178) and Quilt Xcel® 

Fungicide (EPA Reg. No. 100-1324), main label dated 3/16/10 specify that the product should be 

integrated into an overall disease and pest management strategy. 

For the Abound® Flowable Fungicide, the following plantback intervals (PBIs) have been 

established: 12 months for buckwheat, millet, oats, and rye; and 0 days for all other crops with 

azoxystrobin registered uses. 

For Quilt Xcel® Fungicide (EPA Reg. No. 100-1324), the following PBIs have been established: 

12 months for buckwheat, millet, oats, and rye; 75 days for alfalfa (if propiconazole rate does not 

exceed 0.22 lb ai/A/season); 0 days for bulb crops, carrots, cereals (wheat, barley, triticale), 

celery (and other leaf petiole crops in subgroup 4B), corn (field, seed, popcorn, and sweet), 

grasses grown for seed, mint, peanuts, rice, soybeans, strawberries, sorghum, sugar beets, and 

wild rice; and 105 days for all other crops intended for food/feed. For Quilt® Fungicide (EPA 

Reg. No. 100-1178), the following PBIs have been established: 45 days for oats, rye, and rice; 

105 days for all other crops intended for food/feed. Soybeans may be planted as a double crop 

following a cereal crop which has been treated with Quilt. Do not use hay, forage, and fodder 

from the soybean crop as an animal feed or bedding. 

The registered labels for Quilt and Quilt Xcel recommend a minimum spray volume of 10 gal/A 

(non-trees) and 50 gal/A (tree crops) for ground equipment and minimum of 2 gal/A (non-trees) 

and 10 gal/A (trees) for aerial equipment. The label states that chemigation applications are to 

be made through sprinkler-type irrigation systems only. 

Conclusions: For ginseng, the label directions are adequate to allow evaluation of the residue 

data relative to the proposed use. 

The label directions are adequate to allow evaluation of the residue data relative to the proposed 

uses for certain cereal grains. The submitted field trial data for oats and rye reflect the maximum 

proposed use rates, the minimum RTIs, and the proposed PHIs for the Quilt and Quilt Xcel. 

The submitted crop field trial data on oats, rye, barley, and wheat does not reflect the proposed 

use pattern of the Abound. The crop field trials were conducted using the Quilt Xcel with lower 

application rates than the Abound; residues were adjusted using the proportionality principle. 

Subsequent to the establishment of tolerances in/on oat and rye, the rotational crop restrictions 

on the registered labels for the Abound, Quilt and Quilt Xcel Fungicides should be revised to 

remove the PBIs for oats and rye to 0-days. HED assumes that the rotational crop restrictions 

specified on the Quilt labels are due to use of propioconazole. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 15 of 58 

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 the Analytical Chemtistry Branch (ACB)/Biological and 

Economic Analysis Division (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 LOQ is 0.01 ppm for 

each analyte in crop commodities. 

Data-collection methods

Samples from the submitted ginseng residue studies were analyzed for residues of azoxystrobin 

using gas liquid chromatography/electron capture detection (GLC/ECD); the method number 

was not reported. In MRIDs 48601201 and 48601202, the reported (LOQs; (determined as the 

LLMV) were 0.003 ppm for fresh ginseng and 0.007 ppm for all other commodities. In MRID 

48601203, the LOQs (determined as the LLMV) were 0.02 ppm for fresh ginseng and 0.04 ppm 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 16 of 58 

for all other commodities. The method was adequate for data collection based on acceptable 

concurrent method recoveries, and the fortification levels used in concurrent method recovery 

were adequate to bracket expected residues. 

Samples were extracted twice by blending with acetonitrile (ACN) or acetone and filtered. The 

combined filtrate was partitioned twice with dichloromethane. The dichloromethane extracts 

were evaporated to dryness, reconstituted in n-hexane:dichloromethane (8:2, v:v) or n-hexane, 

and purified by Florisil chromatography. Residues were eluted with dichloromethane/ACN 

(50:50, v:v) or dichloromethane:ethyl acetate (90:10, v:v), evaporated to dryness, reconstituted in 

acetone, and analyzed using GLC/ECD. 

Samples of oats, rye, wheat, and barley commodities from the submitted crop field trials and 

processing studies (wheat only) were analyzed for residues of azoxystrobin and its Z-isomer 

using an acceptable UPLC/MS/MS method, Method RAM 305/03. The method was adequately 

validated in conjunction with the analysis of the field trial and processing study samples. The 

LOQ (determined as the LLMV) was 0.01 ppm for each analyte; the limit of detection (LOD) 

was not reported. 

Briefly, samples were extracted twice with ACN:water (90:10, v:v). After centrifugation, the 

combined extracts were cleaned up on a C18 solid phase extraction column. Residues were 

eluted with ethyl acetate:dichloromethane (55:45, v:v). The eluate was evaporated to dryness 

and re-dissolved in ACN:water (50:50, v:v) for analysis by UPLC/MS/MS. 

Conclusions: An adequate residue analytical method is available for tolerance enforcement in 

crop commodities. The GLC/ECD method used for determination of azoxystrobin in ginseng 

(fresh and dried root) and its processed commodities and the UPLC/MS/MS method, Method 

RAM 305/03, used for determination of azoxystrobin in oats, rye, wheat, and barley 

commodities including wheat processed commodities were 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. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 17 of 58 

860.1380 Storage Stability

DER References:

48601201.der (including MRID 4860102) 

48601203.der 

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 2 years in/on apple, banana, carrot, cucumber, 

grape, leaf lettuce, rape seed, peach, winter wheat straw, wheat forage, and wine. Over the 2-

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 1 year, and in soybean meal, corn grits, 

and orange oil, juice and pulp for at least two years. 

Storage stability studies were conducted to support the MOR studies. Control samples of each 

commodity were fortified with azoxystrobin and placed in storage under the same frozen 

conditions as the treated samples for the same storage durations; no 0-day data were provided. 

The storage conditions and durations for samples collected from the MOR studies submitted are 

presented below in Tables 6 and 7. 

Table 6. Summary of Storage Conditions and Durations of Ginseng Samples from MOR studies.

Matrix Analyte 

Storage 

Temperature 

(°C) 

Actual Storage 

Duration 

Interval of 

Demonstrated 

Storage Stability1 

Ginseng, fresh root Azoxystrobin -20 8-169 days (0.3-5.6 months) Up to 169 days 

Dried ginseng 10-171 days (0.3-5.6 months) Up to 171 days 

Red ginseng 6-174 days (0.2-5.7 months) Up to 174 days 

Dried ginseng extract 

(EtOH) 

11-93 days (0.4-3.1 months) Up to 93 days 

Dried ginseng extract 

(Water) 

4-93 days (0.1-3.1 months) 

Red ginseng extract (EtOH) 4-91 days (0.1-3.0 months) Up to 91 days 

Red ginseng extract (Water) 5-87 days (0.2-2.9 months) Up to 87 days 

1

 Based on storage stability data. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 18 of 58 

Table 7. Summary of Storage Conditions.

Matrix Analyte Storage Temperature 

(°C) 

Actual Storage Duration1,2 Interval of Demonstrated Storage 

Stability3

Magnitude of the Residue Studies 

Rye, 

forage 

Azoxystrobin Frozen at field sites; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

59-113 days (1.9-3.7 months) Residues of azoxystrobin and 

R230310 are stable at <-15 C for at 

least two years in/on corn grits, grain 

sorghum forage, wheat grain stored 

frozen. 

R230310 54-112 days (1.8-3.7 months) 

Rye, 

grain 

Azoxystrobin 31-61 days (1.0-2.0 months) 

R230310 32-62 days (1.1-2.0 months) 

Rye, 

straw 

Azoxystrobin 28-62 days (0.9-2.0 months) 

R230310 27-61 days (0.9-2.0 months) 

Oat, 

forage 

Azoxystrobin Frozen at field sites; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

97-407 days (3.2-13.4 months) Residues of azoxystrobin and 

R230310 are stable at <-15 C for at 

least two years in/on soybean meal, 

corn grits, carrot root, leaf lettuce, 

grain sorghum forage, orange oil, and 

orange juice; and residues of 

azoxystrobin and R230310 are stable 

for up to 2 years in cucumbers, 

apples, grapes, peaches, peanuts, 

pecans, rapeseed, tomatoes, bananas, 

and wheat grain stored frozen. 

R230310 97-403 days (3.2-13.3 months) 

Oat, hay Azoxystrobin 92-447 days (3.0-14.7 months) 

R230310 92-445 days (3.0-14.6 months) 

Oat, grain Azoxystrobin 37-359 days (1.2-11.8 months) 

R230310 37-359 days (1.2-11.8 months) 

Oat, Oat, 

straw 

Azoxystrobin 51-373 days (1.7-12.3 months) 

R230310 50-372 days (1.6-12.2 months) 

Barley, 

hay 

Azoxystrobin Frozen at field sites; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

64-469 days (2.1-15.4 months) 

R230310 63-468 days (2.1-15.4 months) 

Barley, 

grain 

Azoxystrobin 45-412 days (1.5-13.6 months) 

R230310 45-412 days (1.5-13.6 months) 

Barley, 

hay 

Azoxystrobin Frozen at field sites; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

64-469 days (2.1-15.4 months) 

R230310 63-468 days (2.1-15.4 months) 

Barley, 

grain 

Azoxystrobin 45-412 days (1.5-13.6 months) 

R230310 45-412 days (1.5-13.6 months) 

Barley, 

straw 

Azoxystrobin 46-399 days (1.5-13.1 months) 

R230310 45-399 days (1.5-13.1 months) 

Wheat, 

forage 

Azoxystrobin Frozen at field sites; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

53-392 days (1.7-12.9 months) 

R230310 52-391 days (1.7-12.9 months) 

Wheat, 

hay 

Azoxystrobin 76-404 days (2.5-13.3 months) 

R230310 75-403 days (2.5-13.3 months) 

Wheat, 

grain 

Azoxystrobin 40-452 days (1.3-14.9 months) 

R230310 40-452 days (1.3-14.9 months) 

Wheat, 

straw 

Azoxystrobin 42-455 days (1.4-15.0 months) 

R230310 41-454 days (1.3-14.9 months) 

Wheat Processing Study

Wheat, 

grain 

(processin

g study) 

Azoxystrobin Ambient at field sites; 

10 °F at processor; 

-10 at preparation 

facility; 

-20 at analytical 

laboratory 

181-447 days (6.0-14.7 months) Residues of azoxystrobin and 

R230310 are stable at <-15 C for at 

least two years in/on soybean meal, 

corn grits, carrot root, leaf lettuce, 

grain sorghum forage, orange oil, and 

orange juice; and residues of 

azoxystrobin and R230310 are stable 

for up to 2 years in cucumbers, 

apples, grapes, peaches, peanuts, 

pecans, rapeseed, tomatoes, bananas, 

and wheat grain stored frozen. 

R230310 

Wheat, 

AGF 

Azoxystrobin 55-62 days (1.8-2.0 months) 

R230310 

Wheat, 

bran 

Azoxystrobin 49-56 days (1.6-1.8 months) 

R230310 42-49 days (1.4-1.6 months) 

Wheat, 

flour 

Azoxystrobin 43-50 days (1.4-1.6 months) 

R230310 

Wheat, 

middlings 

Azoxystrobin 48-55 days (1.6-1.8 months) 

R230310 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 19 of 58 

Table 7. Summary of Storage Conditions.

Matrix Analyte Storage Temperature 

(°C) 

Actual Storage Duration1,2 Interval of Demonstrated Storage 

Stability3

Wheat, 

shorts 

Azoxystrobin 49-56 days (1.6-1.8 months) 

R230310 

Wheat, 

germ 

Azoxystrobin 43-50 days (1.4-1.6 months) 

R230310 1 Interval from harvest to analysis; Extracts were stored 0-6 days prior to analysis. 2

 Interval from harvest/processing to analysis. Extracts were stored 0-1 days prior to analysis. Samples were processed within

398 days of harvest. 

3 DP# 390152, 1/4/12, M. Negussie 

Conclusions: The available storage stability data for azoxystrobin on representative crops are 

adequate to support the storage durations and conditions of samples of oats, rye, wheat, barley, 

and ginseng raw agricultural commodities and wheat processed commodities from the submitted 

crop field trials. 

