UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

Date: 8/5/20 15 

SUBJECT: Diflubenzuron. Petition for the Establishment of Permanent Tolerances and 

Registration for New uses on Alfalfa and Carrot; and Crop group Expansion for 

Peach Subgroup 12-l 2B; Plum Subgroup I 2- I 2C; Nut, Tree, Group 14; and 

Pepper/Eggplant Subgroup 8-1 OB. Summary of Analytical Chemistry and 

Residue Data. 

PC Code: 10820 I 

Decision No.: 4941 16 

Petition No.: 4E8306 

DP Barcode: D423328 

Registration No.: 400-46 1 

Regulatory Action: Section 3 Registration 

Risk Assessment Type: NA Reregistration Case No.: 144 

TXR No.: NA CAS No.: 35367-38-5 

MRID Nos.: 493995-0 I, 493995-02, 

493995-03, 493995-04,493995-05 

40 CFR: § 180.377 

FROM: Sumitra Bose Biswas, Chemist ~~c(; · ~~ 1

" 

Risk Assessment Branch VT 

Health Effects Division (7509P) 

THROUGH: George Kramer, PhD, Chemist, De gn ate i er ~-- Tom Bloem, Chemist, Designated Review 

Science Advisory Council for Chemistry (ChemS ) 

HED (7509P) 

And 

Donna S. Davis, Acting Branch Chief 

Risk Assessment Branch VI 

Health Effect Division (7509P) 

TO: Andrew Ertman/Barbara Madden 

Risk Integration, Minor Use & Emergency Response Branch 

Registration Division (RD) (7505P) 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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Table of Contents 

1.0 Executive Summary ............................................................................................................. 5

2.0 Regulatory Recommendations ............................................................................................. 6

2.1 Data Deficiencies/Data Needs .......................................................................................... 7

2.2 Tolerance Considerations ................................................................................................. 7

2.2.1 Enforcement Analytical Method ............................................................................... 7

2.2.2 Recommended Tolerances ........................................................................................ 8

2.2.3 Revisions to Petitioned-For Tolerances .................................................................... 9

2.2.4 International Harmonization ..................................................................................... 9

2.3 Label Recommendations .................................................................................................. 9

3.0 Introduction ........................................................................................................................ 10

3.1 Chemical Identity ........................................................................................................... 10

3.2 Physical/Chemical Characteristics ................................................................................. 10

3.3 Pesticide Use Pattern/Directions for Use (860.1200) ..................................................... 11

4.0 Metabolite/Degradate Residue Profile ............................................................................... 12

4.1 Summary of Plant Metabolism and Residues of Concern (860.1300) ....................... 12

4.2 Summary of Livestock Metabolism and Residues of Concern (860.1300) ................... 12

4.3 Summary of Confined Rotational Crops and Residues of Concern (860.l850) ............. 12

5.0 Residue Profile ................................................................................................................... 13

5.1 Residue Analytical Methods (860.1340) ........................................................................ 13

5.1.1 Data Collection Methods ........................................................................................ 13

5.1.2 Multi-Residue Methods (860.1360) ........................................................................ 16

5.1.3 Tolerance Enforcement Methods ............................................................................ 16

5.1.4 Submittal of Analytical Reference Standards (860.1650) ...................................... 16

5.2 Storage Stability (860.1380) .......................................................................................... 16

5.3 Residue Data .................................................................................................................. 18

5.3.1 Crop Field Trials (860.1500) .................................................................................. 18

5.3.2 Field Rotational Crops (860.1900) ......................................................................... 25

5.3.3 Processed Food and Feed (860.1520) ..................................................................... 26

5.3.4 Meat, Milk, Poultry, and Eggs (860.1480) ............................................................. 26

5.3.5 Food Handling (860.1460) ...................................................................................... 28

5.3.6 Water, Fish, and Irrigated Crops (860.1400) .......................................................... 28

6.0 Tolerance Derivation ......................................................................................................... 29

Attachment 1. Trial Number and Geographic Location Tables ................................................... 29

Attachment 2. Individual Sample and Average Field Trial Results ............................................ 30

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Attachment 3. International Residue Limit Status Sheet ............................................................. 34

Attachment 4. OECD MRL Calculator Inputs and Results ......................................................... 36

 

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Summary of Submitted Residue Chemistry Studies 

OPPTS 860 

Series 

Guideline 

MRID Number Title 

860.1500 493995-01 William P. Barney (2015); Diflubenzuron: Magnitude of the Residue on Alfalfa. 

860.1340 493995-02 William P. Barney, Kathryn Homa (2015); Diflubenzuron: Magnitude of the Residue on 

Alfalfa. 

860.1900 493995-03 K. S. Samoil (2015); Diflubenzuron: Magnitude of the Residue on Carrot. 

860.1850 

860.1900 

493995-04 William P. Barney (2013); Diflubenzuron: Magnitude of the Residue on Peach and Plum. 

493995-05 R. W. Russel (2008), Dimilion 2L in Peaches and Plums: Magnitude of the Residue Study. 

 

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1.0 Executive Summary 

Diflubenzuron, (N-[((4-chlorophenyl)amino)carbonyl]-2,6-difluorobenzamide), a member of the 

urea-derivative chemical family, is classified as an insect growth regulator and is used as both an 

acaricide and insecticide. It is currently registered in the U.S. for use as a chitin inhibitor 

(prevents development from the immature to the juvenile and adult stages). The main agriculture 

pests targeted for control with diflubenzuron are twig borer, stink bug, grasshopper, beet 

armyworm, soybean looper, rust mite, artichoke plume moth, and peanuts root knot nematode. 

Tolerances for residues of diflubenzuron, currently established under 40 CFR §180.377, range 

from 0.02-55 ppm. 

The Interregional Research Project No. 4 (IR-4) is requesting a Section 3 Registration for 

Dimilin® 2L, an aqueous flowable formulation of diflubenzuron, and the establishment of 

permanent tolerances as described below: 

 A new use of diflubenzuron on carrot on the Dimilin® 2L labels and a tolerance for 

carrot, roots at 0.2 ppm. 

 A new regionally restricted use of diflubenzuron on alfalfa and establishment of 

tolerances for residues on alfalfa forage, hay, and seed at 6 ppm, 20 ppm, and 0.9 ppm, 

respectively. The new use is to be included on the label for Dimilin® 2L. The propose 

uses are limited to states west of the Mississippi river. 

 Expansion of the proposed use of diflubenzuron on peach to include all commodities in 

the updated peach crop subgroup (CSG) 12-12B on the Dimilin® 2L label and a 

tolerance for residues on peach CSG 12-12B at 0.5 to harmonize with the Codex MRLs. 

 Expansion of the proposed use of diflubenzuron on plum to include all the commodities 

in the updated plum CSG 12-12C on the Dimilin® 2L label and a tolerance for residues 

on plum CSG 12-12C at 0.5 to harmonize with the Codex MRLs. Additionally, a separate 

tolerance for residues on plum, prune, dried at 0.5 ppm was petitioned for. 

 Expansion of the current use of diflubenzuron on pepper to include all commodities in the 

updated pepper/eggplant crop CSG 8-10B on the Dimilin® 2L label and a tolerance for 

residues on pepper/eggplant CSG 8-10B at 1.0 ppm. 

 Expansion of the current use of diflubenzuron on cotton to include all the commodities of 

cottonseed in the updated CSG 20C on the Dimilin® 2L label and a tolerance for residues 

on cottonseed CSG 20C at 0.2 ppm. 

 Conversion of the nut, tree, group 14 tolerance to the updated nut, tree, crop group (CG) 

14-12 on the Dimilin® 2L label and tolerances for residues on this CG at 0.2 ppm to 

harmonize with the Codex MRL tolerance. 

 Increase the egg and poultry fat tolerances from 0.05 ppm to 0.15 ppm to support the 

proposed diflubenzuron use on alfalfa. 

 Increase the poultry meat byproducts from 0.05 to 0.06 ppm to support the proposed 

diflubenzuron use on alfalfa. 

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The submitted labels are adequate. 

The nature of the residue in plants (primary and rotational) and livestock is adequately 

understood to support the requested new uses. The residues of concern in plants (primary and 

rotational) and livestock are diflubenzuron and its metabolites 4-chlorophenylurea (CPU) and 

PCA (4-chloroaniline). 

 

The previously submitted confined and field rotational crop studies are adequate to address 

rotational crop considerations for this action and support the proposed 30-day plantback interval 

(PBI) for food and feed crops. 

Adequate enforcement and data collection methods are available to determine the residues of 

diflubenzuron and its metabolites (CPU and PCA) in plants and livestock. 

FDA multi-residue method (MRM) testing data indicate that neither diflubenzuron, PCA, nor 

CPU are adequately recovered 

The number, geographic representation, and the employed use patterns of the alfalfa, carrot, 

peach, and plum field trial data are adequate and support the requested use patterns. The residue 

data were generated using a validated data collection method, and are supported by adequate 

storage stability data. The maximum combined residues of diflubenzuron, CPU and PCA in/on 

alfalfa forage/hay/seed, carrot, peach, and plum were as follows, respectively: 3.60/13.3/0.48 

ppm, 0.08 ppm, 0.48 ppm, and 0.23 ppm. 

 

No new field trial data were submitted to support expansion of the current uses to CSG 8-10B, 

CSG 20C and to support the conversion of CG 14 to 14-12. Since the requested 

expansions/conversion of the crop groups are for the identical formulation and use pattern, no 

new residue chemistry data, including processing studies, are required to support these requests. 

Maximum reasonable dietary burdens (MRDBs) for diflubenzuron were calculated based on the 

proposed/registered uses. A comparison of the updated dietary burdens with previously 

submitted and adequate ruminant and poultry feeding studies demonstrate that the current milk 

and ruminant tissue tolerance are adequate to cover the proposed/registered uses. However, egg 

and poultry tissue tolerances as indicated in Table 2.2.2 should be established. 

There are no issues with respect to international harmonization associated with this petition. 

The previously submitted processed food and feed study on prune (dried plums) is adequate. 

Based on the study diflubenzuron residues do not concentrate in/on prunes. 

2.0 Regulatory Recommendations 

Provided a revised section F (as noted in Section 2.2.2) and analytical standards for metabolite 

CPU and PCA (as noted in Section 5.1.4) are submitted, there are no residue chemistry 

considerations that would preclude granting the requested use on peach and plum SCGs, on 

carrots and regionally restricted use on alfalfa forage, hay, and seed; as well as the necessary 

tolerances, as listed in Section 2.2.2, required to support those uses. 

Additionally, HED has no objection to the proposed expansions/conversion of the following CG 

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and CSG: 

 Expansion of the proposed use of diflubenzuron on peach to include all members of the 

peach SG 12-12B. 

 Expansion of the proposed use of diflubenzuron on plum to include all members of the 

plum CSG 12-12C. 

 Expansion of the current use of diflubenzuron on pepper to include all commodities of 

pepper/eggplant CSG 8-10B. 

 Expansion of the current use of diflubenzuron on the Cotton, undelinted seed to include 

all the commodities of cottonseed CSG 20C. 

 Conversion of the nut, tree, group 14 tolerance to nut, tree, group 14-12. 

Lastly, IR-4 has proposed new/increased livestock tolerances. HED has concluded that the 

proposed tolerances are adequate to cover secondary residues in livestock. 