 

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 

PP#8E7474; DP#s 362963 and 363046, 8/20/09, M. Negussie 

PP#1E7851; DP# 390152, 01/04/12, M. Negussie 

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. 

Previously, the maximum theoretical dietary burdens (MTDBs) of azoxystrobin were estimated 

to be 51.3 ppm (beef), 44.4 ppm (dairy cattle), 14.4 ppm (poultry), and 15 ppm (swine). 

(DP# 390152, M. Negussie, 01/04/12). There are established tolerances for numerous livestock 

feedstuffs. The additional livestock feedstuffs associated with this petition are grain, forage, hay, 

and straw of oats and rye. The established tolerances for hay and straw of wheat and hay of 

barley will increase based on the submitted data, but were not included in the current dietary 

burden estimate since those tolerances will not affect the total estimated dietary burden. The 

proposed commodities are fed to beef and dairy cattle, but are not fed to poultry or swine, except 

oat and rye grain which are fed to poultry. The previously estimated dietary burden will not be 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 20 of 58 

affected since the recommended tolerances and the percents of the diets are much lower for oat 

and rye commodities. 

Table 8. 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 35 11 4.5 

Processed potato waste CC 15 10 8 5.3 

Canola meal PC 88 10 1.0 0.114 

TOTAL BURDEN -- -- 100 -- 44.4 

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 in pastures. 

3) Canola and cottonseed meals are listed in diets, but could be replaced 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. 

A poultry feeding study conducted at 60 ppm yielded no quantifiable azoxystrobin residues in 

eggs or tissues. This represents a 4X exaggeration of the calculated dietary burden for poultry. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 21 of 58 

Conclusions. The addition of oats and rye and the increase of tolerances for some barley and 

wheat commodities do not alter the dietary burdens of azoxystrobin to ruminants, and the 

existing tolerances for ruminant commodities will not be exceeded with the proposed uses on 

oats and rye. 

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 40 CFR §180.6(a)]. No tolerances are needed for poultry tissues or 

eggs. 

860.1500 Crop Field Trials 

Ginseng

DER References: 48601201.der.doc (includes review of MRID 4860102) 

 48601203.der.doc (2008 trials) 

DP# 225494, 5/1/96, B. Schneider 

Syngenta has submitted residue data for azoxystrobin on ginseng. Two trials were conducted in 

Korea during the 2008 growing season (MRID 48601203), and two consecutive-year trials (2009 

and 2010) were conducted in Korea during the 2009-2010 growing seasons (MRIDs 48601201 

and 48601202). The results from these trials are discussed below, and the residue data for dried 

ginseng are summarized in Table 9 (refer to the DERs for residue data for fresh ginseng, red 

ginseng, and ginseng extracts). 

Table 9. Summary of Residue Data from Ginseng Crop Field Trials with Azoxystrobin.

Commodity Plot1 Total App. 

Rate 

lb ai/A 

(g ai/ha) 

PHI Residue Levels (ppm)2

n Sample 

Min. 

Sample 

Max. 

LAFT3 HAFT3 Median Mean Std. 

Dev. 

Ginseng (proposed use = 10 mL formulated product/20 L water, 7-day PHI)

MRID 48601203 

Ginseng, 

dried root 

2008 trials 1.98 

(2,222) 

7 2 0.10 0.14 0.12 0.13 0.13 0.13 N/A 

MRIDs 48601201 and 48601202 

Ginseng, 

dried root 

1a 

(2009 trials) 

1.21-1.29 

(1,355-1,450) 

7 2 0.034 0.049 0.034 0.048 0.041 0.041 N/A 

1b 

(2009-2010 

trials) 

2.43-2.58 

(2,724-2,894) 

7 2 0.060 0.179 0.063 0.177 0.120 0.120 N/A 

1

 The 2008 trials and Plot 1a received four foliar applications in year 1; plot 1b received four additional foliar 

applications in year 2 according to the same use pattern. The total seasonal application rate for Plot 2b was 1.221-

1.288 lb ai/A (1,369-1,444 g ai/ha). 

2

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. N/A = Not applicable. 3

 LAFT = lowest average field trial; HAFT = highest average field trial. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 22 of 58 

MRID 48601203 (2008 trials)

Syngenta has submitted field trial data for azoxystrobin on ginseng. Two ginseng field trials 

were conducted in the Republic of Korea in the Gangwon and Gyunggi provinces during the 

2008 growing season. 

Each trial consisted of one untreated plot and one treated plot of 6-year-old ginseng. Each 

treated plot received four foliar applications of a 20% SC formulation of azoxystrobin 

(Azoxystrobin SC; Ortiva) at a rate of 0.496 lb ai/A/application (556 g ai/ha/application), for a 

total seasonal rate of 1.983 lb ai/A (2,222 g ai/ha). Applications were made at 10-day 

retreatment interval (RTIs) using ground equipment in spray volumes of 594 gal/A (5,556 L/ha). 

Adjuvants were not added to the spray mixture for any of the applications. Samples of ginseng 

root were harvested from all trials at a 7-day PHI. The harvested fresh root was divided into 

three portions, with one sample reserved for analysis of fresh root, and the remaining two 

samples reserved for production of dried ginseng and red ginseng

Samples were analyzed for residues of azoxystrobin using an adequately validated GLC/ECD 

method. The reported LOQs (determined as the LLMV) were 0.02 ppm for fresh ginseng root 

and 0.04 ppm for dried ginseng, red ginseng, and the dried/red ginseng extracts. Adequate 

storage stability data are available to support sample storage intervals and conditions. Refer to 

Table 6 for sample storage conditions and durations. 

The field trial results for dried ginseng are presented in Table 9 (refer to the DERs for residue 

data for fresh ginseng, red ginseng, and ginseng extracts). Following four foliar applications of 

the 20% SC formulation of azoxystrobin at a total rate of 1.983 lb ai/A (2,222 g ai/ha), residues 

(and per trial averages) of azoxystrobin were 0.10-0.14 (0.12-0.13) ppm in dried ginseng 

harvested at a 7-day PHI. 

Residue decline data were not submitted; however, none are required because ginseng needs 

three or fewer total trials. 

MRIDs 48601201 and 48601202 (2009 and 2010 trials)

Syngenta has submitted field trial data for azoxystrobin on ginseng. Two consecutive-year field 

trials were conducted in the Republic of Korea in the Chungbuk and Chungnam provinces during 

the 2009-2010 growing seasons. 

Each trial consisted of one untreated plot and one treated plot of 4-year-old ginseng. The treated 

plot was subdivided into plot 1a and plot 1b. Each subplot received four foliar applications of a 

20% SC formulation of azoxystrobin (Azoxystrobin SC; Ortiva) at a rate of 0.300-0.327 lb 

ai/A/application (336-366 g ai/ha/application), for a total seasonal rate of 1.209-1.294 lb ai/A 

(1,355-1,450 g ai/ha). Applications were made at 10-day RTIs using ground equipment in spray 

volumes of 359-392 gal/A (3,360-3,666 L/ha). Adjuvants were not added to the spray mixture 

for any of the applications. Samples of ginseng root were harvested from plot 1a at a 7-day PHI. 

Plot 1b received four additional foliar applications in year 2 (305- to 314-day RTI from year 1 

applications) using the same use pattern as the previous year for a total seasonal rate of 1.221-
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 23 of 58 

1.288 lb ai/A (1,369-1,444 g ai/ha). The overall total rate for plot 1b was 2.430-2.582 lb ai/A 

(2,724-2,894 g ai/ha). Samples of ginseng root were harvested from plot 1b at a 7-day PHI. 

Harvested fresh root collected at the 7-day PHI from both subplots was divided into three 

portions, with one sample reserved for analysis of fresh root, and the remaining two samples 

reserved for production of dried ginseng and red ginseng. 

Samples were analyzed for residues of azoxystrobin using an adequately validated GLC/ECD 

method. The reported LOQs (determined as the LLMV) were 0.003 ppm for fresh root and 

0.007 ppm for dried ginseng, red ginseng, and the dried/red ginseng extracts. Adequate storage 

stability data are available to support sample storage intervals and conditions. Refer to Table 6 

for sample storage conditions and durations. 

The field trial results for dried ginseng are presented in Table 9 (refer to the DERs for residue 

data for fresh ginseng, red ginseng, and ginseng extracts). Following four foliar applications 

(year 1) of the 20% SC formulation of azoxystrobin at a total rate of 1.209-1.294 lb ai/A (1,355-

1,450 g ai/ha), residues (and per trial averages) of azoxystrobin were 0.034-0.049 (0.034-0.048) 

ppm in dried ginseng harvested at a 7-day PHI. 

Following four additional applications in year 2 for a total rate of 2.430-2.582 lb ai/A (2,724-

2,894 g ai/ha), residues (and per trial averages) of azoxystrobin were 0.021-0.026 (0.022-0.025) 

ppm in fresh root and 0.060-0.179 (0.063-0.177) ppm in dried ginseng harvested at a 7-day PHI. 

In the Chungbuk trial, there was a proportional (~2x) increase in residues of azoxystrobin in 

fresh ginseng root, dried ginseng, and red ginseng following eight applications over 2 

consecutive years when compared to residues following four applications over 1 year. Residues 

in the dried/red ginseng extracts were 2.7-4.5x higher in the 2-year samples. In the Chungnam 

trial; residues of azoxystrobin were comparable in 1- and 2-year fresh ginseng root (average 

residues of 0.026 and 0.025 ppm, respectively); however, residues in dried ginseng were 3.7x 

higher, and residues in red ginseng increased proportionally (~2x). Residues in the dried ginseng 

extracts were ~2x higher, and residues in the red ginseng extracts were ~5-7x higher. 

Residue decline data were not submitted; however, none are required because ginseng needs 

three or fewer total trials. 

Conclusions: The submitted ginseng crop field trial data are acceptable. The number and 

locations of the field trials are adequate to reflect use in Korea, a major exporter of ginseng to the 

US. The Agency considers the RAC of ginseng to be the dried root, defined as “ginseng” for 

tolerance purposes (refer to DP# 225494). 

The study results indicated that average residues of azoxystrobin were 0.034-0.13 ppm in 

samples of dried ginseng from the 1-year plots (four trials) and 0.063-0.177 ppm in samples from 

the 2-year plots (two trials). Comparison of the 1- and 2-year results in the consecutive-year 

study indicated that residues were ~2-3.7x higher in samples harvested following eight 

applications over 2 consecutive years when compared to residues following four applications 

over 1 year. Because HED believes that consecutive-year harvests are likely to be common 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 24 of 58 

cultural practice for ginseng in Korea, the 2-year data were included in the tolerance calculation 

for ginseng. 

Samples from the submitted studies were not analyzed for residues of the Z-isomer; therefore, 

the petitioner proposed a worst-case metabolic factor of 0.09x, determined from the existing root 

crop data reflecting analysis for residues of azoxystrobin and the Z-isomer. The results of the 

available field trial data on root and tuber vegetables (carrot, radish, sugar beet, and potato DP# 

D260134, M. J. Nelson, 09/06/2000) indicate that residues of the Z-isomer were all below the 

LOQ (0.01 ppm). The proposed factor is adequate to estimate the expected residues. This factor 

was applied to the residue results for dried ginseng for calculation of the recommended tolerance 

level for ginseng. 

The submitted data for ginseng dried root are sufficient for establishing an import tolerance for 

ginseng resulting from use of azoxystrobin in Korea. Based on the submitted data, reflecting 1- 

and 2-year applications and extrapolation of residues of azoxystrobin to account for the Zisomer, the recommended tolerance for ginseng is 0.4 ppm. The tolerance calculations are 

presented in Appendix I. 

Oats

DER Reference: 48681702.der.doc 

Syngenta has submitted field trial data for azoxystrobin on oats. Twelve field trials were 

conducted in the United States during the 2009-2010 growing seasons in the North American 

Free Trade Agreement (NAFTA) Growing Zones 1 (PA; 1 trial), 2 (SC; 1 trial), 5 (ND, MN, and 

IA; 6 trials), 6 (TX; 1 trial), 7 (SD and ND; 2 trials), and 8 (CO; 1 trial). 

Two trial pairs or sets (trials C12-9086 and C12-9087, and trials C13-9083, C13-9088, and C13-

9091) were each conducted by the same principal field investigator (PFI). All trials reflected use 

of different tank mixes for all applications. Trial C13-9091 was conducted in a different NAFTA 

Zone; thus, HED concludes that this trial may be counted as a separate trial for purposes of 

860.1500 data requirements. Careful examination of the field trial records for the remaining trials 

indicates that the only difference between trials C12-9086 and C12-9087 was a >20-mile 

separation between trial locations, and the only differences between trials C12-9083 and C12-

9088 were 5- to 11-day off-set in application dates and a >25% difference in spray volume (~20 

gal/A vs. 2 gal/A). HED has concluded that the differences between trials C12-9086 and C12-

9087 are insufficient to classify them as separate trials; therefore, these trials constitute a single 

trial with replicate samples for purposes of 860.1500 data requirements. Trials C13-9083 and 

C13-9088 would not normally satisfy the ChemSAC criteria for differentiation of field trials; 

however, because of the appreciable differences in spray volumes (~20 vs. ~2 gal/A) and the 

variation in residue results between the two trials, HED concludes that these trials may be 

counted as separate trials. The adjustment in trial numbers results in a total of 11 field trials, 

with five trials conducted in NAFTA Zone 5. 

Each trial consisted of one untreated plot and two treated plots; separate plots were established 

for the harvest of forage and hay and for the harvest of grain and straw. At each trial location, 

the treated plots received two foliar broadcast applications of a multiple active ingredient (MAI) 

suspo-emulsion (SE) formulation (Quilt XcelTM) containing 1.18 lb ai/gal azoxystrobin and 1.02 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 25 of 58 

lb ai/gal propiconazole. Applications were targeted at growth stage 5 (BBCH 30), and 7 days 

prior to harvest for the forage and hay plots, and at 14 days prior to Feekes 10.54 (BBCH 71), 

and Feekes 10.54 for grain and straw plots. BBCH 71 is described as the watery ripe stage, 

where first grains have reached half their finalsize. This stage is prior to the milk stage. Each 

treated plot received two applications of azoxystrobin at 0.1228-0.1366 lb ai/A/application, for a 

total seasonal rate of 0.2494-0.2696 lb ai/A. Applications were made at 11- to 17-day RTIs 

using ground equipment in spray volumes of 1.97-31.39 gal/A. A nonionic surfactant (NIS) was 

added to the spray mixtures for all applications in eleven trials, and a crop oil concentrate (COC) 

was added to the spray mixtures in one trial. Samples of forage and hay were harvested from all 

trials at PHIs of 7 and 14 days; grain and straw were harvested at maturity (PHIs of 25-48 days). 

Additional forage and hay samples were harvested at PHIs of 0, 3, 7, and 21 days from one trial 

(in ND) to assess residue decline; additional grain and straw samples were collected 14 and 7 

days prior to, and 7 days after, maturity. The petitioner noted that no 0-day decline samples were 

collected for hay and that the 3-day samples were actually collected at a 5-day PHI. Hay 

samples were dried to approximately 10-20% moisture content; drying intervals were not 

reported. 

Samples were analyzed for residues of azoxystrobin and its Z-isomer (R230310) using an 

UPLC/MS/MS, Method RAM 305/03. The LOQ determined as the lowest level of method 

validation, LLMV was 0.01 ppm for each analyte. The method was adequate for data collection 

based on acceptable concurrent recovery data. The fortification levels used in concurrent method 

recovery were adequate to bracket expected residue levels. 

Samples were shipped from the field sites to a sample preparation facility, where they were 

homogenized prior to shipment to the analytical laboratory. Samples were stored frozen (<-10 

°C at the preparation facility and <-20 °C at the analytical laboratory) from collection to analysis 

for 97-407 days (3.2-13.4 months) for forage, 92-447 days (3.0-14.7 months) for hay, 37-359 

days (1.2-11.8 months) for grain, and 50-373 days (1.6-12.3 months) for straw. All samples 

were analyzed within 0-11 days of extraction. Adequate storage stability data are available to 

support the sample storage durations and conditions of samples from the submitted field trials. 

Following two foliar broadcast applications of the 1.18 lb ai/gal SE formulation of azoxystrobin 

at 0.2494-0.2650 lb ai/A, residues of azoxystrobin, R230310, and combined residues (and per 

trial averages), respectively, in/on forage were: 0.106-2.21 (0.109-1.98), <0.01-0.124 (<0.01-

0.112), and <0.116-2.33 (<0.119-2.09) ppm at the 7-day PHI and 0.0417-1.02 (0.0513-0.970), 

<0.01-0.0734 (<0.01-0.0679), and <0.0517-1.09 (<0.0613-1.04) ppm at the 14-day PHI; 

corresponding residues in/on hay were: 0.147-3.38 (0.200-3.16), <0.01-0.220 (<0.0120-0.198), 

and <0.157-3.59 (<0.212-3.36) ppm at the 7-day PHI and 0.126-2.34 (0.139-1.77), <0.01-0.181 

(<0.01-0.123), and <0.136-2.52 (<0.149-1.89) ppm at the 14-day PHI. In/on grain and straw 

harvested at PHIs of 25-48 days following two applications at 0.2532-0.2696 lb ai/A, 

corresponding residues (and per trial averages) were: 0.0115-0.636 (0.0127-0.374), <0.01-0.121 

(<0.01-0.0709), and <0.0215-0.751 (<0.0227-0.444) ppm in/on grain, and 0.0429-0.934 (0.0487-

0.880), <0.01-0.146 (<0.01-0.131), and <0.0529-1.08 (<0.0587-1.01) ppm in/on straw. 

The residue decline results were variable for all crop matrices. The data indicate that combined 

residues of azoxystrobin and R230310 in/on oat forage and hay generally declined through the 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 26 of 58 

14-day PHI but increased at the 21-day PHI. Combined residues in/on oat grain increased from 

the 11- to the 18-day PHI, then decreased at the 25-day target PHI and the 32-day PHI. 

Combined residues in straw decreased from the 11- to the 18-day PHI, were highest at the target 

25-day PHI, and decreased at the 32-day PHI. 

Table 10. Summary of Residue Data from Oat Crop Field Trials with Azoxystrobin.

Commodity Analyte Total App. 

Rate 

(lb ai/A) 

PHI Residue Levels (ppm)1

n Sample 

Min. 

Sample 

Max. 

LAFT2 HAFT2 Median Mean Std. 

Dev. 

Forage Azoxystrobin 0.2494-

0.2650 

7 11 0.106 2.21 0.109 1.98 0.781 0.784 0.566 

R230310 11 <0.01 0.124 <0.01 0.112 0.0312 0.0438 0.0345

Combined 11 <0.116 2.33 <0.119 2.09 0.815 0.826 0.597 

Combined3 11 0.179 3.59 0.183 3.22 1.26 1.27 0.92 

Azoxystrobin 14 11 0.0417 1.02 0.0513 0.970 0.262 0.391 0.314 

R230310 11 <0.01 0.0734 <0.01 0.0679 0.0126 0.0297 0.0249

Combined 11 <0.0517 1.09 <0.0613 1.04 0.272 0.421 0.338 

Hay Azoxystrobin 7 11 0.147 3.38 0.200 3.16 1.06 1.48 1.19 

R230310 11 <0.01 0.220 <0.0120 0.198 0.0577 0.0930 0.0724

Combined 11 <0.157 3.59 <0.212 3.36 1.19 1.58 1.26 

Combined3 11 0.242 5.53 0.326 5.17 1.83 2.43 1.94 

Azoxystrobin 14 11 0.126 2.34 0.139 1.77 0.576 0.718 0.496 

R230310 11 <0.01 0.181 <0.01 0.123 0.0435 0.0567 0.0402

Combined 11 <0.136 2.52 <0.149 1.89 0.619 0.774 0.534 

Grain Azoxystrobin 0.2532-

0.2696 

25-48 11 0.0115 0.636 0.0127 0.374 0.0521 0.120 0.134 

R230310 11 <0.01 0.121 <0.01 0.0709 0.0106 0.0238 0.0229

Combined 11 <0.0215 0.751 <0.0227 0.444 0.0626 0.144 0.157 

Combined3 11 0.033 1.16 0.035 0.684 0.096 0.221 0.241 

Straw Azoxystrobin 25-48 11 0.0429 0.934 0.0487 0.880 0.197 0.387 0.332 

R230310 11 <0.01 0.146 <0.01 0.131 0.0189 0.0457 0.0438

Combined 11 <0.0529 1.08 <0.0587 1.01 0.215 0.432 0.373 

Combined3 11 0.082 1.66 0.129 1.56 0.564 0.721 0.556 1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQ (0.01 ppm) was used for any results reported as <LOQ in Table C.3. N/A = Not applicable. 2

 LAFT = lowest average field trial; HAFT = highest average field trial. 

3

 Adjusted combined residues. 

Rye 

DER Reference: 48681701.der.doc 

Syngenta has submitted field trial data for azoxystrobin on rye. Four field trials were conducted 

in the United States during the 2009 growing season in the NAFTA Growing Zones 2 (SC; 1 

trial), 5 (IA; 1 trial), and 7 (ND and NE; 2 trials). The petitioner indicated that a fifth trial, 

conducted in Zone 5 (IA), was not included in the study because it was conducted with annual 

ryegrass instead of cereal grain rye. 

Each trial consisted of one untreated plot and two treated plots; separate plots were established 

for the harvest of forage and for the harvest of grain and straw. At each trial location, the treated 

plots received two foliar broadcast applications of a MAI SE formulation (Quilt XcelTM) 

containing 1.18 lb ai/gal azoxystrobin and 1.02 lb ai/gal propiconazole. Applications were 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 27 of 58 

targeted at Feekes growth stage 5 (BBCH 30), and 7 days prior to harvest for the forage plots, 

and at 14 days prior to Feekes 10.54 (BBCH 71), and Feekes 10.54 (BBCH 71) for grain and 

straw plots. BBCH 71 is described as the watery ripe stage, where first grains have reached half 

their finalsize. This stage is prior to the milk stage. Each treated plot received two applications 

of azoxystrobin at 0.1278-0.1330 lb ai/A/application, for a total seasonal rate of 0.2563-0.2646 lb 

ai/A. Applications were made at 13- to 16-day RTIs using ground equipment in spray volumes 

of 2.01-23.37 gal/A. A NIS was added to the spray mixtures for all applications in three trials, 

and a COC was added to the spray mixtures in one trial. Samples of forage were harvested from 

all trials at PHIs of 6-8 and 13-15 days; grain and straw were harvested at maturity (PHIs of 34-

50 days). Additional forage samples were harvested at PHIs of 0, 3, 7, and 21 days from one 

trial (in IA) to assess residue decline; additional grain and straw samples were collected 14 and 7 

days prior to, and 7 days after, maturity. 

Samples were analyzed for residues of azoxystrobin and its Z-isomer using an UPLC/MS/MS, 

Method RAM 305/03. The LOQ; determined as the LLMV was 0.01 ppm for each analyte. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. 

 

Samples were shipped from the field sites to a sample preparation facility, where they were 

homogenized prior to shipment to the analytical laboratory. Samples were stored frozen (<-10 

°C at the preparation facility and <-20 °C at the analytical laboratory) from collection to analysis 

for 54-113 days (1.8-3.7 months) for forage, 31-62 days (1.0-2.0 months) for grain, and 27-62 

days (0.9-2.0 months) for straw. All samples were analyzed within 0-5 days of extraction. 

Adequate storage stability data are available to support the sample storage durations and 

conditions of samples from the submitted field trials. 

Following two foliar broadcast applications of the 1.18 lb ai/gal SE formulation of azoxystrobin 

at a total rate of 0.2571-0.2617 lb ai/A, residues (and per trial averages) of azoxystrobin, 

R230310, and combined residues, respectively, in/on forage were: 1.03-1.54 (1.05-1.52), 0.0305-

0.0955 (0.0359-0.0955), and 1.06-1.59 (1.08-1.58) ppm at the 6- to 8-day PHI; and 0.396-0.628 

(0.418-0.590), 0.0176-0.0301 (0.0183-0.0299), and 0.414-0.658 (0.437-0.619) ppm at the 13- to 

15-day PHI. In/on grain and straw harvested at PHIs of 34-50 days following two applications at 

0.2563-0.2646 lb ai/A, corresponding residues (and per trial averages) were: <0.01-0.0159 

(<0.01-0.0151), <0.01, and <0.02-<0.0259 (<0.02-<0.0251) ppm in/on grain, and 0.0911-0.495 

(0.0952-0.382), <0.01-0.0363 (<0.01-0.0315), and <0.101-0.531 (<0.105-0.414) ppm in/on 

straw. 