2.1 Data Deficiencies/Data Needs 

None 

2.2 Tolerance Considerations 

2.2.1 Enforcement Analytical Method 

Residue Chemistry Chapter of the Diflubenzuron RED (DP# 209032, S. Knizner, 3/15/1995) 

DP# D285141 (G. Kramer, 9/6/2002)

Adequate enforcement analytical methods are available for the enforcement of tolerances for 

residues of diflubenzuron and its metabolites in crop and livestock commodities. Three 

enforcement methods for diflubenzuron are published in PAM, Vol. II as Methods I, II, and III. 

Method I is a GC/ECD method that determines diflubenzuron in plants as derivatized PCA. 

Method II is a GC/ECD method that can separately determine residues of diflubenzuron, CPU 

and PCA in eggs, milk, and livestock tissues, each as derivatized PCA. Method III is an 

HPLC/UV method that determines diflubenzuron per se in eggs, milk, and livestock tissues. All 

three methods have undergone successful Agency validations. The Diflubenzuron RED stated 

that Methods I and II are the preferred enforcement methods because they are easier to perform, 

have less interference, and are more sensitive. 

In conjunction with PP#8F4925 on rice, a new analytical methodology for plant commodities 

was successfully validated by an independent laboratory as well as by Agency chemists at 

ACB/BEAD, and was forwarded to FDA for publication in PAM Vol. II as Roman Numeral 

Methods. These methods can separately determine residues of diflubenzuron by GC/ECD, CPU 

by GC/ECD, and PCA by GC/MS using an isotopically labeled internal standard and by 

summing the response of the two ions. The reported LOQ for diflubenzuron in/on rice grain, 

straw, and bran is 0.01 ppm, and is 0.05 ppm in/on rice hull. In rice straw, the LOQ for CPU is 

0.01 ppm and 0.005 ppm for PCA. 

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FDA multi-residue method (MRM) testing data indicate that neither diflubenzuron, PCA, nor 

CPU are adequately recovered 

2.2.2 Recommended Tolerances 

Tolerances are currently established under 40 CFR §180.377 comply with the HED Interim 

Guidance on Tolerance Expressions (S. Knizner, 5/27/09); therefore, no revisions are 

recommended to the residue definition. Table 2.2.2, below summarizes the recommended 

tolerance levels and commodity definitions required to support the proposed new and revised 

uses included in these petitions. 

IR-4 is requested to submit a revised section F for the following reasons, 

1) to remove the request for tolerance on plum, prune, dried. Based on a previously conducted 

processing study (MRID# 25252208) diflubenzuron residues are not found to concentrate on 

prunes (dried plum). Therefore, a separate tolerance for prunes is not required. 

 

2) to revise the tolerances for poultry egg, fat and meat byproducts. Based on the current dietary 

burden calculation, the anticipated residues in poultry fat, egg and meat byproducts are different 

than what was proposed. 

 

Table 2.2.2. Tolerance Summary for Diflubenzuron. 

Commodity Proposed Tolerance 

(ppm) 

HED-Recommended 

Tolerance (ppm) 

Comments 

(correct commodity definition) 

40 CFR §180.377(a)(1) Tolerance for residues. 

Cottonseed subgroup 20C 0.2 0.20 Significant figures. 

Established tolerance for cotton, 

undelinted seed can be removed from 

40CFR and replaced by this subgroup 

tolerance. 

Egg 0.15 0.07 Current tolerance level is 0.05 ppm; 

Increase to support the diflubenzuron 

uses on alfalfa.

Poultry, fat 0.15 0.10 Current tolerance level is 0.05 ppm; 

Increase to support the diflubenzuron 

uses on alfalfa. 

Poultry, meat byproducts 0.06 0.08 Current tolerance level is 0.05 ppm; 

Increase to support the diflubenzuron 

uses on alfalfa. 

40 CFR §180.377(a)(2) Tolerance for residues.

Carrot, roots 0.2 0.20 Significant figures. 

Peach subgroup 12-12B 0.5 0.50 Significant figures. 

Established tolerance (0.07 ppm) for 

fruit, stone, group 12, except cherry 

can be removed from 40CFR and 

replaced by this subgroup tolerance. 

Plum subgroup 12-12C 0.5 0.50 Significant figures. 

Established tolerance (0.07 ppm) for 

fruit, stone, group 12, except cherry 

can be removed from 40CFR and 

replaced by this subgroup tolerance 

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Table 2.2.2. Tolerance Summary for Diflubenzuron. 

Commodity Proposed Tolerance 

(ppm) 

HED-Recommended 

Tolerance (ppm) 

Comments 

(correct commodity definition) 

to harmonize with codex. 

Plum, prune, dried 0.5 -- A separate tolerance is not required. 

Diflubenzuron residues are not found 

to concentrate on prunes (dried 

plum). 

Nut, tree, group 14-12 0.2 0.20 Significant figures. 

Established tolerance for pistachio 

and nut, tree, group 14 can be 

removed from 40CFR and replaced 

by this subgroup tolerance to 

harmonize with codex. 

Pepper/Eggplant subgroup 

8-10B 

1.0 1.0 Established tolerance for pepper can 

be removed from 40CFR and 

replaced by this subgroup tolerance. 

40 CFR 7180.377(c) Tolerances with regional registrations. 

Alfalfa, forage 6 6.0 Significant figures. 

Alfalfa, hay 20 20 

Alfalfa, seed 0.9 0.90 Significant figures. 

2.2.3 Revisions to Petitioned-For Tolerances 

R-4 is requested to submit a revised section F to remove the request for tolerance on Plum, 

prune, dried and to revise the tolerance for poultry fat, meat byproduct as outlined in section 

2.2.2. Based on a previously conducted processing study (MRID# 25252208) diflubenzuron 

residues are not found to concentrate on prunes (dried plum) a tolerance for prunes is not 

required. In addition, HED is recommending a number of changes in the numerical expression of 

the tolerance values in order to conform to current HED policy on significant figures. 

2.2.4 International Harmonization 

The Codex Alimentarius has established maximum residue limits (MRLs), expressed in terms of 

diflubenzuron per se, for many commodities including: peach CSG 12-12B (0.5 ppm), plum 

CSG 12-12C (including prunes) (0.5 ppm), nut tree (0.2 ppm), for chili pepper (3 ppm), dried 

chili pepper (20 ppm), sweet pepper (0.7 ppm), and for eggs (0.05 ppm). There are no Canadian 

or Mexican MRLs currently established. The International Residue Limit (IRL) status sheet is 

included as Attachment 3 to this memorandum. 

The Agency is currently not harmonized with Codex with respect to the residue definition in 

plant and livestock commodities. Since the Codex MRL is based on the same use pattern and 

data that EPA would rely on, HED recommends an increase in the peach CSG 12-12B tolerance 

to 0.50 ppm, plum CSG 12-12C tolerance to 0.5 0 ppm, and nut, tree, group tolerance to 0.20 

ppm to harmonize with the Codex MRL levels. 

2.3 Label Recommendations 

None 

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3.0 Introduction 

Diflubenzuron, (N-[((4-chlorophenyl)amino)carbonyl]-2,6-difluorobenzimide), a member of the 

urea-derivative chemical family, is classified as an insect growth regulator and is used as both an 

acaricide and insecticide. It is currently registered in the U.S. for use as a chitin inhibitor, which 

promotes an inability of immature insects to synthesize chitin to form a hard exoskeleton 

prevents development from the immature to the juvenile and adult stages. The main agriculture 

pests targeted for control with diflubenzuron are twig borer, stink bug, grasshopper, beet 

armyworm, soybean looper, rust mite, artichoke plume moth, and peanuts root knot nematode. 

Tolerances for diflubenzuron, currently established under 40 CFR §180.377, range from 0.02-55 

ppm.

3.1 Chemical Identity 

The chemical structure and nomenclature of diflubenzuron and its metabolites is shown in Table 

3.1. 

Table.3.1. Diflubenzuron Nomenclature.

Compound

Common Name Diflubenzuron 

Trade and other Names Dimilin, Vigilante, Micromite, Adept 

IUPAC Name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS Name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS Registry Number 35367-38-5 

End-Use Products (EP) 2 lb/gal FlC formulation; DIMILIN® 2L (EPA Reg. No. 400-461); 

25% WP formulation; DIMILIN® 25W (EPA Reg. No. 400-465); 

80% G formulation; Micromite® 80WGS (EPA Reg. No. 400-

487); 

Regulated Metabolite

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite

Common Name 4-chloroaniline (PCA)

3.2 Physical/Chemical Characteristics 

Diflubenzuron is a white crystalline solid, the technical material is off-white to yellow crystals. 

Melting points of the technical material is 210-230°C, and the pure form of 230-232°C (both 

with decomposition). The compound is sparingly soluble in water. In polar solvent the solubility 

F

F O

N

H

O

N

H

Cl

O

N

H

Cl

2

NH

Cl

2NH

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is moderate to good depending on the degree of polarity. It is a non-volatile compound. The 

physicochemical properties of diflubenzuron are presented in Table 3.2. 

Table 3.2. Physicochemical Properties of Diflubenzuron.

Parameter Value Reference 

Melting range 230-232 °C http://www.arsusda.gov/acsl/services/pp

pH Not available db/textfiles/DIFLUBENZURON

Density Not available

Water solubility (25 °C) 0.08 ppm

Solvent solubility (25 °C) (ppm) 6.5 x 103 Acetone 

2 x 103 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105 Dimethylsulfoxide 

1 x 103 Methanol 

6 x 102 Dichloromethane 

Vapor pressure (25 °C) 1.2 x 10- 4 mPa

Dissociation constant, pKa Not available

Octanol/water partition coefficient, 

Log(KOW) 

3.89

UV/visible absorption spectrum Not available

3.3 Pesticide Use Pattern/Directions for Use (860.1200) 

Chemtura Corporation has submitted a label for Dimilin® 2L (EPA Reg No. 400-461) which 

includes proposed use directions for carrot, members of the pepper/eggplant CSG 8-10B, peach 

CSG 12-12B, plum CSG 12-12C, cotton seed CSG 20C, nut, tree group 14-12; and a regionally 

restricted use directions for alfalfa (forage, hay, and seed). The proposed new use patterns for 

are summarized in the table below. 

Table 3.3. Summary of Proposed Use Directions for Use of Diflubenzuron. 

Applic. 

Timing, Type, 

and Equip. 

Formulation 

[EPA Reg. 

No.] 

Applic. 

Rate 

(lb ai/A) 

Max. No. 

Applic. per 

Season 

Max. Seasonal 

Applic. Rate 

(lb ai/A) 

PHI 

(days) 

Use Directions and 

Limitations 

Alfalfa (forage, hay, and seed) 

Foliar by 

ground or air 

equipment. 

Dimilin® 

2L [400-

461] 

0.0325 3 0.0975 1 

 For use in the states 

West of the Mississippi 

River. Minimum interval 

between the applications 

is 14 day. 

Carrot 

Foliar by 

ground 

equipment. 

Dimilin® 

2L [400-

461] 

0.125 2 0.25 7 

 For use in CA. 

Minimum interval 

between the applications 

is 7 day. 

Peach Subgroup 12-12B 

Airblast by 

ground 

equipment. 

Dimilin® 

2L [400-

461] 

0.25 2 0.50 14 

 Minimum interval 

between the applications 

is 7 day. 

Plum Subgroup 12-12C 

Airblast by 

ground 

equipment. 