The residue decline data indicate that combined residues of azoxystrobin and R230310 in/on rye 

forage increased from the 0- to the 3-day PHI, and then decreased thereafter. Combined residues 

in/on straw generally decreased with increasing PHI; residues in/on grain were <LOQ at all 

sampling intervals; therefore, residue decline could not be assessed. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 28 of 58 

Table 11. Summary of Residue Data from Rye Crop Field Trials with Azoxystrobin.

Commodity Analyte Total App. 

Rate 

(lb ai/A) 

PHI Residue Levels (ppm)1

n Sample 

Min. 

Sample 

Max. 

LAFT2 HAFT2 Median Mean Std. 

Dev. 

Forage Azoxystrobin 0.2571-

0.2617 

6-8 4 1.03 1.54 1.05 1.52 1.25 1.27 0.227 

R230310 4 0.0305 0.0955 0.0359 0.0955 0.0532 0.0595 0.0257

Combined 4 1.06 1.59 1.08 1.58 1.32 1.32 0.249 

Combined3 4 1.63 2.45 1.66 2.43 2.02 2.04 0.384 

Azoxystrobin 13-15 4 0.396 0.628 0.418 0.590 0.486 0.495 0.0794

R230310 4 0.0176 0.0301 0.0183 0.0299 0.0245 0.0243 0.0063

Combined 4 0.414 0.658 0.437 0.619 0.510 0.519 0.0853

Grain Azoxystrobin 0.2563-

0.2646 

34-50 4 <0.01 0.0159 <0.01 0.0151 0.0100 0.0113 0.0026

R230310 4 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A 

Combined 4 <0.02 <0.0259 <0.02 <0.0251 0.0200 0.0213 0.0026

Combined3 4 0.031 0.040 0.031 0.039 0.031 0.033 0.004 

Straw Azoxystrobin 34-50 4 0.0911 0.495 0.0952 0.382 0.158 0.198 0.126 

R230310 4 <0.01 0.0363 <0.01 0.0315 0.0198 0.0203 0.0091

Combined 4 <0.101 0.531 <0.105 0.414 0.178 0.219 0.135 

Combined3 4 0.156 0.818 0.162 0.638 0.273 0.336 0.208 1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQ (0.01 ppm) was used for any results reported as <LOQ in Table C.3. N/A = Not applicable. 2

 LAFT = lowest average field trial; HAFT = highest average field trial. 

3

 Adjusted combined residues. 

Conclusions. Although the number of field trials is technically inadequate, HED concludes that 

the available data are sufficient to support registration of azoxystrobin on oats and rye because 

the field trials conducted cover all zones requested. The field trials reflect the proposed use 

patterns for Quilt® Fungicide (EPA Reg. No. 100-1178 and Quilt Xcel® Fungicide (EPA Reg. 

No. 100-1324). Samples were analyzed for residues of azoxystrobin and its Z-isomer using 

acceptable methods, and the studies are supported by adequate storage stability data. 

The submitted crop field trial data on oats and rye does not reflect the proposed use pattern of the 

Abound® Flowable Fungicide (EPA Reg. No. 100-1098). The crop field trials were conducted 

using the Quilt Xcel® Fungicide (EPA Reg. No. 100-1324) with two foliar applications at 0.13 

lb ai/A/application for a total seasonal application rate of 0.26 lb ai/A. The Abound can be 

applied up to two foliar applications at 0.20 lb ai/A/application for a total seasonal application 

rate of 0.40 lb ai/A. Therefore, the average residues are adjusted using the proportionality 

principle (average residues are multiplied by 1.54 = 0.40/0.26). 

Based on the available data, the proposed tolerances for oat and rye commodities must be revised 

to reflect the appropriate tolerance levels estimated using the OECD statistical calculation 

procedures. HED recommends tolerances to be established at of 5, 10, 3, and 1.5 ppm for oat 

forage, hay, straw, and grain respectively. The recommended tolerances for rye forage, straw, 

and grain are 7, 1.5, and 0.1, respectively. The proposed tolerances by the petitioner do not 

reflect the proposed highest application rate. A revised Section F needs to be submitted to reflect 

the recommended tolerances. A summary of tolerance recommendations is presented in Table 

16. Refer to Appendix I for the tolerance calculations. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 29 of 58 

Barley 

DER Reference: 48681702.der.doc 

Syngenta has submitted field trial data for azoxystrobin on barley. Nine field trials were 

conducted in the United States during the 2009-2010 growing seasons in the NAFTA Growing 

Zones 2 (VA; 1 trial), 5 (ND and MN; 2 trials), 7 (SD, ND and NE; 3 trials), 9 (CO; 1 trial), 10 

(CA; 1 trial), and 11 (ID; 1 trial). 

Each trial consisted of one untreated plot and two treated plots; separate plots were established 

for the harvest of hay and for the harvest of grain and straw. At each trial location, the treated 

plots received two foliar broadcast applications of a MAI SE formulation (Quilt XcelTM) 

containing 1.18 lb ai/gal azoxystrobin and 1.02 lb ai/gal propiconazole. Applications were 

targeted at Feekes growth stage 5 (BBCH 30), and 7 days prior to harvest for the hay plots, and 

at 14 days prior to Feekes 10.54 (BBCH 71), and Feekes 10.54 for grain and straw plots. Each 

treated plot received two applications of azoxystrobin at 0.1255-0.1341 lb ai/A/application, for a 

total seasonal rate of 0.2532-0.2674 lb ai/A. Applications were made at 12- to 15-day RTIs 

using ground equipment in spray volumes of 1.95-30.75 gal/A. A NIS was added to the spray 

mixtures for all applications in eight trials, and a COC was added to the spray mixtures in one 

trial. Samples of hay were harvested from all trials at PHIs of 7 and 14 days; grain and straw 

samples were harvested at maturity (PHIs of 16-49 days). Additional hay samples were 

harvested at PHIs of 0, 3, 7, and 21 days from one trial (in ND) to assess residue decline; 

additional grain and straw samples were collected 14 and 7 days prior to, and 7 days after, 

maturity. Hay samples were dried to approximately 10-20% moisture content; drying intervals 

were not reported. 

Samples were analyzed for residues of azoxystrobin and its Z-isomer using an UPLC/MS/MS, 

Method RAM 305/03. The LOQ; determined as the LLMV was 0.01 ppm for each analyte. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. 

Samples were shipped from the field sites to a sample preparation facility, where they were 

homogenized prior to shipment to the analytical laboratory. Samples were stored frozen (<-10 

°C at the preparation facility and <-20 °C at the analytical laboratory) from collection to analysis 

for 63-469 days (2.1-15.4 months) for hay, 45-412 days (1.5-13.6 months) for grain, and 45-399 

days (1.5-13.1 months) for straw. All samples were analyzed within 0-1 day of extraction. 

Adequate storage stability data are available to support the storage durations and conditions of 

samples from the submitted field trials. 

Following two foliar broadcast applications of the 1.18 lb ai/gal SE formulation of azoxystrobin 

at 0.2532-0.2674 lb ai/A, residues (and per trial averages) of azoxystrobin, R230310, and 

combined residues, respectively, in/on hay were: 0.448-3.77 (0.451-3.62), 0.0139-0.391 

(0.0181-0.343), and 0.462-4.16 (0.469-3.96) ppm at the 7-day PHI; and 0.145-2.93 (0.150-2.73), 

<0.01-0.342 (<0.0107-0.342), and 0.156-3.27 (0.160-3.07) ppm at the 14-day PHI. In/on grain 

and straw harvested at PHIs of 16-49 days following two applications at 0.2560-0.2649 lb ai/A, 

corresponding residues (and per trial averages) were: <0.01-1.07 (<0.01-0.974), <0.01-0.116 

(<0.01-0.112), and <0.02-1.19 (<0.02-1.09) ppm in/on grain; and 0.0835-3.83 (0.0896-3.49), 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 30 of 58 

<0.01-0.463 (<0.01-0.379), and 0.0945-4.29 (0.101-3.87) ppm in/on straw. 

The residue decline data indicate that combined residues of azoxystrobin and R230310 in/on 

barley hay and straw generally decreased with increasing PHI. Residues in/on grain were near or 

below the LOQ at all sampling intervals; therefore, residue decline could not be assessed. 

Table 12. Summary of Residue Data from Barley Crop Field Trials with Azoxystrobin.

Commodity Analyte Total App. 

Rate 

(lb ai/A) 

PHI Residue Levels (ppm)1

n Sample 

Min. 

Sample 

Max. 

LAFT2 HAF

T2 

Median Mean Std. 

Dev. 

Hay Azoxystrobin 0.2532-

0.2674 

7 9 0.448 3.77 0.451 3.62 0.834 1.49 1.20 

R230310 9 0.0139 0.391 0.0181 0.343 0.0702 0.0976 0.100 

Combined 9 0.462 4.16 0.469 3.96 0.904 1.59 1.28 

Combined3 9 0.711 6.41 0.722 6.10 1.39 2.44 1.98 

Azoxystrobin 14 9 0.145 2.93 0.150 2.73 0.337 0.856 0.878 

R230310 9 <0.01 0.342 <0.0107 0.342 0.0343 0.0713 0.105 

Combined 9 0.156 3.27 0.160 3.07 0.371 0.926 0.973 

Grain Azoxystrobin 0.2560-

0.2649 

16-49 9 <0.01 1.07 <0.01 0.974 0.0366 0.183 0.314 

R230310 9 <0.01 0.116 <0.01 0.112 0.0100 0.0273 0.0341

Combined 9 <0.02 1.19 <0.02 1.09 0.0466 0.210 0.350 

Combined3 9 0.031 1.83 0.031 1.68 0.072 0.323 0.539 

Straw Azoxystrobin 16-49 9 0.0835 3.83 0.0896 3.49 0.356 1.24 1.44 

R230310 9 <0.01 0.463 <0.01 0.379 0.0295 0.131 0.157 

Combined 9 0.0945 4.29 0.101 3.87 0.377 1.37 1.59 

Combined3 9 0.146 6.61 0.156 5.96 0.581 2.11 2.45 

1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQ (0.01 ppm) was used for any results reported as <LOQ in Table C.3. 2

 LAFT = lowest average field trial; HAFT = highest average field trial. 

3

 Adjusted combined residues. 

Wheat

DER Reference: 48681704.der.doc 

Residue chemistry memo DP# 230634, 4/30/1997, L. Kutney (PP# 6F4762)

Syngenta has submitted field trial data for azoxystrobin on wheat. Fifteen field trials were 

conducted in the United States during the 2008-2010 growing seasons in the NAFTA Growing 

Zones 2 (VA; 1 trial), 4 (LA; 1 trial), 5 (ND and IA; 3 trials), 6 (TX; 1 trial), 7 (SD and ND; 4 

trials), 8 (TX and CO; 4 trials), and 11 (ID; 1 trial). 

Three trial pairs or sets (trials C13-9033, C13-9038, and C13-9040, trials C16-9037 and C16-

9039, and trials W39-9042 and W39-9043) were each conducted by the same principal field 

investigator (PFI). All trials reflected use of different tank mixes for all applications. Trial C13-

9033 was conducted in a different NAFTA Zone; thus, HED concludes that this trial may be 

counted as a separate trial for purposes of 860.1500 data requirements. Examination of the field 

trial records indicates that there were sufficient differences in the parameters for each remaining 

pair of trials, including differences in wheat variety, dates of initial application (>30 days; trials 

C13-9038 and C13-9040 and trials C16-9037 and C16-9039 only), adjuvant use (COC vs NIS; 

trials C16-9037 and C16-9039 only), >20-mile separation in trial location (trials W39-9042 and 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 31 of 58 

W39-9043 only), irrigation use (furrow vs none; trials W39-9042 and W39-9043 only), and a 

>25% difference in spray volume (~20 gal/A vs. 2 gal/A; trials C13-9038 and C13-9040 only), 

that each trial constitutes a separate trial for purposes of 860.1500 data requirements. 

Each trial consisted of one untreated plot and two treated plots; separate plots were established 

for the harvest of forage and hay and for the harvest of grain and straw. At each trial location, 

the treated plots received two foliar broadcast applications of a MAI SE formulation (Quilt 

XcelTM) containing 1.18 lb ai/gal azoxystrobin and 1.02 lb ai/gal propiconazole. Applications 

were targeted at Feekes growth stage 5 (BBCH 30), and 7 days prior to harvest for the forage and 

hay plots, and at 14 days prior to Feekes 10.54 (BBCH 71), and Feekes 10.54 for grain and straw 

plots. Each treated plot received two applications of azoxystrobin at 0.1195-0.1358 lb 

ai/A/application, for a total seasonal rate of 0.2475-0.2669 lb ai/A. Applications were made at 

13- to 16-day RTIs using ground equipment in spray volumes of 2.00-24.16 gal/A; applications 

were made at a 7-day RTI to treated plot 3 (grain and straw) at the C12-9035 trial site. A NIS 

was added to the spray mixtures for all applications in eleven trials, and a COC was added to the 

spray mixtures in four trials. Samples of forage and hay were harvested from all trials (with the 

exception of trial C12-9035) at PHIs of 7 and 14-20 days; grain and straw were harvested at 

maturity (PHIs of 24-64 days). Additional forage and hay samples were harvested at PHIs of 0, 

3, 7, and 21 days from two trials (in IA and TX) to assess residue decline; additional grain and 

straw samples were collected 14 and 7 days prior to, and 7 days after, maturity. Hay samples 

were dried to approximately 10-20% moisture content; drying intervals were not reported. 

Samples were analyzed for residues of azoxystrobin and its Z-isomer using an UPLC/MS/MS, 

Method RAM 305/03. The LOQ; determined as the LLMV was 0.01 ppm for each analyte. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. 

Samples were shipped from the field sites to a sample preparation facility, where they were 

homogenized prior to shipment to the analytical laboratory. Samples were stored frozen (<-10 

°C at the preparation facility and <-20 °C at the analytical laboratory) from collection to analysis 

for 52-392 days (1.7-12.9 months) for forage, 75-404 days (2.5-13.3 months) for hay, 40-452 

days (1.3-14.9 months) for grain, and 41-455 days (1.3-15.0 months) for straw. All samples 

were analyzed within 0-6 days of extraction. Adequate storage stability data are available to 

support the sample storage durations and conditions of samples from the submitted field trials. 

Following two foliar broadcast applications of the 1.18 lb ai/gal SE formulation of azoxystrobin 

at 0.2534-0.2668 lb ai/A, residues (and per trial averages) of azoxystrobin, R230310, and 

combined residues, respectively, in/on forage were: 0.0825-6.17 (0.0898-5.91), <0.01-0.207 

(<0.01-0.175), and <0.0925-6.25 (<0.0998-5.99) ppm at the 7-day PHI and 0.0289-1.65 (0.0307-

1.62), <0.01-0.0962 (<0.01-0.0870), and <0.0389-1.75 (<0.0407-1.71) ppm at the 14-20-day 

PHI; corresponding residues in/on hay were: 0.171-15.6 (0.194-14.7), <0.01-0.333 (<0.01-

0.271), and <0.181-15.8 (<0.204-14.8) ppm at the 7-day PHI and 0.0767-3.14 (0.0816-2.73), 

<0.01-0.160 (<0.01-0.138), and <0.0867-3.30 (<0.0916-2.87) ppm at the 14-20-day PHI. In/on 

grain and straw harvested at PHIs of 24-64 days following two applications at 0.2475-0.2669 lb 

ai/A, corresponding residues (and per trial averages) were: <0.01-0.0795 (<0.01-0.0764), <0.01, 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 32 of 58 

and <0.02-<0.0895 (<0.02-<0.0864) ppm in/on grain, and 0.0369-4.03 (0.0377-4.00), <0.01-

0.372 (<0.01-0.358), and <0.0469-4.37 (<0.0447-4.36) ppm in/on straw. 

The residue decline results were variable for all crop matrices. The data from both decline trials 

indicate that combined residues of azoxystrobin and R230310 in/on wheat forage and hay 

decreased with increasing PHI. In one decline trial, residues in/on grain were below the LOQ at 

all sampling intervals; therefore, residue decline could not be assessed and residues in straw 

increased from the 25-day PHI to the highest at the 39-day target PHI, and then decreased at the 

46-day PHI. In the second decline trial, combined residues in/on wheat grain and straw 

decreased from the 10- to the 17-day PHI, increased at the 24-day target PHI, and then decreased 

at the 30-day PHI. 

Table 13. Summary of Residue Data from Wheat Crop Field Trials with Azoxystrobin.

Commodity Analyte Total App. 

Rate 

(lb ai/A) 

PHI Residue Levels (ppm)1

n Sample 

Min. 

Sample 

Max. 

LAFT2 HAFT2 Median Mean Std. 

Dev. 

Forage Azoxystrobin 0.2534-

0.2668 

7 15 0.0825 6.17 0.0898 5.91 0.799 1.67 1.85 

R230310 15 <0.01 0.207 <0.01 0.175 0.0500 0.0597 0.0532

Combined 15 <0.0925 6.25 <0.0998 5.99 0.842 1.73 1.89 

Combined3 15 0.142 9.62 0.154 9.225 1.30 2.66 2.91 

Azoxystrobin 14-20 15 0.0289 1.65 0.0307 1.62 0.258 0.457 0.495 

R230310 15 <0.01 0.0962 <0.01 0.0870 0.0161 0.0266 0.0235

Combined 15 <0.0389 1.75 <0.0407 1.71 0.274 0.483 0.518 

Hay Azoxystrobin 7 15 0.171 15.6 0.194 14.7 1.28 2.79 3.82 

R230310 15 <0.01 0.333 <0.01 0.271 0.0835 0.103 0.0911

Combined 15 <0.181 15.8 <0.204 14.8 1.36 2.89 3.87 

Combined3 0.279 24.3 0.314 22.8 2.09 4.45 5.96 

Azoxystrobin 14-20 15 0.0767 3.14 0.0816 2.73 0.534 0.858 0.888 

R230310 15 <0.01 0.160 <0.01 0.138 0.0297 0.0519 0.0467

Combined 15 <0.0867 3.30 <0.0916 2.87 0.564 0.909 0.930 

Grain Azoxystrobin 0.2475-

0.2669 

24-64 15 <0.01 0.0795 <0.01 0.0764 0.0107 0.0176 0.0170

R230310 15 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A 

Combined 15 <0.02 <0.0895 <0.02 <0.0864 0.0207 0.0276 0.0170

Combined3 15 0.031 0.138 0.031 0.133 0.032 0.042 0.026 

Straw Azoxystrobin 24-64 15 0.0369 4.03 0.0377 4.00 0.546 0.991 1.14 

R230310 15 <0.01 0.372 <0.01 0.358 0.0646 0.107 0.115 

Combined 15 <0.0469 4.37 <0.0447 4.36 0.610 1.10 1.25 

Combined3 15 0.072 6.73 0.069 6.71 0.939 1.69 1.92 1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. For calculation of median, mean, and 

standard deviation, the LOQ (0.01 ppm) was used for any results reported as <LOQ in Table C.3. N/A = Not applicable. 2

 LAFT = lowest average field trial; HAFT = highest average field trial. 

3

 Adjusted combined residues. 

Conclusions. The submitted barley and wheat field trial studies are acceptable, provided Section 

F is revised. The field trials reflect the proposed use patterns for Quilt® Fungicide (EPA Reg. 

No. 100-1178 and Quilt Xcel® Fungicide (EPA Reg. No. 100-1324). Samples were analyzed for 

residues of azoxystrobin and its Z-isomer using acceptable methods, and the studies are 

supported by adequate storage stability data. The number and locations of the field trials are in 

accordance with OPPTS 860.1500. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 33 of 58 

The submitted wheat and barley data to change the PHI of forage and hay from 14-30 days to 7-

days; and replace the 45-day PHI with growth stage restriction for grain and straw is acceptable. 

The existing wheat tolerances were established using the Abound® Flowable Fungicide with up 

to two foliar applications at 0.20 lb ai/A/application for a total seasonal application rate of 0.40 

lb ai/A. Tolerances for barley are established based on translation of residue data from wheat. 

HED notes that the field trials on barley and wheat were submitted with the Quilt Xcel® 

Fungicide with lower application rates (0.13 lb ai/A/application for a total seasonal application 

rate of 0.26 lb ai/A). The residue levels were adjusted using the proportionality principle before 

deriving a tolerance level to reflect the proposed highest application rate. 

The OECD tolerance calculation procedure recommends individual tolerances of 10, 15, and 3 

ppm for barley hay, straw, and grain, respectively. HED recommends tolerances to be 

established at 15, 30, 10, and 0.15 ppm on wheat forage, hay, straw, and grain, respectively. A 

revised Section F needs to be submitted to reflect the recommended tolerances. A summary of 

tolerance recommendations is presented in Table 16. Refer to Appendix I for tolerance 

calculations. 

860.1520 Processed Food and Feed 

Ginseng

DER References: 48601201.der.doc (includes review of MRID 4860102) 

 48601203.der.doc (2008 trials) 

DP# 225494, 5/1/96, B. Schneider 

Syngenta has submitted residue data for azoxystrobin on ginseng. Two trials were conducted in 

Korea during the 2008 growing season (MRID 48601203), and two consecutive-year trials (2009 

and 2010) were conducted in Korea during the 2009-2010 growing seasons (MRIDs 48601201 

and 48601202) ( refer to the DERs for detailed residue data). 

Dried ginseng was produced by drying washed fresh ginseng root in a hot air drying machine at 

60 °C until the water content was <14%. 

Red ginseng was produced by steaming washed fresh ginseng root by steaming for 3 hours at 98 

°C. The steamed samples were dried in a hot air drying machine at 65 °C until the water content 

was ~50-55%. The smaller roots were removed and further dried in the sunlight until the water 

content was <14%. 

Samples of dried or red ginseng were processed into dried/red ginseng extracts by cutting each 

sample to about 1 cm in size and then extracting three times in a refluxing extractor with 70% 

EtOH at 70 °C or with water at 85 °C for ~18 hours. The solvents were evaporated to reach the 

65 or 72 ° Brix. 

The processed commodities were analyzed using a GLC/ECD method. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 34 of 58 

The data from the ginseng field trial indicate that residues of azoxystrobin may concentrate in 

ethanol extracts and water extracts of dried and red ginseng processed from dried ginseng and 

red ginseng bearing quantifiable residues. 

The maximum expected residue of azoxystrobin in dried and red ginseng ethanol and water 

extracts were determined by multiplying the average processing factor (see Table 14) by the 

HAFT residue of dried ginseng (see Table 9) (1.8 x 0.193 = 0.35 ppm). Since this estimate is 

below the recommended tolerance for ginseng, a processed commodity tolerance is not needed. 

Furthermore, the Agency does not typically set tolerances on ginseng processed commodities. 

The petitioner needs to submit a revised section F to propose a tolerance on ginseng at 0.5 ppm. 

Table 14. Summary of Processing Factors of Ginseng Processed Commodities with Azoxystrobin

Crop Processed 

Commodity 

Total Rate 

(lb ai/A) 

PHI 

(days) 

Processing Factor1

[Average]

Average 

Processing 

Factors 

HAFT2 x PF 

(ppm)

Ginseng Dried ginseng 

(RAC) 

1.21-2.58 7 

-- 1.8 0.35 

Dried ginseng 

Ethanol Extract 

1.0, 1.6, 3.4, 1.5, 2.2, 2.6 

[2.1] 

Dried ginseng 

Water Extract 

1.1, 1.6, 1.4, 0.8, 1.9, 1.3 

[1.4] 

Red ginseng 

(RAC) 

-- 

Red ginseng 

Ethanol Extract 

1.0, 1.5, 0.5, 1.9, 6.2, 3.3 

[2.4] 

Red ginseng Water 

Extract 

0.8, 1.5, 0.5, 1.3, 1.8, 2.0 

[1.3] 1

 Processing Factor = [Measured residue for analyte in the processed fraction] / [Measured residue for analyte in the dried RAC]. 2 The HAFT for dried ginseng equals 0.193 (0.177 x 1.09 = 0.193 it includes the metabolic factor of 0.09x); this value was used 

to estimate expected residues since tolerance is established on dried ginseng which covers red ginseng also (HAFT = 0.112). 