Dimilin® 

2L [400-

461] 

0.25 2 0.50 14 

 Minimum interval 

between the applications 

is 7 day. 

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Additionally, Chemtura requested following to include in the proposed label: 

 Crop group conversion of currently registered CG 14 commodities to commodities in CG 14-

12 on the Dimilin® 2L label. The proposed use pattern for CG 14-12 commodities is 

identical to that currently registered on these two labels for CG 14 commodities. 

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

relative to those proposed new uses. 

4.0 Metabolite/Degradate Residue Profile 

Summary of Plant Metabolism Studies (DP# 272978, G. Kramer, 4/3/2001) 

HED Metabolism Assessment Review Committee (MARC) Meetings of 2/20/2001 and 5/8/2001. 

Residues of Concern for Cancer Risk Assessment (DP# 272976, G. Kramer and G. Reddy, 5/31/2001) 

4.1 Summary of Plant Metabolism and Residues of Concern (860.1300) 

The qualitative nature of the residue in plants is adequately understood based on data from citrus, 

mushroom, rice, and soybean metabolism studies. The metabolism of diflubenzuron in crops 

tested is similar, and the radioactive components are also similar to those found in soil. The 

residues of concern for diflubenzuron for risk assessment and tolerance enforcement in plants 

and fungi, determined by MARC is diflubenzuron and its metabolites CPU and PCA. 

Conclusions. The nature of the residue in plants has been adequately addressed and no 

additional data are required. 

4.2 Summary of Livestock Metabolism and Residues of Concern (860.1300) 

HED Metabolism Assessment Review Committee (MARC) Meetings of 2/20/2001 and 5/8/2001. 

Residues of Concern for Cancer Risk Assessment (DP# 272976, G. Kramer and G. Reddy, 5/31/2001) 

The nature of the residue in livestock is adequately understood based on acceptable poultry and 

ruminant metabolism studies reflecting oral dosing. The MARC has concluded that the residues 

of concern in livestock for the purpose of risk assessment and enforcement are diflubenzuron and 

its metabolites PCA and CPU. 

Conclusions. The nature of the residue in livestock has been adequately addressed and no 

additional data are required. 

4.3 Summary of Confined Rotational Crops and Residues of Concern (860.l850) 

MRID 43274101 (DP# 205481, S. Knizner, 2/2/1995); G. Kramer DP#s 321623, 321625, and 321627, 9/14/2006 

Although, the available confined rotational crop study was inadequate to fully satisfy the 

860.1850 guideline, the nature of the residue in rotational crops is adequately understood for 

purposes of this petition. The residues of concern in rotational crops are parent diflubenzuron, 

CPU, and PCA. 

Conclusions: Although, available confined rotational crop study was not adequate, the nature of 

the residue in rotational crops has been adequately delineated. Additional confined rotational 

crop data are not required at this time. 

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5.0 Residue Profile 

5.1 Residue Analytical Methods (860.1340) 

5.1.1 Data Collection Methods 

493599501.der, 6/15/2015,S. Biswas (alfalfa) 

493599502.der 6/15/2015, S. Biswas (alfalfa) 

493599503.der 6/15/2015, S. Biswas (carrot) 

493599504.der 6/15/2015, S. Biswas (peach and plum) 

493599505.der 6/15/2015, S. Biswas (peach and plum) 

Alfalfa 

Registrant has submitted two sets of field trial studies for alfalfa. The original study (MRID 

#493599501) was conducted to analyze the parent diflubenzuron only. In this study Residues of 

diflubenzuron in/on alfalfa forage, hay and seed were quantified by LC/MS/MS using a method 

derived from “Diflubenzuron: Magnitude of the Residue in Small Grains” by Janine Rose, Ph.D., 

IR-4 Study 08024, PTRL Study 1129W, July 28, 2004. Method modifications did not negatively 

affect the performance of the method. 

Residues of diflubenzuron were extracted from alfalfa forage, hay, or seeds by repeatedly 

extracting with acetonitrile. The extract was repeatedly partitioned with hexane and the 

combined hexane partitions were discarded. The remaining acetonitrile extract was rotoevaporated to dryness and reconstituted with acetonitrile. The reconstituted acetonitrile extract 

was passed through a pre-conditioned C18-SPE cartridge for clean-up followed by additional 

clean-up using a Si-SPE cartridge. The solvent was evaporated and the residue was reconstituted 

in acetonitrile and water. Samples were analyzed by LC/MS/MS. 

Method validation and concurrent method recovery data were provided. Samples were fortified 

with diflubenzuron at 0.05-5.0 ppm. Recoveries were within the acceptable range of 70-120%. 

The fortification levels used in method validation and concurrent method recovery were adequate 

to bracket expected residue levels. The LOQ, determined as the lowest level of method 

validation (LLMV), was 0.050 ppm for diflubenzuron in alfalfa forage and seeds, and 0.50 ppm 

in alfalfa hay. The calculated limit of detection (LOD) was 0.025 ppm. 

A second study (493599502) was conducted according to the ChemSAC decision (5/30/2007) to 

analyze diflubenzuron, PCA, and CPU residues in alfalfa commodities and to estimate the PCA 

and CPU residues in the trials from the original study. In this study, residues of diflubenzuron, 

CPU, and PCA in/on alfalfa forage, hay and seed were quantified by LC/MS/MS using methods 

derived from the reference methods: “Diflubenzuron: Magnitude of the Residue in Small 

Grains.” Janine E. Rose, Ph.D., IR-4 Study 08024, PTRL Study 1129W, July 28, 2004, and 

“Dimilin 25W, Dimilin 80WG and Dimilin 2L in Almonds, Magnitude of the Residue Study,” 

Author: Janine E. Rose, Uniroyal Study No. RP-98003, September 13, 1999. 

For analysis of diflubenzuron and CPU, processed sample matrix was homogenized, centrifuged, 

and extracted three times with acetonitrile. The acetonitrile layers were collected and further 

diluted into the calibration standard range with purified regent water and/or 10:90 

acetonitrile:purified reagent water (v:v). If particles were present, the sample was centrifuged 

prior to analysis by LC/MS/MS. The calculated LODs for diflubenzuron residues on alfalfa 

forage, hay, and seed samples were 0.01428, 0.01726, and 0.01624 ppm, respectively. The 

calculated LODs for CPU residues on alfalfa forage, hay and seed samples were 0.00156, 

Page 13 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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0.00123 and 0.00152 ppm, respectively. The LLMV was 0.05 ppm for diflubenzuron and 0.005 

ppm for CPU on alfalfa forage, hay and seed. 

For PCA detection, processed sample matrix was fortified with the internal standard (13C6)4-

chloroaniline).The fortified sample was vortexed then allowed to settle with the cap off for five 

minutes. The sample was then extracted with 0.1 N hydrochloric acid solution (in purified regent 

water) and shaken at 60oC for 30 minutes, brought to room temperature in a cold water bath, then 

centrifuged. The supernatant was then filtered and the remaining pellet was extracted twice 

more. Both extractions were collected and taken to a final volume of 100 mL with 0.1N 

hydrochloric acid solution. The sample was further diluted into the calibration standard range 

with 10 mM ammonia formate solution (in purified reagent water). If particles were present, the 

sample was centrifuged at 13,000 rpm for five minutes prior to analysis by LC/MS/MS. 

The calculated LODs for PCA residues on alfalfa forage, hay and seed samples were 0.00128, 

0.00096 and 0.00098 ppm, respectively. The calculated LOQs for PCA residues on alfalfa 

forage, hay and seed were 0.00385, 0.00289 and 0.00294 ppm, respectively. The LLMV was 

0.005 ppm for PCA on alfalfa forage, hay and seed. 

The methods were validated both prior to and concurrently with field trial samples of alfalfa 

forage, hay and seed matrices fortified with diflubenzuron, CPU and PCA at 0.005-50 ppm. 

Recoveries were within the acceptable range of 70-120%. The fortification levels used in method 

validation and concurrent method recovery were adequate to bracket expected residue levels. 

Carrot 

Residues of diflubenzuron, CPU, and PCA in/on carrot were quantified by LC/MS/MS using 

methods derived from “Diflubenzuron: Magnitude of the Residue in Small Grains”, Janine E. 

Rose, Ph.D., Uniroyal Study No. 08024, PTRL Study No. 1129W, or “Dimilin 25W, Dimilin 

80WG, and Dimilin 2L in Almonds: Magnitude of Residue Study”, Janine E. Rose, Ph.D., 

Uniroyal Study No. RP-98003, September 13, 1999. 

For analysis of diflubenzuron and CPU, the sample was homogenized, centrifuged, and then 

extracted three times using acetonitrile as the extraction solvent. The acetonitrile layers were 

collected and taken to a final volume of 80.0 mL with acetonitrile. For 4-chorophenyl urea, the 

sample was dried using a gentle stream of nitrogen, vortexed for 30 seconds after the addition of 

an aliquot of 10:90 acetonitrile:purified reagent water (v:v) and sonicated for five minutes. The 

sample was further diluted into the calibration standard range with purified reagent water. If 

particles were present, the sample was centrifuged at 13,000 rpm for five minutes prior to 

analysis by LC/MS/MS. The calculated LOD were calculated to be 0.01040 ppm 

(diflubenzuron), 0.00128 ppm (CPU) in/on carrot raw agricultural commodity (RAC) samples. 

For PCA the processed sample matrix was fortified with the internal standard ([13C6]4-

chloroaniline) for analysis. The sample was vortexed then allowed to settle with the cap off for 

five minutes. Residues were extracted using 0.1N hydrochloric acid solution (in purified reagent 

water) and shaken at 60°C for 30 minutes, brought to room temperature in a cold water bath, 

then centrifuged. The supernatant was then filtered and the remaining pellet was extracted twice 

more. Both extractions were collected and taken to a final volume of 100 mL with 0.1N 

hydrochloric acid solution. Residues were analyzed by LC/MS/MS. The LOD were calculated to 

be 0.00294 ppm (PCA) in/on carrot RAC samples. 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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Method validation and concurrent method recovery data were provided. Samples were fortified 

with diflubenzuron, CPU and PCA at 0.005-0.50 ppm. Recoveries were within the acceptable 

range of 70-120%. The fortification levels used in method validation and concurrent method 

recovery were adequate to bracket expected residue levels. The LOQ, determined as the LLMV, 

for residues of diflubenzuron in/on carrot samples was 0.050 ppm and 0.005 ppm for CPU and 

PCA. 

Peach and Plum 

Two peach and plum field trials studies were submitted in conjunction of the current petition. 

Studies were conducted by the registrant in 2005 and IR-4 in 2009 growing seasons. In both 

studies, peach and plum samples were analyzed for residues of diflubenzuron, CPU, and PCA by 

using validated modified analytical methods derived from, “Dimilin 25W, Dimilin 80WG, and 

Dimilin 2L in Almonds: Magnitude of Residue Study,” Janine E. Rose, Ph.D., Uniroyal Study 

No. RP-98003. This data collection methods was modified during both studies. The method was 

adequately validated in conjunction with the field sample analyses. Method modifications did not 

negatively affect the performance of the method. 