Wheat

DER Reference: 48681704.der1.doc 

Syngenta has submitted processing data for azoxystrobin on wheat. In two crop field trials 

conducted in LA and ND, wheat received two foliar broadcast applications of a MAI SE 

formulation (Quilt XcelTM) containing 1.18 lb ai/gal azoxystrobin and 1.02 lb ai/gal 

propiconazole. Applications were targeted at 14 days prior to Feekes 10.54, and Feekes 10.54. 

Each treated plot received two applications of azoxystrobin at an exaggerated rate (5x field rate) 

of 0.6383-0.6447 lb ai/A/application, for a total seasonal rate of 1.283 lb ai/A. Applications 

were made at 13- to 14-day RTIs using ground equipment in spray volumes of 5.29-20.04 gal/A. 

A NIS was added to the spray mixtures for both applications in one trial, and a COC was added 

to the spray mixtures at the second trial site. Wheat grain was harvested from the plots at a 30- 

to 55-day PHI and processed into AGF, bran, flour, germ, middlings, and shorts using simulated 

commercial procedures. Processing was conducted by GLP Technologies (Navasota, TX). 

Adequate descriptions were provided of the processing procedures, including material balance 

summaries. 

Samples were analyzed for residues of azoxystrobin and its Z-isomer using an UPLC/MS/MS, 

Method RAM 305/03. The LOQ; determined as the LLMV was 0.01 ppm for each analyte. The 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 35 of 58 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. 

Samples were shipped from the processor to a sample preparation facility, where they were 

homogenized prior to shipment to the analytical laboratory. Samples were stored under ambient 

conditions (field sites) and frozen (<-10 °C at the preparation facility and <-20 °C at the 

analytical laboratory) from harvest/processing to analysis. Processing took place within 398 

days of harvest. Sample analyses were completed within 181-447 days (6.0-14.7 months) for 

grain (RAC) and 42-62 days (1.4-2.0 months) for the processed commodities. All samples were 

analyzed within 0-1 days of extraction. Adequate storage stability data are available to support 

the sample storage durations and conditions of samples from the submitted wheat processing 

study. 

Following two foliar broadcast applications of the 1.18 lb ai/gal SE formulation at 1.283 lb ai/A, 

average residues of azoxystrobin, R230310, and combined residues, respectively, were: 0.0525-

0.124, <0.01-0.0123, and <0.0625-0.136 ppm in/on wheat grain (RAC); 12.1-28.1, 0.942-2.82, 

and 13.0-30.9 ppm in AGF; 0.0887-0.129, 0.0150-0.0163, and 0.104-0.145 ppm in bran; <0.01-

0.0273, <0.01, and <0.02-<0.0373 ppm in flour; 0.0115-0.0535, <0.01, and <0.0215-<0.0635 

ppm in middlings; 0.0102-0.0814, <0.01, and <0.0202-<0.0914 ppm in shorts; and 0.0851-0.114, 

<0.01-0.0134, and <0.0951-0.127 ppm in germ. The processing data indicate that combined 

residues may concentrate in AGF, bran, and germ (average processing factors of >218x, >1.4x, 

and <1.2x) but do not concentrate in flour, middlings, and shorts (average processing factors of 

<0.30x, <0.40x, and <0.50x, respectively). 

The processing factors calculated in this study were less than the maximum theoretical 

concentration factors for wheat of 7.7x for bran, 1.4x for flour, and 8.3x for shorts (based on 

separation into components; OCSPP 860.1520, Table 3). 

Table 15. Residue Data from Wheat Processing Study with Azoxystrobin.

RAC Processed 

Commodity 

Total 

Rate 

(lb ai/A) 

PHI Residues (ppm)1 [Average] Processing Factor2

Azoxystrobin R230310 Combined Azoxystrobin R230310 Combined 

Cheneyville, LA; 2009 (E17-9032) 

Wheat Grain (RAC) 1.283 30 0.129, 0.119 

[0.124] 

0.0136, 

0.0109 

[0.0123] 

0.143, 

0.130 

[0.136] 

-- -- -- 

AGF 28.1 2.82 30.9 227x 230x 227x 

Bran 0.129 0.0163 0.145 1.0x 1.3x 1.1x 

Flour 0.0273 <0.01 <0.0373 0.22x <0.82x <0.27x 

Middlings 0.0535 <0.01 <0.0635 0.43x <0.82x <0.47x 

Shorts 0.0814 <0.01 <0.0914 0.66x <0.82x <0.67x 

Germ 0.114 0.0134 0.127 0.92x 1.1x 0.94x 

Carrington, ND; 2009 (C13-9038) 

Wheat Grain (RAC) 1.283 55 0.0524, 

0.0523, 

0.0529 

[0.0525] 

<0.01, 

<0.01, 

<0.01 

[<0.01] 

<0.0624, 

<0.0623, 

<0.0629 

[<0.0625] 

-- -- -- 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 36 of 58 

Table 15. Residue Data from Wheat Processing Study with Azoxystrobin.

RAC Processed 

Commodity 

Total 

Rate 

(lb ai/A) 

PHI Residues (ppm)1 [Average] Processing Factor2

Azoxystrobin R230310 Combined Azoxystrobin R230310 Combined 

AGF 12.1 0.942 13.0 230x >94x >209x 

Bran 0.0887 0.0150 0.104 1.7x >1.5x >1.7x 

Flour <0.01 ND <0.0200 <0.19x NC3 <0.32x 

Middlings 0.0115 <0.01 <0.0215 0.22x NC <0.34x 

Shorts 0.0102 <0.01 <0.0202 0.19x NC <0.32x 

Germ 0.0851 <0.01 <0.0951 1.6x NC <1.5x 

Average4

Wheat Grain (RAC) 1.283 30-

55 

-- -- -- 

AGF 228x >162x >218x 

Bran 1.4x >1.4x >1.4x 

Flour <0.21x <0.91x <0.30x 

Middlings 0.33x <0.91x <0.40x 

Shorts 0.43x <0.91x <0.50x 

Germ 1.3x <1.1x <1.2x 1

 The LOQ was 0.01 ppm for all analytes in all matrices. Per trial average residues were calculated by the study reviewer using

the LOQ for all residues reported as <LOQ. ND = Not detected. Residues were not adjusted. 2

 Processing Factor = [Measured residue for analyte in the processed fraction] / [Measured residue for analyte in the grain RAC]. 3

 NC = Not calculated; residues were below the LOQ in both RAC and processed fraction. 4

 In the calculation of the average processing factor, a value of 1.0 was used when a processing factor was not calculated due to 

residues <LOQ in the processed fraction. 

Conclusions: The data from the wheat processing study indicate that residues of asoxystrobin 

concentrate in aspirated grain fractions (218x), bran (1.4x), and germ (1.2x), but not in flour, 

middlings, and shorts 0.3x, 0.4x, 0.5x, respectively following processing of the RAC (wheat 

grain) with quantifiable residues. 

Based on the HAFT for wheat grain 0.133 ppm (see Table 13) and concentration factor of 218x 

for aspirated grain fractions, the maximum expected residues would be 29 ppm. An aspirated 

grain fractions tolerance was established previously at 420 ppm based on sorghum. The 

maximum expected residue in wheat bran is 0.19 ppm (1.4x x 0.133 = 0.19); the established 

tolerance of wheat bran (0.20 ppm) needs to be removed from the 40 CFR with establishment of 

wheat grain tolerance at 0.2 ppm. Based on the HAFT for wheat grain of 0.133 ppm and the 

1.2x concentration factor for germ, expected residues in wheat germ would be 0.16 ppm, which 

is close to the recommended tolerance for wheat grain of 0.2 ppm; therefore, a tolerance for 

wheat germ is not needed. 

The data from the ginseng field trial indicate that residues of azoxystrobin may concentrate in 

ethanol extracts and water extracts of dried and red ginseng processed from dried ginseng and 

red ginseng bearing quantifiable residues. 

The maximum expected residue of azoxystrobin in dried and red ginseng ethanol and water 

extracts is 0.35 ppm. Since this estimate is below the recommended tolerance for ginseng, a 

processed commodity tolerance is not needed. Furthermore, the Agency does not typically set 

tolerances on ginseng processed commodities. The petitioner needs to submit a revised section F 

to propose a tolerance on ginseng at 0.5 ppm 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 37 of 58 

860.1650 Submittal of Analytical Reference Standards 

Analytical standards for azoxystrobin and its Z-isomer (R230310) are currently available in the 

EPA National Pesticide Standards Repository (personal communication between T. Cole, ACB, 

and Versar, 4/30/12). The standards will expire in 2014 and 2013, respectively. 

860.1850 Confined Accumulation in Rotational Crops 

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

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

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, N. Dodd, 2/6/03

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

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

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 use 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. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 38 of 58 

Conclusions: Because the proposed amended uses do not result in increased maximum seasonal 

application rates of azoxystrobin, no changes to the existing rotational crop restrictions are 

needed. Subsequent to the establishment of tolerances in/on oat and rye, rotational crop 

restrictions on oat and rye should be removed. HED assumes the rotational crop restrictions 

specified on the Quilt labels are due to use of propioconazole. Rotational crop data is not 

required on ginseng. 

860.1550 Proposed Tolerances

DP# 225494, 5/1/96, B. Schneider 

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 the petitioner 

for plants is appropriate, but need to be revised for livestock commodities to remove the Zisomer. 

The submitted crop field trial data for ginseng are adequate for purposes of establishing an 

import tolerance. The OECD tolerance statistical calculation procedures (March 2011) were 

used in determining appropriate tolerance levels. For ginseng, because samples were not 

analyzed for the Z-isomer, a metabolic factor of 0.09x was applied to the results for azoxystrobin 

to account for residues of the Z-isomer in the tolerance calculation. The proposed and 

recommended tolerances are presented in Table 16. 

The proposed tolerance for ginseng extracts (red ginseng extract and ginseng extract) at 0.5 ppm 

needs to be revised. A revised Section F needs to be submitted to propose a tolerance of 0.50 

ppm on ginseng. 

The residue definitions for plants and livestock are not harmonized with Codex; the US and the 

Canadian residue definitions include both the predominant E isomer and the minor Z isomer 

whereas the Codex includes only the E isomer. 

Codex maximum residue limits (MRLs) are established for azoxystrobin on ginseng at 0.1 ppm 

and dry ginseng including red ginseng at 0.5 ppm. A proposed MRL ginseng, processed 

products at 0.5 ppm has been returned to JMPR for further consideration of the processing study 

(Report of the 44th Session of the CCPR, April 2012, paragraph 59 and Appendix III). 

Canadian MRLs have been established for residues of azoxystrobin including the (Z)-isomer on 

ginseng roots at 0.5 ppm and at 0.03 ppm for barley, oats, rye, and wheat which are not in 

agreement with the US tolerances, except for ginseng roots. Mexico adopts US tolerances and/or 

Codex MRLs for its export purposes. The Codex MRLs on barley grain and wheat grain are 

estimated at 0.5 and 0.2 ppm, respectively and MRLs for oats and rye are extrapolated from the 

data on barley and wheat, respectively. The US tolerances on oat grain (1.5 ppm) and barley 

grain (3 ppm) could not be harmonized since the Codex MRLs are lower. Setting the US 

tolerance to be consistent with the Codex MRLs might lead to residues in excess of the tolerance, 

despite legal use of the pesticide in accordance with the registered label. 

HED recommends increasing the US tolerances of ginseng to 0.5 ppm, and rye grain and wheat 

grain to 0.2 ppm to harmonize with the numerical portion of the Codex MRL. The US is not 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 39 of 58 

establishing a tolerance on ginseng (fresh roots) since the dried ginseng covers the fresh roots. 