In the 2005 field trials, the diflubenzuron method utilized reverse phase high pressure liquid 

chromatography (HPLC) as a separation technique. The CPU and PCA methods utilized 

capillary column gas chromatography (GC) as a separation technique. Samples analyzed for 

diflubenzuron were subjected to organic solvent extraction followed by solid phase extraction 

clean-up. Quantitation of diflubenzuron was by HPLC and the limit of quantitation (LOQ) was 

0.05 ppm. The CPU method involved organic solvent extraction followed by solid phase 

extraction clean-up. Quantitation was by GC with an electron capture detector (ECD). PCA 

residues in peaches were extracted with dilute HCl after spiking the samples with an internal 

standard of 13C-PCA. The acidic extract was made alkaline and then was extracted with hexane. 

The PCA was cleaned-up on a Florisil column and derivatized before quantitation by GC/Mass 

spectrometry (MS). 

The LOQs for diflubenzuron, CPU, and PCA were 0.05, 0.01, and 0.005 ppm respectively. 

In the 2009 study, for analysis of diflubenzuron and CPU, samples of peach and plum were 

homogenized, centrifuged, and extracted three times with acetonitrile. For CPU, subsamples of 

peach and plum were dried using a gentle stream of nitrogen, vortexed for 30 seconds after the 

addition of an aliquot of 10:90 acetonitrile:purified reagent water (v:v), and sonicated for five 

minutes. The diflubenzuron and CPU extracts were further diluted into the calibration standard 

range with purified reagent water. If particles were present, samples were centrifuged prior to 

analysis by LC/MS/MS. The LLMV for residues of diflubenzuron and CPU in/on peach and 

plum samples were 0.05 ppm and 0.005 ppm, respectively. 

For PCA, the processed sample matrix was fortified with the internal standard ([13C6]4-

chloroaniline) followed by vortexing then were extracted with 0.1N hydrochloric acid and 

shaken at 60 °C for 30 minutes, brought to room temperature in a cold water bath, then 

centrifuged. The supernatant was then filtered and the remaining pellet was extracted twice 

more with 0.1N hydrochloric acid, collecting each extraction and taken to a final volume of 

100mL with hydrochloric acid. The peach and plum samples were further diluted into the 

calibration standard range with 10 mM ammonium formate in purified reagent water. The 

calculated LOD for PCA residues in/on peaches and plums were 0.00158 and 0.00058 ppm 

respectively. The LLMV for residues of PCA in/on peach and plum samples was 0.005 ppm. 

Page 15 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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The methods were validated prior to sample analysis using control peach and plum samples 

fortified with diflubenzuron, CPU, or PCA at 0.005-0.5 ppm. Recoveries were within the 

acceptable range of 70-120%. 

Conclusions: The residue analytical methods used to generate alfalfa, carrot, peach and plum 

field trial data have been adequately validated and are acceptable for data collection purposes. 

5.1.2 Multi-Residue Methods (860.1360) 

PAM Vol. I, Appendix II 

DP# 194722, L. Edwards, 9/17/93: Transmission of MRM data for diflubenzuron to FDA. 

DP# 254273, J. Rowell, 12/15/1998: Transmission of MRM data for PCA and CPU to FDA 

The registrant has submitted Multiresidue testing data for diflubenzuron that HED has forwarded 

to the FDA. Diflubenzuron, per se, was not found to chromatograph by GC, thus, the FDA 

multi-residue method (MRM) will not adequately recover diflubenzuron. In addition, the results 

of Multiresidue Method testing of PCA and CPU have been submitted and forwarded to FDA. 

Neither PCA nor CPU was adequately recovered. 

Conclusions: FDA MRM testing data indicate that neither diflubenzuron, PCA, nor CPU are 

adequately recovered. 

5.1.3 Tolerance Enforcement Methods 

Refer to section 2.2.1. 

5.1.4 Submittal of Analytical Reference Standards (860.1650) 

An analytical standard for diflubenzuron is currently available in the National Pesticide 

Standards Repository and does not expire until 1/31/2017. However, analytical standard for 

metabolites CPU and PCA are expired and must be replaced. 

The analytical reference standards must be sent to the Analytical Chemistry Lab, which is 

located at Fort Meade. Send them to the attention of either Theresa Cole or Thuy Ngygen at the 

following address: 

USEPA 

National Pesticide Standards Repository/Analytical Chemistry Branch/OPP 

701 Mapes Road 

Fort George G. Meade, MD 20755 5350 

The extended zip code must be used or the mail will be returned. 

5.2 Storage Stability (860.1380) 

493599502.der 6/15/2015, S. Biswas (alfalfa) 

493599503.der 6/15/2015, S. Biswas (carrot) 

493599504.der 6/15/2015, S. Biswas (peach and plum) 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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The storage intervals and conditions of samples from the crop field trials studies submitted to 

support the field trials in this petition are summarized below. 

Alfalfa: 

A storage stability study was conducted concurrently with the alfalfa field trial study. Samples of 

alfalfa were fortified with diflubenzuron, CPU and PCA at 0.5 ppm and 0.05 ppm, and stored 

frozen. Residues of diflubenzuron and its metabolites were stable in/on alfalfa forage, hay and 

seeds stored frozen for up to 322 days, 294 days and 259 days respectively. 

The storage durations and conditions of samples from the crop field trials submitted to support 

these petitions are presented in Table 5.2.1. 

TABLE 5.2.1. Summary of Storage Conditions.

Matrix 

(RAC) 

Storage 

Temperature 

(°C) 

Actual Storage Duration 

(days) 

Interval of Demonstrated 

Storage Stability 

(days) 

Diflubenzuron 

Alfalfa Forage 

<-20 

322 Residues of diflubenzuron 

were stable when stored 

frozen in alfalfa forage, hay 

and seed for up to 306 days 

(10 months). 

Alfalafa Hay 294 

Alfalfa Seed 259 

CPU

Alfalfa Forage 

<-20 

322 Residues of CPU were 

stable when stored frozen in 

alfalfa forage, hay and seed 

for up to 307 days (10 

months). 

Alfalafa Hay 294 

Alfalfa Seed 259 

PCA 

Alfalfa Forage 

<-20 

322 Residues of PCA were 

stable when stored frozen in 

alfalfa forage, hay and seed 

for up to 301 days (10 

months). 

Alfalafa Hay 292 

Alfalfa Seed 256 

Carrot: 

A storage stability study was conducted concurrently in conjunction with the carrot field trial 

study. Samples of carrots were fortified with diflubenzuron, CPU and PCA at 0.5 ppm and 0.05 

ppm respectively, and stored frozen. Residues of diflubenzuron and its metabolite were stable 

in/on carrot samples stored frozen up to 1263 days (42 months). 

The storage durations and conditions of samples from the crop field trials submitted to support 

these petitions are presented in Table 5.2.2. 

 

TABLE 5.2.2. Summary of Storage Conditions.

Matrix (RAC) Storage Temperature 

(°C) 

Actual Storage 

Duration 

(days) 

Interval of 

Demonstrated Storage 

Stability (days) 

Diflubenzuron 

Carrot <-20 1248-1263 

Residues of 

diflubenzuron were 

stable when stored 

frozen in carrot for up to 

1263days (42 months). 

CPU 

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Carrot <-20 1248 

Residues of CPU were 

stable when stored 

frozen in carrot for up to 

1248 days (42 months). 

PCA 

Carrot <-20 1263 

Residues of PCA were 

stable when stored 

frozen in carrot for up to 

1263days (42 months). 

Peach and Plums: 

A storage stability study was conducted concurrently in conjunction with the peach and plum 

field trial study. Samples of peach and plum were fortified with diflubenzuron, CPU and PCA at 

0.5 ppm and 0.05 ppm respectively, and stored frozen. Residues of diflubenzuron and its 

metabolite were stable in/on peach and plum samples stored frozen up to 911 days (30 months). 

The storage durations and conditions of samples from the crop field trials submitted to support 

these petitions are presented in Table 5.2.3. 

TABLE 5.2.3. Summary of Storage Conditions.

Matrix (RAC) Storage 

Temperature (°C) 

Actual Storage Duration 

(days) 

Interval of 

Demonstrated Storage 

Stability (days) 

Diflubenzuron 

Peach (without pits) <-20 867 Residues of 

diflubenzuron were 

stable when stored 

frozen in peach/plum 

(including dried) for 

up to 875 days (29 

months). 

Plum (without pits) <-20 875 

 Dried Plum (without pits) <-20 

800 

CPU

Peach (without pits) <-20 867 Residues of CPU were 

stable when stored 

frozen in peach/plum 

(including dried) for 

up to 875 days (29 

months). 

Plum (without pits) <-20 875 

Dried Plum (without pits) <-20 

800 

PCA 

Peach (without pits) <-20 903 Residues of PCA were 

stable when stored 

frozen in peach/plum 

(including dried) for 

up to 911 days (30 

months). 

Plum (without pits) <-20 911 

Dried Plum (without pits) <-20 

841 

Conclusions. Adequate storage stability data are available to support the storage conditions and 

intervals for samples from the submitted field trials. 

5.3 Residue Data 

5.3.1 Crop Field Trials (860.1500) 

493599501.der, 6/15/15,S. Biswas (alfalfa) 

493599502.der 6/15/15, S. Biswas (alfalfa) 

493599503.der 6/15/15, S. Biswas (carrot) 

493599504.der 6/15/15, S. Biswas (peach and plum) 

493599505.der 6/15/15, S. Biswas (peach and plum) 

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Alfalfa: 

IR-4 conducted two sets of field trials in NAFTA Growing Zones for alfalfa (forage, hay, and 

seed) in 2004/05 and 2011 growing seasons. A total of twelve field trials were conducted in these 

two studies. The original study (MRID No. 493599501) was conducted to analyze the parent 

diflubenzuron only. The second study (MRID No. 493599502) was conducted at 1X and 3X of 

the proposed application rate according to the ChemSAC decision (Minutes of 5/30/2007 Chem 

SAC Meeting), and the ratio of the three compounds were used to estimate level of CPU and 

PCA in the trials from the original study. 

Nine alfalfa field trials were conducted in the United States during 2004 and 2005 growing 

seasons (MRID No. 493599501). Trials were conducted in NAFTA Growing Zones 8 (CO, 2 

trials), 10 (CA, 3 trials), and 11 (ID, WA, 4 trials). A table comparing the submitted number of 

trials and geographical locations of the field trial data to the requirements outlined in the OCSPP 

Harmonized Test Guidelines is included in Attachment 1. At each field site, Treatment (TRT) 02 

consisted of three applications and three forage and hay sample cuttings. One application was 

made 1 day before a sample cutting (the same interval was followed for the other two 

applications and sample cuttings). All TRT 02 applications targeted 0.0325 lb ai/A. TRT 03 

(conducted at five field sites) consisted of three or four (CO09) applications of 0.0325 lb ai/A at 

14 (±1) day re-treatment intervals (RTIs), with the last application 1 day before collection of 

seed samples. At field trial 08678.04-ID04, the second application was made 19 days after the 

first application. One pint per acre of emulsified vegetable or paraffinic crop oil was included to 

aid in canopy penetration and to minimize water evaporation in both treatments. At field trials 

ID04, WA09, CA02 and CO09, seed samples were not collected due to poor seed set. The preharvest interval (PHI) was 1 day for all trials (TRT 02 and 03). 

Harvested alfalfa forage, hay, and seed samples were analyzed by a validated data collection 

method as mentioned in section 5.1 (storage intervals were also validated)The limit of detection 

(LOD) for this method was 0.025 μg/mL and the limit of quantitation (LOQ) was 0.05 ppm in 

alfalfa forage and seed, and 0.50 ppm in alfalfa hay. 

Following three applications of diflubenzuron, three forage and hay sample cuttings, and a PHI 

of 1 day, the maximum residues of diflubenzuron for TRT 02 were 2.9 ppm and 9.1 ppm in 

alfalfa forage and alfalfa hay, respectively. Residues were found to increase from the first to the 

third cutting at trial site CO09. Therefore, the forage and hay samples from the last cutting were 

the only samples analyzed in other trials (except for the first forage cutting in the CO01 trial). 

The submitted field trials for alfalfa commodities reflect the proposed crop use pattern. 

Following three applications of diflubenzuron at 14 (±1) day intervals and a PHI of 1 day, the 

maximum residue of diflubenzuron in alfalfa seed for TRT 03 was 0.43 ppm. No quantifiable 

residues (>LOQ) of diflubenzuron were detected in untreated control alfalfa forage, seed, and 

hay samples from all field sites. A residue decline study was not conducted. Individual sample 

and average field trial residue values are shown Attachment 2. 

TABLE 5.3.1.1. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total 

Applic. Rate 

(lb ai/A) 

PHI 

(days) 

Diflubenzuron 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Alfalfa Forage2

0.10 1 

18 0.82 2.9 2.5 1.8 1.8 0.50 

Alfalfa Hay2 18 2.6 9.1 8.2 5.2 5.3 1.8 

Alfalfa Seed 10 0.056 0.43 0.43 0.18 0.23 0.15 1

HAFT = Highest Average Field Trial 

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2

Alfalfa forage and hay 3rd cutting 

IR-4 conducted three additional alfalfa (forage, hay, and seed) trials in 2011 growing season 

based on the May 30, 2007 ChemSAC recommendations. Trials were conducted at 1X and 3X of 

the proposed application rate to estimate the levels of CPU and PCA in the trials from original 

study. Trials were conducted in the United States encompassing NAFTA Growing Zones 10 

(CA; 1 trial) and 11 (ID and WA; 2 trials) during the 2011 growing season. A table comparing 

the submitted number of trials and geographical locations of the field trial data to the 

requirements outlined in the OCSPP Harmonized Test Guidelines is included in Attachment 1. 

At each trial location, diflubenzuron (Dimilin 2L) was applied 3-4 times to alfalfa fields as a 

broadcast foliar application to four treated plots. At the first treated plot at all sites, the 

application rate was 0.0314-0.0351 lb ai/A/application [Treatment (TRT) 02] for a total rate 

range of 0.0978 to 0.1290 lb ai/A per season (1X the label rate). At the second treated plot at all 

sites, the application rate ranged from 0.0934 to 0.0982 lb ai/A/ application (TRT 03) for a total 

rate range of 0.2896 to 0.3808 lb ai/A per season (3X the label rate). Three applications were 

made to the other two treated plots 12-15 days apart. The application rates ranged from 0.0317 to 

0.0339 lb ai/A per application for a total rate range of 0.0967 to 0.1010 lb ai/A per season for 

TRT04. The application rates ranged from 0.0940 to 0.1007 lb ai/A per application for a total 

rate range of 0.2891 to 0.2979 lb ai/A per season for TRT05. An adjuvant was added to the spray 

mixture for all applications, except at the ID17 field trial for TRT 02 and TRT 03. 

At all the field trials, forage and hay samples were harvested 1 day after each application to the 

TRT02 and TRT03 plots. Seed samples were harvested 1 day after the last application to the 

TRT04 and TRT05 plots. 

The harvested alfalfa forage, hay and seed samples were analyzed for residues of diflubenzuron, 

4-chlorophenylurea (CPU), and 4-chloroaniline (PCA) by a validated data collection method 

mentioned in section 5.1 (storage intervals were also validated). The lowest level of method 

validation (LLMV) for residues of diflubenzuron in/on alfalfa samples was 0.050 ppm and the 

LLMV for residues of CPU and PCA in/on alfalfa samples was 0.005 ppm. 

Individual sample and average field trial residue values are shown Attachment 2. 

Residues of diflubenzuron from the TRT02 plot ranged from <0.05-5.73 ppm and 2.9-15.6 ppm 

in forage and hay samples, respectively. Residues of diflubenzuron from the TRT03 plot ranged 

from <0.05-11.6 ppm and 7.5-45 ppm in forage and hay samples, respectively. Residues of 

diflubenzuron in seed samples ranged from <0.05-60.3 ppm and 0.36-2.04 ppm in TRT04 and 

TRT05 plots, respectively. 

Residues of CPU and PCA were <0.005 ppm for all forage seed samples. Residues of CPU in 

hay ranged from <0.005-0.105 ppm (TRT02) and <0.005-0.144 ppm (TRT03). Residues of PCA 

in hay were <0.005 ppm (TRT02) and <0.005-0.00664 ppm (TRT03). 

TABLE 5.3.1.2. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity Total Applic. Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues of Diflubenzuron, CPU and PCA 

(ppm)1

n Min. Max. HAFT2 Median Mean Std. Dev.

Alfalfa Forage 0.1 

1 6 

0.0600 5.74 3.60 1.56 1.98 1.94 

0.3-0.4 3.40 11.6 9.70 6.06 7.71 4.99 

Alfalfa Hay 0.1 4.36 15.7 13.3 4.92 6.86 3.38 

0.3-0.4 10.1 45.2 41.1 17.1 23.1 14.4 

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Alfalfa Seed 0.1 0.06 60.3 47.43 0.26 15.9 25.7 

0.3 0.09 2.05 1.58 0.41 0.700 0.760 1

Residue values were from the third cutting 

2

HAFT = Highest Average Field Trial. 

3

This mean residue value for alfalfa seed from one field site was determined to be an outlier and was not included in the tolerance calculation. 

In regards to the estimation of CPU and PCA residues in the original alfalfa study, please refer to 

the following tables in this section for these calculations based on the percentage of metabolites 

compared to the parent in the second alfalfa study. These data were used to calculate total 

residues used in the OECD calculator. 

 Table 5.3.1.3. Alfalfa Forage - Third Cutting (mean residues).

Trial Diflubenzuron1 4-chlorophenyl urea1 4-chloroaniline1 Total ppm1

.11-CA147 3.585 0.005 0.005 3.595 

.11-ID17 0.86 0.005 0.005 0.870 

.11-WA*33 1.495 0.005 0.005 1.505 

2

Mean % of parent: 0.35 0.35 

 Calculated values Calculated values Total ppm 

.04-CO09 1.96 0.007 0.007 1.974 

.04-ID04 2.54 0.009 0.009 2.558 

.04-WA09 1.572 0.006 0.006 1.583 

.05-CO01 2.182 0.008 0.008 2.197 

.04-CA100 1.892 0.007 0.007 1.905 

.05-CA01 1.15 0.004 0.004 1.158 

.05-CA02 2.316 0.008 0.008 2.332 

.05-ID01 1.548 0.005 0.005 1.559 

.05-WA01 0.892 0.003 0.003 0.898 

 

Alfalfa Hay - Third Cutting (mean residues)

Trial Diflubenzuron 4-chlorophenyl urea 4-chloroaniline Total ppm 

.11-CA147 13.2 0.082 0.005 13.287 

.11-ID17 4.655 0.005 0.005 4.665 

.11-WA*33 4.74 0.005 0.005 4.75 

Mean % of parent: 0.3 0.09 

 Calculated values Calculated values Total ppm 

.04-CO09 6.384 0.019 0.006 6.409 

.04-ID04 7.448 0.022 0.007 7.477 

.04-WA09 5.208 0.016 0.005 5.228 

.05-CO01 8.160 0.024 0.007 8.192 

.04-CA100 4.411 0.013 0.004 4.428 

.05-CA01 3.457 0.010 0.003 3.470 

.05-CA02 5.220 0.016 0.005 5.240 

.05-ID01 4.444 0.013 0.004 4.461 

.05-WA01 2.896 0.009 0.003 2.907 

1

Residue values were from the third cutting 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 22 of 43 

2

 % of parent= average of (ppm metabolite*100)/ppm parent 

Table 5.3.1.4. Alfalfa Seed (mean residues).

Trial Diflubenzuron 4-chlorophenyl urea 4-chloroaniline Total ppm 

.11-CA147 0.248 0.005 0.005 0.258 

.11-ID17 0.05 0.005 0.005 0.06 

.

2

11- WA*33 47. 4 0. 005 0. 005 *47. 41 1

Mean % of parent: 6 6 

 Calculated values Calculated values Total ppm 

.05-CA01 0.132 0.008 0.008 0.148 

.04-CA100 0.346 0.021 0.021 0.388 

.05-CO01 0.431 0.026 0.026 0.483 

.05-ID01 0.160 0.010 0.010 0.180 

.05-WA01 0.068 0.004 0.004 0.076 

1

 % of parent= average of (ppm metabolite*100)/ppm parent 2the residue value from trial *11WA*33 was excluded because it is considered as an outlier 

Conclusions: The number and geographic representation of the submitted field alfalfa samples 

are adequate to support the requested geographically restricted use in the states west of the 

Mississippi river. The residue data support the requested use pattern. 

Carrot: 

The IR-4 has submitted field trial data for use of diflubenzuron on carrot. Nine field trials were 

conducted in the United States during the 2008 growing season. Trials were conducted in 

NAFTA Growing Zones 10 (CA, 4 trials), 2 (GA, 2 trials), 5 (OH, 1 trial), 6 (TX, 1 trial), and 11 

(WA, 1 trial). A table comparing the submitted number of trials and geographical locations of the 

field trial data to the requirements outlined in the OCSPP Harmonized Test Guidelines is 

included in Attachment 1. Each trial site consisted of one untreated plot and one treated plot. At 

each trial location, two foliar applications of the test substance (Dimilin 2L) were made at 6-8 

days re-treatment interval (RTI) to the treated plots at rates of 0.119-0.129 lb ai/A per application 

for a total rate of 0.243-0.255 lb ai/A per season (1X the label rate). No adjuvant or additive was 

added to spray mixtures for any of the applications. Carrot RAC samples were harvested 6-7 

days after the last application. At the CA88 trial, additional duplicate samples were collected at 

3, 10, and 14 days after the last application. 

The harvested carrot RAC samples were analyzed for residues of diflubenzuron, 4-

chlorophenylurea (CPU), and 4-chloroaniline (PCA) by a validated data collection method 

mentioned in section 5.1 (storage intervals were also validated). The lowest level of method 

validation (LLMV) for residues of diflubenzuron in/on carrot samples was 0.050 ppm and 0.005 

ppm for CPU and PCA. 

Following two foliar applications of Dimilin 2L at 6-8 days RTI, combined residues of 

diflubenzuron, CPU, and PCA were <0.06-0.08 ppm. In the decline trial, combined residues 

were 0.06 ppm at pre-harvest intervals (PHIs) of 3, 7, 10 and 14 days. Individual sample and 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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average field trial residue values are shown Attachment 2. 

Table 5.3.1.5. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues (Diflubenzuron + CPU + PCA) [ppm] 

n Min. Max. HAFT1 Median Mean2 Std. Dev.

Carrot 0.243-0.255 

3 2 0.06 0.06 0.06 - - - 

6-7 18 0.06 0.08 0.07 0.06 0.06 0.004 

10 2 0.06 0.06 0.06 - - - 

14 2 0.06 0.06 0.06 - - - 1

HAFT = Highest Average Field Trial 

Conclusions: The number and geographic representation and residue data are adequate to support 

the requested use pattern. 