Ginseng 

The Codex and US tolerances are based on field trials conducted in Korea at the maximum GAP 

with 4 foliar applications of azoxystrobin at 10 days interval at a rate of 0.34–0.56 kg ai/ha (0.5 

lb ai/A) with a PHI of 7 days. The maximum residue was 0.05 mg/kg. The Meeting estimated a 

maximum residue level of 0.1 mg/kg and an STMR of 0.025 mg/kg. Based on processing, 0.5 

mg/kg for ginseng, processed products (dried, red, ethanol and water extracts) was estimated. 

The US tolerance for ginseng is recommended at 0.5 ppm based on the same data. The US 

tolerance was estimated using the OECD calculation procedures and was adjusted upward from 

0.4 ppm to 0.5 ppm to harmonize with Codex. 

Oat and Rye 

The Codex MRLs are based on field trials conducted in Europe. Trials on barley and wheat were 

conducted at the GAP rate (± 30%) of 0.25 kg ai/ha (0.223 lb ai/A), 2–3 applications, and a PHI 

of 35–42 days. The MRL for oats was extrapolated from the data on barley grain and MRL for 

rye from data on wheat grain which. The highest residues were 0.28 and 0.14 ppm, respectively. 

The MRL was estimated at 0.5 ppm on oat grain and at 0.20 ppm on rye grain. The US 

tolerances on oats (1.5 ppm) and on rye (0.1 ppm) was based on field trial data conducted on oat 

and rye at 0.26 lb ai/A with PHIs of 25-48 and 34-50, respectively. The rye grain tolerance (0.1 

ppm) was increased to 0.2 ppm to harmonize with Codex. 

Table 16. Tolerance Summary for Azoxystrobin 

Commodity Proposed Tolerance 

(ppm) 

Recommended 

Tolerance (ppm) 

Comments; Correct Commodity 

Definition

Ginseng Extract (Red 

Ginseng Extract and 

Ginseng Extract) 

0.5 -- The US does not currently regulate 

any processed commodity of ginseng; 

therefore, this tolerance is not 

needed. 

Ginseng -- 0.50 Based on data for dried ginseng root/ 

to harmonize with Codex. 

Oat, forage 4 5.0 

Oat, hay 7 10.0 

Oat, straw 3 3.0 

Oat, grain 1 1.50 

Rye, forage 4 7.0 

Rye, straw 0.8 1.50 

Rye, grain 0.07 0.20 To harmonize with Codex. 

Barley, hay 7 10.0 

Barley, straw 8 15.0 

Barley, grain 2 3.0 

Wheat, forage 10 15.0 

Wheat, straw 6 10.0 

Wheat, hay 20 30.0 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 40 of 58 

Grain, aspirated fractions 460 

(Established at 420) 

420 The established tolerance of 420 ppm 

is sufficient. 

Grain, aspirated grain fractions 

Tolerance That Need To be Revised

Wheat, grain Not proposed 

(Established at 0.10) 

0.20 Based on data/to harmonize with 

Codex. 

 Livestock Commodities Requested To be Revised

Cattle, fat 0.3 Not Needed 

Hog, fat 0.1 

Hog, meat 0.02 

Livestock Commodities Requested to be Established

Poultry, meat 0.01 Not Needed 

Poultry, liver 0.2 

Poultry, fat 0.01 

Egg 0.1 

Cattle, liver 0.5 

Cattle, kidney 0.1 

Hog, liver 0.2 

Hog, kidney 0.03 

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: 235342 

Subject: Azoxystrobin Method Validation of Method 243/04. 

From: C. Stafford 

To: E. Haeberer 

Dated: 5/30/97 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 41 of 58 

MRIDs: MRID 44915207 

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#: 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 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 42 of 58 

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-ofRegistration 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 

DP#s: 362963 and 3363046 

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. 

From: M. Negussie 

To: T. Kish/B. Madden 

Dated: 8/20/09 

MRIDs: 47486501 

Subject: Pesticide Residues in Food 2011. Report 2011. 

From: Joint FAO/WHO Meeting on Pesticide Residues 

 To: Publication (http://www.fao.org) 

Dated: 2011 

Attachments: 

International Residue Limit Status sheet 

Appendix I - Tolerance Assessment Calculations 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 43 of 58 

International Residue Limits 

Azoxystrobin (PC Code 128810; 08/22/12) 

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition: 

US Canada Mexico2 Codex3

40 CFR 180.507: 

Plant: sum of azoxystrobin, 

[methyl( E )-2-(2-(6-(2-

cyanophenoxy) pyrimidin-4-

yloxy)phenyl)-3-

methoxyacrylate], and the Zisomer of azoxystrobin [methyl( Z 

)-2-(2-(6-(2-

cyanophenoxy)pyrimidin-4-

yloxy)phenyl)-3 methoxyacrylate] 

(αE)-methyl 2-[[6-(2-

cyanophenoxy)-4-

pyrimidinyl]oxy]-α -

methoxymethylene)benzene

acetate, 

including the isomer (Z)-

methyl 2-[[6-(2- 

cyanophenoxy)-4-

pyrimidinyl]oxy]--

(methoxymethylene)benzen

eacetate 

 Azoxystrobin. 

The residue is fat 

soluble. 

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg) 

US Canada Mexico2 Codex3

Ginseng 0.50 0.5 ginseng roots 0.1Ginseng 

0.5 Ginseng, dried 

including red ginseng 

0.5 ginseng, processed 

products (proposed) 

Oat, forage 5.0 

Oat, hay 10.0 

Oat, straw 3.0 15 straw and fodder of 

cereal grains 

Oat, grain 1.50 0.03 0.5 

Rye, forage 7.0 

Rye, straw 1.50 15 straw and fodder of 

cereal grains 

Rye, grain 0.20 0.03 0.2 

Barley, hay 10.0 

Barley, straw 15.0 15 straw and fodder of 

cereal grains 

Barley, grain 3.0 0.03 0.5 

Wheat, forage 15.0 

Wheat, straw 10.0 15 straw and fodder of 

cereal grains 

Wheat, hay 30.0 

Wheat, grain 0.20 0.03 0.2 

Grain, aspirated grain 

fractions* 

420 

Completed: M. Negussie; 08/31/2012 

1

 Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant. *The established tolerance should remain at 420 ppm. 

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes. 

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = 

processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 44 of 58 

fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC. 

Appendix I. Tolerance Assessment Calculations.

Ginseng

The OECD tolerance statistical calculation procedures (March 2011 version) were used for 

calculating the recommended tolerances. The statistical goal of the OECD calculation 

procedures is to produce an MRL proposal in the region of the 95th percentile of the underlying 

residues distribution. 

The dataset used to establish a tolerance for combined residues of azoxystrobin and its Z-isomer 

on ginseng consisted of field trial data representing application rates of 1.21-1.98 lb ai/A (four 

applications at 0.300-0.496 lb ai/A/application) with a 7-day PHI. The dataset includes results 

for two trials reflecting 2-year consecutive-year applications. The field trial PHIs are within 

25% of the minimum label PHI. 

Based on the additional use pattern information submitted, the maximum label rate is 1.36 lb 

ai/A; the application rate of 1.98 lb ai/A for two of the four 1-year trials > 25% of the maximum 

label rate. The application rate of the other two trials (1.21-1.29 lb ai/A) are within 25% of the 

maximum label rate. HED has concluded that inclusion of all data is appropriate for 

determination of a tolerance for ginseng. 

Samples from the submitted field trials were analyzed for residues of azoxystrobin only. To 

account for residues of the Z-isomer, the petitioner proposed a worst-case metabolic factor of 

0.09x, determined from the existing root crop data reflecting analysis for residues of 

azoxystrobin and the Z-isomer. This factor was applied to the residue results for calculation of 

the recommended tolerance level. Tolerance calculations reflecting data from the extrapolated 

results are presented in Table I-1. 

The average residues values used to calculate the tolerance are provided in Table I-1. Residues 

of azoxystrobin were quantifiable (LOQ = 0.003 or 0.02 ppm) in/on all samples of dried ginseng. 

Using the OECD tolerance calculation procedures and extrapolation of azoxystrobin residues to 

account for residues of the Z-isomer, the recommended tolerance for combined residues of 

azoxystrobin and its Z-isomer in/on ginseng is 0.4 ppm. HED notes that the recommended 

tolerance would be the same without extrapolation. 

Oats, Rye, Wheat, and Barley

The dataset used to establish tolerances for combined residues of azoxystrobin and its Z-isomer 

on oats, rye, barley, and wheat consisted of field trial data representing application rates of 0.24-

0.26 lb ai/A with a 7-day PHI for forage and hay. The field trial application rates and PHIs are 

within 25% of the maximum label application rate, except for the proposed uses for the Abound 

label. The recommended tolerances using the OECD statistical calculation procedures are 

adjusted using the proportionality principle. The residue values entered into the OECD tolerance 

spreadsheet are provided in Table I-1-5. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 45 of 58 

Based on the available data and using the OECD statistical calculation procedures, the proposed 

tolerances for the proposed commodities of oats, rye, barley, and wheat must be revised to reflect 

the appropriate tolerance levels estimated and commodity definition as listed in Table 16. 

Table I-1. Residue data used to calculate tolerance for azoxystrobin in/on ginseng.

Regulator: EPA 

Chemical: Azoxystrobin 

Crop: Ginseng 

PHI: 7 Days 

App. Rate: 1.21-1.98 lb ai/A 

Submitter: Syngenta Crop Protection, Inc. 

MRID Citation: MRIDs 48601201, 48601202, and 48601203 

Combined Residues of Azoxystrobin and the 

Z-isomer Based on Extrapolation (ppm)1 

Residues of Azoxystrobin (ppm)

1-Year Data 0.037 0.034 

0.052 0.048 

0.13 0.12 

0.14 0.13 

2-Year Data 0.069 0.063 

0.193 0.177 1

 A 0.09x metabolic factor was applied to the Korean data and then added to reported residues for azoxystrobin per 

se. 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 46 of 58 

 

Total number of data (n) 6

Percentage of censored data 0%

Number of non-censored data 6

Lowest residue 0.037

Highest residue 0.193

Median residue 0.100

Mean 0.104

Standard deviation (SD) 0.061

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.193

- Mean + 4 SD 0.346

- CF x 3 Mean 0.311

Unrounded MRL 0.346

Rounded MRL 0.4

 High uncertainty of MRL estimate.

[Small dataset]

1.21-1.98 lb ai/A; 7-day PHI

Azoxystrobin

Ginseng (extrapolated; including 2-yr data)

Korea
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 47 of 58 

Table I-2. Residue data used to calculate tolerance for azoxystrobin in/on rye

Regulator: EPA EPA EPA 

Chemical: Azoxystrobin Azoxystrobin Azoxystrobin 

Crop: Rye, forage Rye, grain Rye, straw 

PHI: 6-8 Days 34-50 Days 34-50 Days 

App. Rate: 0.257-0.262 lb ai/A 0.256-0.265 lb ai/A 0.256-0.265 lb ai/A 

Submitter: Syngenta Syngenta Syngenta

MRID Citation: MRID 48681701 MRID 48681701 MRID 48681701 

Combined Residues of Azoxystrobin and the Z-isomer (ppm)

1.756 0.039 0.280

2.295 0.031 0.162

2.433 0.031 0.266

1.663 0.031 0.638

 

 Azoxystrobin 

 Rye, forage 

 EPA 

 0.257-0.262 lb ai/A 

 

 Total number of data (n) 4 

 Percentage of censored data 0% 

 Number of non-censored data 4 

 Lowest residue 1.663 

 Highest residue 2.433 

 Median residue 2.025 

 Mean 2.037 

 Standard deviation (SD) 0.384 

 Correction factor for censoring (CF) 1.000 

 

 Proposed MRL estimate 

 

 - Highest residue 2.433 

 - Mean + 4 SD 3.572 

 - CF x 3 Mean 6.110 

 Unrounded MRL 6.110 

 

 Rounded MRL 7 

 

 High uncertainty of MRL estimate. 