 

Peach and Plum: 

A total of 12 peach and 8 plum field trials were conducted in NAFTA growing zones during 

2005 and 2009 growing season. A table comparing the submitted number of trials and 

geographical locations of the field trial data to the requirements outlined in the OCSPP 

Harmonized Test Guidelines is included in Attachment 1. 

 In 2005, 5 field trials for peach and 3 field trials for plum were conducted in NAFTA Growing 

Zones 10 (CA, 3 trials), 1 (PA, 1 trial), 2 (GA, 1 trial), 6 (TX, 1 trial), 5 (MI, 1 trial), and 12 

(WA, 1 trial). 

At each trial location, which consisted of one untreated plot and one treated plot, two air-blast 

applications of the test substance (Dimilin 2L) were made at 14 days re-treatment interval (RTI) 

at rates of 0.243-0.259 lb ai/A per application (1X the label rate) to the treated plots. An 

adjuvant was added to each spray mixture. Peach and plum raw agricultural commodity (RAC) 

samples were harvested 14 days after the last application. 

The harvested peach and plum RAC samples were analyzed for residues of diflubenzuron, 4-

chlorophenylurea (CPU), and 4-chloroaniline (PCA) by a validated data collection method 

mentioned in section 5.1 (storage intervals were also validated). The LLMV for residues of 

diflubenzuron, CPU and PCA in/on peach and plum samples were 0.05 ppm, 0.01 ppm, and 

0.005 ppm, respectively. 

Individual sample and average field trial residue values are shown Attachment 2. 

Following two foliar applications of Dimilin 2L at rates of 0.243-0.259 lb ai/A per application 

and 14 days RTI, combined residues of diflubenzuron, CPU, and PCA were 0.080-0.44 ppm in 

peaches without pits and 0.080-0.23 ppm in plums without pits harvested at 14 days pre-harvest 

interval (PHI). 

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TABLE 5.3.1.6. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined (Diflubenzuron + CPU + CPA) 

(ppm) 

N Min. Max. HAFT1 Median Mean Std. Dev.

Peach 0.489-0.510 14 15 0.08 0.44 0.24 0.18 0.16 0.05 

Plum 9 0.08 0.23 0.19 0.17 0.20 0.10 1

HAFT = Highest Average Field Trial. 

In 2009, 7 field trials for peach and 5 field trials for plum were conducted in NAFTA Growing 

Zones 10 (CA, 6 trials), 2 (NC and NJ, 3 trials), 4 (AR, 1 trial), 5 (MI, 1 trial), and 11 (WA, 1 

trial). 

At each trial location, which consisted of one untreated plot and one treated plot, two air-blast 

applications of the test substance (Dimilin 2L) were made post bloom 13-15 days re-treatment 

interval (RTI) at rates of 0.235-0.259 lb ai/A per application (1X the label rate) to the treated 

plots. An adjuvant was added to each spray mixture. Peach and plum raw agricultural 

commodity (RAC) samples were harvested 10-16 days after the last application. At the CA41 

trial, duplicate samples were collected 0, 7 and 21 days after the last application. At the CA43 

trial, duplicate samples of treated and untreated plums harvested 13 days after the last application 

were collected after drying. 

The harvested peach and plum RAC samples were analyzed for residues of diflubenzuron, CPU, 

PCA by a validated data collection method mentioned in section 5.1 (storage intervals were also 

validated). The LLMV for residues of diflubenzuron in/on peach and plum samples was 0.05 

ppm and 0.005 ppm for CPU and PCA. 

Following two foliar applications of Dimilin 2L at 14 days RTI, combined residues of 

diflubenzuron, CPU and PCA were 0.060-0.48 ppm in peaches without pits harvested at 14-16 

days pre-harvest interval (PHI) and 0.060-0.12 ppm in plums without pits harvested at 10-14 

days PHI. In the decline trial, combined residues declined from 0.24 ppm at 0-day PHI to 0.08 

ppm at 21-days PHI. 

TABLE 5.3.1.7. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues (diflubenzuron, CPU and PCA) 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Peach 

0.50 

0 2 0.17 0.30 0.24 0.24 0.24 0.090 

7 2 0.13 0.16 0.14 0.14 0.14 0.020 

14-16 14 0.090 0.48 0.44 0.14 0.19 0.12 

21 2 0.060 0.090 0.080 0.080 0.080 0.020 

Plum 13-14 10 0.060 0.12 0.12 0.060 0.080 0.020 

Dried Plum 13 1 0.20 0.20 NA2 NA NA NA 1

HAFT = Highest Average Field Trial. 

2

NA = Not applicable

Conclusions: The representative commodities for the peach CSG 12-12B and plum CSG 12-12C 

are peach and plum respectively. The number and geographic representation of the submitted 

peach and plum samples are adequate to support the requested use of Dimilin® 2L on the 

commodities in CSGs 12-12B and 12-12C. 

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Pepper/Eggplant CSG 8-10B 

No new field trial data were submitted to support the requested expansion of the current use on 

pepper to the pepper/eggplant CSG 8-10B. 

Conclusions. The representative commodity for the pepper/eggplant CSG 8-10B is pepper. 

Since a pepper use is already on the label (Dimilin® 2L) and since the proposed application 

scenario for the CSG 8-10B is identical to the currently registered pepper use pattern, no new 

data are required to support the requested use on the CSG 8-10B. The newly requested use on 

CSG 8-10B commodities is considered adequately supported by the residue data previously 

submitted to establish the pepper use. 

Cottonseed CSG 20C 

No new field trial data were submitted to support the requested expansion of the current use on 

cotton to the pepper/eggplant CSG 20C. 

Conclusions: The representative commodity for the cottonseed CSG 20C is cotton. Since a 

cotton use is already on the label (Dimilin® 2L) and since the requested CSG 20C use pattern is 

identical to the currently registered cotton use pattern, no new data are required to support the 

requested use on the crop cottonseed CSG 20C. The newly requested use on crop cottonseed 

CSG 20C commodities is considered adequately supported by the residue data previously 

submitted to establish the cotton use.

Nut, tree, group 14-12 

No new field trial data were submitted to support the requested CG conversion from CG 14 to 

14-12 and to support the expansion of current use on the nut, tree, group 14 to the nut, tree, 

group 14-12. 

Conclusions: The representative commodities and data requirements for CG 14 are identical to 

those for CG 14-12. Since the CG 14 uses are already on the labels (Dimilin® 2L) and since the 

requested use pattern for CG14-12 is identical to the currently registered use pattern for CG14, 

no new data are required to support the requested use on the pome fruit CG 14-12. The newly 

requested use on CG 14-12 commodities is considered adequately supported by the residue data 

previously submitted to establish the CG 14 use. 

5.3.2 Field Rotational Crops (860.1900) 

MRID 44689703 (DP#s 244487, 251221, 251609, 253041, 253043; G. Kramer, 2/17/99) 

An acceptable limited field rotational crop study has been previously submitted. HED’s review 

of the study concluded that quantifiable residues of diflubenzuron, CPU, and PCA are unlikely to 

occur in rotated crops planted at least 30 days after being treated with diflubenzuron. Currently, a 

PBI of 30 day is established for the food and feed crops. 

Conclusions: The field rotational data and the current PBI of 30 day is adequate to support the 

proposed uses of diflubenzuron. The proposed label contains 30-day PBI for all food and feed 

crops. 

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5.3.3 Processed Food and Feed (860.1520) 

MRID 25252208 (DP# 277691; G. Kramer, 2/27/2002), (493599504.der x/x/15, S. Biswas (peach and plum) 

The previously submitted processed food and feed study on prune (dried plums) is adequate. 

Based on the study diflubenzuron residues do not concentrate in/on prunes. 

Additionally, based on the submitted data -combined residues of diflubenzuron, CPU and PCA 

in dried plums were 0.20 ppm (Table 5.3.3). 

 

TABLE 5.3.3. Summary of Residue Data from Crop Field Trials with Diflubenzuron (dried plum).

Commodity Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues (diflubenzuron, CPU and PCA) 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Dried Plum 13 1 0.20 0.20 NA2 NA NA NA 

5.3.4 Meat, Milk, Poultry, and Eggs (860.1480) 

There are ruminant and/or poultry feed items associated with the proposed uses of diflubenzuron 

on alfalfa (forage, hay, and seeds) and carrot. 

5.3.4.1 Dietary Burden 

Maximum Reasonable Dietary Burdens (MRDBs) 

Although there are many plausible ways of estimating the MRDBs for diflubenzuron to 

livestock, the calculation of dietary burdens, presented in Table 5.3.4.1, largely incorporates the 

feed items associated with the current petition. The MRDBs of diflubenzuron are 3.39 ppm for 

beef cattle, 19.34 ppm for dairy cattle, 1.05 ppm for poultry, and 1.0 ppm for hog. 

TABLE 5.3.4.1. Calculation of MRDBs. 

Crop Commodity Type1 Residue %Dry 

Matter2

%Diet Dietary Contribution3

ppm input ppm 

Beef Cattle 

Alfalfa Hay R 20 HR 89 15 3.37 

Wheat Grain CC 0.06 Median 89 20 0.01 

Rice Bran CC 0.02 Median 90 15 0.003 

Untreated feed NA NA NA NA NA 50 0 

Total NA NA NA NA NA 100 3.39 

Dairy Cattle 

Peanut Hay R 55 HR 85 15 9.71 

Grass Forage R 6 HR 25 30 7.20 

Carrot Culls CC 0.2 HR 12 10 0.17 

Wheat Grain CC 0.06 Median 89 20 0.01 

Rice Bran CC 0.02 Median 90 15 0.003 

Alfalfa Meal PC 20 HR 89 10 2.25 

Total NA NA NA NA NA 100 19.34 

Poultry 

Wheat Grain CC 0.06 Median 89 75 0.05 

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Alfalfa Meal PC 20 HR 89 5 1.00 

Untreated feed NA NA NA NA NA 20 0 

Total NA NA NA NA NA 100 1.05 

Swine 

Rice Bran CC 0.02 Median 90 10 0.002 

Alfalfa Meal PC 20 HR 89 5 1.00 

Untreated feed NA NA NA NA NA 85 0 

Total NA NA NA NA NA 100 1 

1

 R: Roughage; CC: Carbohydrate concentrate; PC: Protein concentrate. 2

 OCSPP 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 hog. 

5.3.4.2 Estimated Secondary Residues in Livestock 

Residue Chemistry Chapter of the Diflubenzuron Registration Standard (11/84) 

Residue Chemistry Chapter of the Diflubenzuron RED (DP# 209032, S. Knizner, 3/15/1995) 

No livestock feeding studies were submitted with this petition. Numerous diflubenzuron feeding 

studies have been reviewed previously by HED. Those that are the most relevant to the current 

petitions are discussed below. 

Ruminant: 

In one cattle feeding study, lactating cows were dosed orally twice a day with diflubenzuron at 

either 25 (1.3X) or 250 (13x) ppm in the diet for up to 28 consecutive days. Residues of 

diflubenzuron per se were nondetectable (<0.05 ppm) in milk from both feeding levels sampled 

following 1 to 28 days of dosing. Residues of diflubenzuron per se were also nondetectable 

(<0.05 ppm) in the fat, muscle, liver, and kidneys of cows sacrificed after 8, 18, and 28 days of 

dosing at 25 (1.3X) ppm. For cows sacrificed after dosing at 250 (13X) ppm for 8, 18, and 28 

days, residues of diflubenzuron per se were nondetectable (<0.05 ppm) in the muscle and kidney, 

0.06-0.08 ppm in fat, and 0.09-0.1 ppm in liver. 