 [Small dataset] 

 

 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 48 of 58 

 Azoxystrobin 

 Rye, grain 

 EPA 

 0.256-0.265 lb ai/A 

 

 Total number of data (n) 4 

 Percentage of censored data 0% 

 Number of non-censored data 4 

 Lowest residue 0.031 

 Highest residue 0.039 

 Median residue 0.031 

 Mean 0.033 

 Standard deviation (SD) 0.004 

 Correction factor for censoring (CF) 1.000 

 

 Proposed MRL estimate 

 

 - Highest residue 0.039 

 - Mean + 4 SD 0.048 

 - CF x 3 Mean 0.098 

 Unrounded MRL 0.098 

 

 Rounded MRL 0.1 

 

 High uncertainty of MRL estimate. 

 [Small dataset] 

 

 

 Azoxystrobin 

 Rye, straw 

 EPA 

 0.256-0.265 lb ai/A 

 

 Total number of data (n) 4 

 Percentage of censored data 75% 

 Number of non-censored data 1 

 Lowest residue 0.162 

 Highest residue 0.638 

 Median residue 0.273 

 Mean 0.336 

 Standard deviation (SD) 0.208 

 Correction factor for censoring (CF) 0.500 

 

 Proposed MRL estimate 

 

 - Highest residue 0.638 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

Page 49 of 58 

 - Mean + 4 SD 1.167 

 - CF x 3 Mean 0.505 

 Unrounded MRL 1.167 

 

 Rounded MRL 1.5 

 

 High uncertainty of MRL estimate. 

 [Small dataset and high level of censoring] 

 

Table I-3. Residue data used to calculate tolerance for azoxystrobin in/on Oats

Regulator: EPA EPA EPA 

Chemical: Azoxystrobin Azoxystrobin Azoxystrobin Azoxystrobin 

Crop: Oats, forage Oats, hay Oats, grain Oats, straw 

PHI: 7 Days 7 Days 25-48 Days 25-48 Days 

App. Rate: 0.249-0.265 lb ai/A 0.249-0.265 lb ai/A 0.253-0.270 lb ai/A 0.253-0.270 lb ai/A 

Submitter: Syngenta Syngenta Syngenta Syngenta

MRID 

Citation: 

MRID 48681703 MRID 48681703 MRID 48681703 MRID 48681703 

Combined Residues of Azoxystrobin and the Z-isomer (ppm)

0.821 1.445 0.684 1.200 

3.219 5.174 0.111 1.261 

0.416 0.691 0.057 0.249 

0.323 0.434 0.059 0.148 

0.183 0.326 0.088 0.129 

1.910 5.082 0.328 1.295 

2.187 3.542 0.090 0.564 

1.374 2.033 0.209 0.331 

1.255 5.067 0.035 0.130 

0.724 1.078 0.096 1.064 

1.586 1.833 0.675 1.555 

 

 

 Azoxystrobin 

 Oats, forage 

 EPA 

 0.249-0.265 lb ai/A 

 

 Total number of data (n) 11 

 Percentage of censored data 36% 

 Number of non-censored data 7 

 Lowest residue 0.183 

 Highest residue 3.219 

 Median residue 1.255 

 Mean 1.272 
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 Standard deviation (SD) 0.920 

 Correction factor for censoring (CF) 0.758 

 

 Proposed MRL estimate 

 

 - Highest residue 3.219 

 - Mean + 4 SD 4.953 

 - CF x 3 Mean 2.892 

 Unrounded MRL 4.953 

 

 Rounded MRL 5 

 

 

 

 

 

 Azoxystrobin 

 Oats, hay 

 EPA 

 0.249-0.265 lb ai/A 

 

 Total number of data (n) 11 

 Percentage of censored data 36% 

 Number of non-censored data 7 

 Lowest residue 0.326 

 Highest residue 5.174 

 Median residue 1.833 

 Mean 2.428 

 Standard deviation (SD) 1.936 

 Correction factor for censoring (CF) 0.758 

 

 Proposed MRL estimate 

 

 - Highest residue 5.174 

 - Mean + 4 SD 10.173 

 - CF x 3 Mean 5.518 

 Unrounded MRL 10.173 

 

 Rounded MRL 10 

 

 

 

 
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 Azoxystrobin 

 Oats, grain 

 EPA 

 0.253-0.270 lb ai/A 

 

 Total number of data (n) 11 

 Percentage of censored data 36% 

 Number of non-censored data 7 

 Lowest residue 0.035 

 Highest residue 0.684 

 Median residue 0.096 

 Mean 0.221 

 Standard deviation (SD) 0.241 

 Correction factor for censoring (CF) 0.758 

 

 Proposed MRL estimate 

 

 - Highest residue 0.684 

 - Mean + 4 SD 1.186 

 - CF x 3 Mean 0.503 

 Unrounded MRL 1.186 

 

 Rounded MRL 1.5 

 

 

 

 

 

 Azoxystrobin 

 Oats, straw 

 EPA 

 0.253-0.270 lb ai/A 

 

 Total number of data (n) 11 

 Percentage of censored data 36% 

 Number of non-censored data 7 

 Lowest residue 0.129 

 Highest residue 1.555 

 Median residue 0.564 

 Mean 0.721 

 Standard deviation (SD) 0.556 

 Correction factor for censoring (CF) 0.758 

 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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 Proposed MRL estimate 

 

 - Highest residue 1.555 

 - Mean + 4 SD 2.945 

 - CF x 3 Mean 1.638 

 Unrounded MRL 2.945 

 

 Rounded MRL 3 

 

 

 

 

Table I-4. Residue data used to calculate tolerance for azoxystrobin in/on Barley.

Regulator: EPA EPA EPA 

Chemical: Azoxystrobin Azoxystrobin Azoxystrobin 

Crop: Barley, hay Barley, grain Barley, straw 

PHI: 7 Days 16-49 Days 16-49 Days 

App. Rate: 0.253-0.267 lb ai/A 0.256-0.265 lb ai/A 0.256-0.265 lb ai/A

Submitter: Syngenta Syngenta Syngenta

MRID Citation: MRID 48681702 MRID 48681702 MRID 48681702 

Combined Residues of Azoxystrobin and the Z-isomer (ppm)

5.082 0.340 5.590 

0.772 0.036 0.231 

0.722 0.058 0.420 

1.392 0.045 0.473 

1.250 0.072 1.180 

2.218 0.031 0.156 

6.098 0.551 5.960 

3.357 1.679 4.374 

1.104 0.094 0.581 

 

 Azoxystrobin 

 Barley, Hay 

 EPA 

 0.253-0.264lb ai/A 

 

 Total number of data (n) 9 

 Percentage of censored data 33% 

 Number of non-censored data 6 

 Lowest residue 0.722 

 Highest residue 6.098 

 Median residue 1.392 
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 Mean 2.444 

 Standard deviation (SD) 1.978 

 Correction factor for censoring (CF) 0.778 

 

 Proposed MRL estimate 

 

 - Highest residue 6.098 

 - Mean + 4 SD 10.354 

 - CF x 3 Mean 5.703 

 Unrounded MRL 10.354 

 

 Rounded MRL 10 

 

 

 

 

 

 Azoxystrobin 

 Barley, grain 

 EPA 

 0.257-0.262 lb ai/A 

 

 Total number of data (n) 9 

 Percentage of censored data 44% 

 Number of non-censored data 5 

 Lowest residue 0.031 

 Highest residue 1.679 

 Median residue 0.072 

 Mean 0.323 

 Standard deviation (SD) 0.539 

 Correction factor for censoring (CF) 0.704 

 

 Proposed MRL estimate 

 

 - Highest residue 1.679 

 - Mean + 4 SD 2.477 

 - CF x 3 Mean 0.682 

 Unrounded MRL 2.477 

 

 Rounded MRL 3 

 

 

 

 

 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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 Azoxystrobin 

 Barley, straw 

 EPA 

 0.257-0.262 lb ai/A 

 

 Total number of data (n) 9 

 Percentage of censored data 44% 

 Number of non-censored data 5 

 Lowest residue 0.156 

 Highest residue 5.960 

 Median residue 0.581 

 Mean 2.107 

 Standard deviation (SD) 2.453 

 Correction factor for censoring (CF) 0.704 

 

 Proposed MRL estimate 

 

 - Highest residue 5.960 

 - Mean + 4 SD 11.920 

 - CF x 3 Mean 4.448 

 Unrounded MRL 11.920 

 

 Rounded MRL 15 

 

 

 

 
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Table I-5. Residue data used to calculate tolerance for azoxystrobin in/on Wheat.

Regulator: EPA EPA EPA 

Chemical: Azoxystrobin Azoxystrobin Azoxystrobin Azoxystrobin 

Crop: Wheat, forage Wheat, hay Wheat, grain Wheat, straw 

PHI: 7 Days 7 Days 24-64 Days 24-64 Days 

App. Rate: 0.253-0.267 lb ai/A 0.253-0.267 lb ai/A 0.248-0.267 lb ai/A 0.248-0.267 lb ai/A 

Submitter: Syngenta Syngenta Syngenta Syngenta

MRID 

Citation: 

MRID 48681704 MRID 48681704 MRID 48681704 MRID 48681704

Combined Residues of Azoxystrobin and the Z-isomer (ppm)

6.730 6.329 0.042 6.714 

0.433 1.003 0.037 2.880 

0.154 0.314 0.031 0.069 

0.286 0.373 0.031 0.169 

1.848 4.712 0.039 1.252 

9.225 22.792 0.032 1.423 

0.394 1.129 0.031 0.316 

0.598 0.901 0.031 0.839 

1.237 2.772 0.031 0.121 

4.635 4.019 0.031 0.280 

1.540 0.425 0.133 4.297 

5.421 8.747 0.033 2.633 

5.806 10.149 0.055 3.234 

1.297 2.094 0.050 0.939 

0.303 0.981 0.031 0.176 

 

 Azoxystrobin 

 Wheat, forage 

 EPA 

 0.253-0.267 lb ai/A 

 

 Total number of data (n) 15 

 Percentage of censored data 27% 

 Number of non-censored data 11 

 Lowest residue 0.154 

 Highest residue 9.225 

 Median residue 1.297 

 Mean 2.660 

 Standard deviation (SD) 2.912 

 Correction factor for censoring (CF) 0.822 

 

 Proposed MRL estimate 

 

 - Highest residue 9.225 
Azoxystrobin Summary of Analytical Chemistry and Residue Data DP#: 397692 

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 - Mean + 4 SD 14.307 

 - CF x 3 Mean 6.562 

 Unrounded MRL 14.307 

 

 Rounded MRL 15 

 

 

 

 

 

 Azoxystrobin 

 Wheat, hay 

 EPA 

 0.253-0.267 lb ai/A 

 

 Total number of data (n) 15 

 Percentage of censored data 27% 

 Number of non-censored data 11 

 Lowest residue 0.314 

 Highest residue 22.792 

 Median residue 2.094 

 Mean 4.449 

 Standard deviation (SD) 5.958 

 Correction factor for censoring (CF) 0.822 

 

 Proposed MRL estimate 

 

 - Highest residue 22.792 

 - Mean + 4 SD 28.282 

 - CF x 3 Mean 10.975 

 Unrounded MRL 28.282 

 

 Rounded MRL 30 

 

 

 

 

 

 Azoxystrobin 

 Wheat, grain 

 EPA 

 0.248-0.267 lb ai/A 

 

 Total number of data (n) 15 
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 Percentage of censored data 0% 

 Number of non-censored data 15 

 Lowest residue 0.031 

 Highest residue 0.133 

 Median residue 0.032 

 Mean 0.042 

 Standard deviation (SD) 0.026 

 Correction factor for censoring (CF) 1.000 

 

 Proposed MRL estimate 

 

 - Highest residue 0.133 

 - Mean + 4 SD 0.147 

 - CF x 3 Mean 0.127 

 Unrounded MRL 0.147 

 

 Rounded MRL 0.15 

 

 

 

 

 

 Azoxystrobin 

 Wheat, straw 

 EPA 

 0.248-0.267 lb ai/A 

 

 Total number of data (n) 15 

 Percentage of censored data 7% 

 Number of non-censored data 14 

 Lowest residue 0.069 

 Highest residue 6.714 

 Median residue 0.939 

 Mean 1.690 

 Standard deviation (SD) 1.924 

 Correction factor for censoring (CF) 0.956 

 

 Proposed MRL estimate 

 

 - Highest residue 6.714 

 - Mean + 4 SD 9.387 

 - CF x 3 Mean 4.843 

 Unrounded MRL 9.387 

 

 Rounded MRL 10 
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