 

In the third feeding study, four dairy calves were fed diflubenzuron at a rate of 2.8 mg ai/kg body 

weight for 4-5 months and two were sacrificed. Then three others were fed at 1 mg ai/kg body 

weight for another year and sacrificed. The 2.8 and 1.0 mg/kg doses were equivalent to 

approximately 180 (9X) and 65 (3X) ppm, respectively, in the diet. Following dosing at 180 ppm 

(5x), residues of diflubenzuron were 0.02 ppm in liver and kidney, 0.04-0.08 ppm in fat, and 

<0.02 ppm in muscle. Residues of diflubenzuron per se were nondetectable (<0.02 ppm) in 

tissues from livestock after dosing at 65 ppm (3X). 

Poultry: 

Acceptable data are also available for residues of diflubenzuron in eggs, meat, meat byproducts, 

and fat of poultry. The Residue Chemistry Chapter of the Diflubenzuron Registration Standard 

(11/84) and the Addendum to the Diflubenzuron Registration Standard (12/84) cited five feeding 

studies on poultry. In one study, laying hens were orally dosed via capsule for 1-28 consecutive 

days at 0.05 (0.05X), 0.5 (0.5x), and 5 (5X) ppm of [14C]diflubenzuron in the diet. Hens were 

sacrificed at 3- to 7-day intervals throughout the study. Residues of diflubenzuron per se were 

0.21 ppm in fat after dosing at 5 ppm (5X) for 7 days. After 24 days of dosing at 5 ppm (5X), 

residues of diflubenzuron per se were 0.05 ppm in muscle and kidney, 0.16 ppm in liver, and 

0.14 ppm in eggs. This feeding study encompasses the currently calculated dietary burden for 

livestock and is used to calculate the expected secondary residues in poultry fat, egg and liver. 

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In another study, Black Barred Rock-Rhode Island Red (BBR/RIR) and White Leghorn (WL) 

hens were given feed containing diflubenzuron at 10 ppm (10X) for 15 weeks. Residues of 

diflubenzuron per se plateaued in eggs after 2 weeks and remained constant at ~0.3-0.6 ppm for 

the remainder of the dosing period. Hens were sacrificed after a 3-day withdrawal period. For 

BBR/RIR hens, average residues of diflubenzuron were 1.17 ppm in fat, 0.12 ppm in liver, and 

nondetectable (<0.01 ppm) in muscle at the end of the dosing period. For WL hens, average 

residues of diflubenzuron were 1.85 ppm in fat, 0.45 ppm in liver, and nondetectable (<0.01 

ppm) in muscle at the end of the dosing period. 

Male Hubbard chickens in another study were dosed for 98 days with feed containing 

diflubenzuron at 2.5 and 250 ppm, five hens at each level. At the 2.5 ppm feeding level (2.4X), 

residues of diflubenzuron per se were 2.2-6.9 ppm in fat, 0.09-0.45 ppm in muscle and skin, and 

0.06-0.72 ppm in liver. At the 250 ppm feeding level (238X), residues of diflubenzuron were 

23-62 ppm in fat, 0.9-3.3 ppm in muscle and skin, and 0.8-3.8 ppm in liver. 

Expected secondary residues in fat, liver and egg are calculated based on the current dietary 

burden calculations. Summary of the calculations is presented in the table 5.3.4.2 

TABLE 5.3.4.2. Diflubenzuron Expected Secondary Residues in Meat and Milk 

Animal Matrix Residue 

Definition 

Dietary Burden 

(ppm) 

Anticipated 

Residue 

(ppm) 

Rounded 

MRL (ppm) 

Poultry Fat diflubenzuron 1.05 0.099 0.10 

Poultry 

Liver/poultry 

meat 

byproducts 

diflubenzuron 1.05 0.076 0.08 

Poultry egg diflubenzuron 1.05 0.066 0.07 

Conclusions: There are ruminant and/or poultry feed items associated with the proposed uses of 

diflubenzuron on alfalfa (forage, hay, and seed) and carrot. The calculated maximum theoretical 

dietary burdens (3.39 ppm for beef cattle, 19.34 ppm for dairy cattle, 1.05 ppm for poultry, and 

1.0 ppm for hog), resulting from the proposed/registered uses, are supported by previouslysubmitted livestock feeding studies. Based on the current dietary burden calculations, anticipated 

residues in poultry fat, liver and eggs are higher than the currently established tolerances. Based 

on the calculation, HED, recommends to establish tolerances of diflubenzuron in poultry fat, 

liver/poultry meat byproducts and egg at 0.10 ppm, 0.08 ppm and 0.07 respectively. 

5.3.5 Food Handling (860.1460) 

There are no proposed uses that are relevant to this guideline topic. 

5.3.6 Water, Fish, and Irrigated Crops (860.1400) 

There are no proposed uses that are relevant to this guideline topic. 

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6.0 Tolerance Derivation 

The Agency’s Organization for Economic Cooperation and Development (OECD) MRL 

calculator was used to determine appropriate tolerance levels for the combined residues of 

diflubenzuron and its metabolite for alfalfa (forage, hay and seed), carrot, peach CSG 12-12B, 

plum CSG 12-12B. The results from the spreadsheet calculator support the HED-recommended 

tolerances listed in Section 2.2.2. 

Attachments 

Attachment 1. Trial Number and Geographic Location Tables 

Attachment 2. Individual Sample and Average Field Trial Results 

Attachment 3. International Residue Limit Status sheet 

Attachment 4. OECD MRL Calculator Inputs and Results 

Attachment 1. Trial Number and Geographic Location Tables 

TABLE A.1.1. Trial Numbers and Geographical Locations. 

NAFTA Growing Zones 

Alfalfa 

Submitted Requested 

1 1 

3 1 

4 

5 6 

7 1 

8 2 

9 1 

10 4 1 

11 6 1 

Total1 12 12 

 

TABLE A.1.3. Trial Numbers and Geographical Locations. 

NAFTA Growing Zones Carrot 

Submitted Requested 

Canada US 

2 21 

3 1 

5 1 1 

6 1 1 

10 4 4 

11 1 1 

Total 9 8 1

Region 2 trials in this study were conducted in southern Georgia, near the border with Region 3. 

TABLE A.1.5. Trial Numbers and Geographical Locations. 

NAFTA 

Growing 

Zones 

Peach Plum 

Submitted Requested1

Submitted Requested 

Canada US Canada US 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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1 2 1 

1A 1 

2 4 4 

3 

4 1 1 

5 1 1 1 1 

5A 

5B 

6 1 1 

7 

7A 

8 

9 

10 2 4 5 5 

11 1 1 

12 1 1 

Total 12 12 8 8 

. 

Attachment 2. Individual Sample and Average Field Trial Results 

TABLE A.2.1. Alfalfa: Residue Data from Crop Field Trials with Diflubenzuron. 

Trial ID 

(City, State/Year) Zone Crop/Variety Commodity or Matrix 

Total 

Rate 

(lb ai/A) 

PHI 

(days) 

Diflubenzuron (ppm)1

1st cutting 2nd cutting 3rd cutting 

04-CO09 (Fort Collins, CO 

/2004)2 8 Alfalfa/ 

Focus Forage 0.0972 1 1.24, 1.97 1.580, 

1.924 2.25, 1.67 

04-ID04 (Kimberly, ID 

/2004) 11 Alfalfa/ Rampage Forage 0.1040 1 2.19, 2.89 

04-WA09 (Prosser, WA 

/2004) 11 Alfalfa/ Perfect A1 Forage 0.0956 1 1.67, 1.48 

05-CO01 (Fort Collins, CO 

/2005) 8 Alfalfa/ Focus Forage 0.1000 1 1.85, 1.43 2.31, 2.05 

04-CA100 (Holtville, CA/ 

2005) 10 Alfalfa/ Cibola Forage 0.0962 1 1.86, 1.93 

05-CA01 (Holtville, CA/ 

2005) 10 Alfalfa/ 

Cibola Forage 0.0989 1 - - 1.10, 1.20 

05-CA02 (Davis, CA/ 

2005) 10 Various 

varieties Forage 0.0996 1 - - 2.22, 2.42 

05-ID01 (Kimberly, ID/ 

2005) 11 DK 140 Forage 0.0953 1 - - 1.50, 1.59 

05-WA01 (Prosser, WA/ 

2005) 11 Alfalfa/ 

Perfect A1 Forage 0.0975 1 - - 0.820, 0.960

04-CO09 (Fort Collins, CO 

/2004) 8 Alfalfa/ Focus Hay 0.0972 1 - - 6.61, 6.16 

04-ID04 (Kimberly, ID 

/2004) 11 Alfalfa/ Rampage Hay 0.1043 1 - - 5.82, 9.07 

04-WA09 (Prosser, WA 

/2004) 11 Alfalfa/ Perfect A1 Hay 0.0956 1 - - 5.49, 4.93 

04-CA100 (Holtville, CA/ 

2005) 10 Alfalfa/ Cibola Hay 0.0962 1 - - 4.17, 4.65 

05-CA01 (Holtville, CA/ 

2005) 10 Alfalfa/ 

Cibola Hay 0.0989 1 - - 3.34, 3.58 

05-CO01 (Fort Collins, CO 

/2005) 8 Alfalfa/ 

Focus Hay 0.0972 1 - - 8.28, 8.04 

05-CA02 (Davis, CA/ 

2005) 10 

Various 

varieties per 

plot 

Hay 0.0996 1 - - 5.40, 5.04 

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Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

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05-ID01 (Kimberly, ID/ 

2005) 11 Alfalfa/DK 

140 Hay 0.0953 1 - - 4.34, 4.54 

05-WA01 (Prosser, WA/ 

2005) 11 Alfalfa/ 

Perfect A1 Hay 0.0975 1 - - 2.61, 3.18 

05-CA01 (Holtville, CA/ 

2005) 

10 Alfalfa/ 

Cibola Seed 0.0989 1 - - 0.19, 0.070

04-CA100 (Holtville, CA/ 

2005) 

10 Alfalfa/ 

Cibola Seed 0.0962 1 - - 0.270, 0.420

05-CO01 (Fort Collins, CO 

/2005) 

8 Alfalfa/ 

Focus Seed 0.0972 1 - - 0.430, 0.430

05-ID01 (Kimberly, ID/ 

2005) 

11 Alfalfa/DK 

140 Seed 0.0953 1 - - 0.160, 0.160

05-WA01 (Prosser, WA/ 

2005) 

11 Alfalfa/ 

Perfect A1 Seed 0.0975 1 - - 0.056, 0.079

1

Samples were not analyzed for the metabolites CPU, and PCA. 

2

Residues were found to increase from the first to the third cutting at trial site CO09. Therefore, the forage and hay samples from the third cutting 

were the only samples analyzed in the remaining trials (except for the first forage cutting in the 05-CO01 trial). 

TABLE A.2.2. Alfalfa: Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/ 

Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

TRT

# 

Total 

Rate 

(lb ai/A)

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

CPA 

(ppm) 

Combined 

Residues 

(ppm)1

CA147 

(Holtville, CA/ 

2011) 

10 Alfalfa/ 

CUF 101 Forage 

02 0.1290 1 

2.57 <0.005 <0.005 2.582

2.37 <0.005 <0.005 2.382

1.99 <0.005 <0.005 2.003

2.44 <0.005 <0.005 2.453

5.73 <0.005 <0.005 5.744

1.44 <0.005 <0.005 1.454

03 0.3808 1 

4.24 <0.005 <0.005 4.252

5.15 <0.005 <0.005 5.162

4.05 <0.005 <0.005 4.063

3.75 <0.005 <0.005 3.763

11.6 <0.005 <0.005 11.614

7.77 <0.005 <0.005 7.784

ID17 

(Kimberly, ID/ 

2011) 

11 Alfalfa/ 

Sundance Forage 

02 0.1016 1 

0.76 <0.005 <0.005 0.772

0.74 <0.005 <0.005 0.752

1.15 <0.005 <0.005 1.163

1.61 <0.005 <0.005 1.623

<0.05 <0.005 <0.005 0.064

1.67 <0.005 <0.005 1.684

03 0.2907 1 

1.53 <0.005 <0.005 1.542

1.95 <0.005 <0.005 1.962

2.66 <0.005 <0.005 2.673

2.31 <0.005 <0.005 2.323

3.39 <0.005 <0.005 3.404

3.57 <0.005 <0.005 3.584

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Forage 

02 0.0978 1 

<0.05 <0.005 <0.005 0.062

<0.05 <0.005 <0.005 0.062

0.67 <0.005 <0.005 0.683

1.09 <0.005 <0.005 1.103

1.22 <0.005 <0.005 1.234

1.77 <0.005 <0.005 1.784

03 0.2896 1 

<0.05 <0.005 <0.005 0.062

<0.05 <0.005 <0.005 0.062

3.18 <0.005 <0.005 3.193

4.40 <0.005 <0.005 4.413

4.92 <0.005 <0.005 4.934

6.05 <0.005 <0.005 6.064

CA147 

(Holtville, CA/ 10 Alfalfa/ CUF 101 Hay 02 0.1290 1 5.41 <0.005 <0.005 5.422

6.66 <0.005 <0.005 6.672

Page 31 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 32 of 43 

TABLE A.2.2. Alfalfa: Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/ 

Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

TRT

# 

Total 

Rate 

(lb ai/A)

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

CPA 

(ppm) 

Combined 

Residues 

(ppm)1

2011) 5.95 <0.005 <0.005 5.963

7.32 <0.005 <0.005 7.333

15.6 0.105 <0.005 15.714

10.8 0.0595 <0.005 10.864

03 0.3808 1 

13.5 <0.005 <0.005 13.512

13.0 <0.005 <0.005 13.012

9.49 <0.005 <0.005 9.503

11.5 <0.005 <0.005 11.513

45.0 0.144 <0.005 45.154

36.9 0.124 0.0056 37.034

ID17 

(Kimberly, ID/ 

2011) 

11 Alfalfa/ 

Sundance Hay 

02 0.1016 1 

5.15 <0.005 <0.005 5.162

4.03 <0.005 <0.005 4.042

5.58 <0.005 <0.005 5.593

5.92 <0.005 <0.005 5.933

4.71 <0.005 <0.005 4.724

4.60 <0.005 <0.005 4.614

03 0.2907 1 

15.5 <0.005 0.0066 15.512

10.9 <0.005 0.0054 10.912

12.0 <0.005 <0.005 12.013

12.3 <0.005 0.0053 12.313

10.1 <0.005 <0.005 10.114

12.3 <0.005 <0.005 12.314

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Hay 

02 0.0978 1 

2.90 <0.005 <0.005 2.912

4.12 <0.005 <0.005 4.132

3.83 <0.005 <0.005 3.843

3.79 0.0053 <0.005 3.803

4.35 <0.005 <0.005 4.364

5.13 <0.005 <0.005 5.144

03 0.2896 

1 11.00 <0.005 <0.005 11.012

7.50 <0.005 <0.005 7.512

19.10 0.0059 0.0052 19.113

13.90 0.0056 0.0057 13.913

18.60 0.0068 <0.005 18.614

15.60 <0.005 <0.005 15.614

CA147 

(Holtville, CA/ 

2011) 

10 Alfalfa/ 

CUF 101 Seed 

04 0.0967 1 0.23 <0.005 <0.005 0.24 

0.26 <0.005 <0.005 0.27 

05 0.2919 1 0.44 <0.005 <0.005 0.45 

0.36 <0.005 <0.005 0.37 

ID17 

(Kimberly, ID/ 

2011) 

11 Alfalfa/ 

Sundance Seed 

04 0.1010 1 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

05 0.2978 1 0.079 <0.005 <0.005 0.09 

0.108 <0.005 <0.005 0.12 

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Seed 

04 0.0969 1 60.3 <0.005 <0.005 60.31 

34.5 <0.005 <0.005 34.51 

05 0.2891 1 1.10 <0.005 <0.005 1.11 

2.04 <0.005 <0.005 2.05 1

For residues <0.05 and <0.005 ppm, values of 0.05 and 0.005 ppm, respectively, were used to calculate the sum of combined residues 2

First cutting. 3Second cutting. 4Third cutting. 

Page 32 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 33 of 43 

TABLE A.2.3 Carrot Residue Data from Carrot Field Trials with Diflubenzuron

Trial ID 

(City, State/ Year) Zone Crop/Variety Commodity or Matrix 

Total Rate 

(lb ai/A) 

PHI 

(days)

Diflubenzuron

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

 Combined 

Residues 

(ppm)1

CA87 (Holtville, 

CA/2008) 10 Carrot/ Danvers 126 Root 0.25 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA88 (Parlier, CA 

/2008) 10 Carrot/ Danvers 126 Root 0.253 

3 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

10 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

14 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA*89 (Salinas, CA 

/2008) 10 Carrot/ Danvers 126 Root 0.251 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA*90 (Salinas, CA 

/2008) 10 Carrot/ 

Danvers 126 Root 0.255 6 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

GA*04 (Tifton, GA 

/2008) 2 Carrot/ Chantenay Red Root 0.254 6 0.0676 <0.005 <0.005 0.08 

<0.05 <0.005 <0.005 0.06 

GA*05 (Tifton, GA 

/2008) 2 Carrot/ Danvers Root 0.254 6 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

OH*04 (Willard, OH 

/2008) 5 Carrot/ 

Maverick Root 0.243 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

TX*35 (Weslaco, TX 

/2008) 6 Carrot/ 

Nikki (Nantes) Root 0.250 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

WA*17 (Moxee, WA 

/2008) 11 Carrot/ Ya Ya 1 Root 0.247 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

`TABLE A.2.4. Peach and Plum Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/Year) Zone Crop/ Variety Matrix Total Rate

(lb ai/A) 

PHI 

(days)

Diflubenzuron

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

Combined 

Residues1

(ppm) 

AR05 (Clarksville, AR/ 

2009) 4 Peach/ Crest 

Haven 

Fruit 

without pit 0.494 16 0.10, 0.09 <0.005 <0.005 0.11, 0.10 

CA39 

(Parlier, CA/2009) 10 Peach/ June 

Flame 

Fruit 

without pit 0.503 14 0.12, 0.09 <0.005 <0.005 0.13, 0.10 

CA41 

(Parlier, CA/2009) 

10 Peach/ June 

Flame 

Fruit 

without pit 0.508 

0 0.16, 0.29 <0.005 <0.005 0.17, 0.30 

7 0.15, 0.12 <0.005 <0.005 0.16, 0.13 

14 0.08, 0.08 <0.005 <0.005 0.09, 0.09 

21 0.08, <0.05 <0.005 <0.005 0.09, 0.06 

MI17 

(Fennville, MI/2009) 5 Peach/ 

Redskin 

Fruit 

without pit 0.502 14 0.40, 0.47 <0.005 <0.005 0.41, 0.48 

NC07 

(Jackson Springs/2009) 2 Peach/ 

Contender 

Fruit 

without pit 0.504 16 0.13, 0.14 <0.005 <0.005 0.14, 0.15 

NJ04 

(Cream Ridge, NJ/2009) 2 Peach/ 

Loring 

Fruit 

without pit 0.510 15 0.09, 0.17 <0.005 <0.005 0.10, 0.18 

NJ05 

(Cream Ridge, NJ/2009) 2 Peach/ 

Suncrest 

Fruit 

without pit 0.499 14 0.26, 0.26 <0.005 <0.005 0.27, 0.27 

CA38 

(Gridley, CA/2009) 10 Plum/ 

French 

Fruit 

without pit 0.484 13 0.06, 0.09 <0.005 <0.005 0.070, 0.10 

CA40 

(Parlier, CA/2009) 10 Plum/ 

John W 

Fruit 

without pit 0.502 14 <0.05, <0.05 <0.005 <0.005 0.060, 0.060

CA42 

(Parlier, CA/2009) 10 Plum/Black 

Splendor 

Fruit 

without pit 0.505 14 <0.05, <0.05 <0.005 <0.005 0.060, 0.060

Page 33 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 34 of 43 

CA43 

(Gridley, CA/2009) 10 Plum/ 

French 

Fruit 

without pit 0.484 13 

0.11, 0.10 <0.005 <0.005 0.12, 0.11 

Dried Fruit 

without pit 0.19 <0.005 <0.005 0.20 

WA18 

(Wapato, WA/ 2009) 11 Plum/ 

Late 

Fruit 

without pit 0.499 10 0.05, 0.06 <0.005 <0.005 0.060, 0.070

1

Diflubenzuron, CPU and CPA residues were determined by Smithers Viscient Laboratory. For residues <0.05 and <0.005 ppm, values of 0.05 

and 0.005 were used to determined combined residues of diflubenzuron + CPU + PCA 

TABLE A.2.5. Peach and plum Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, 

State/Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

Total Rate 

(lb a.i./A) 

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

Combined 

Residues1

(ppm) 

KHG-05-101 

(Athens, GA/ 

2005) 

2 Peach/ 

Contender Fruit 0.504 14 

0.42 <0.01 <0.005 0.44 

0.17 <0.01 <0.005 0.18 

0.10 <0.01 <0.005 0.11 

RGC-05-201 

(Orefield, PA/ 

2005) 

1 

Peach/ 

Garnet 

Beauty 

Fruit 0.507 14 

0.13 <0.01 <0.005 0.14 

0.11 <0.01 <0.005 0.12 

0.27 <0.01 <0.005 0.28 

RDH-05-301 

(Sultana, CA/ 

2005) 

10 

Peach/ 

September 

Delight 

Fruit 0.496 14 

0.070 <0.01 <0.005 0.08 

0.20 <0.01 <0.005 0.22 

0.33 <0.01 <0.005 0.35 

CLS-05-401 

(Hughson, CA/ 

2005) 

10 Peach/ 

Fairtime Fruit 0.495 14 

0.25 <0.01 <0.005 0.26 

0.22 <0.01 <0.005 0.23 

0.15 <0.01 <0.005 0.17 

AWD-05-501 

(Waller, TX/ 

2005) 

6 Peach/ 

Texas Royal Fruit 0.510 14 

0.060 <0.01 <0.005 0.080 

0.080 <0.01 <0.005 0.10 

0.21 <0.01 <0.005 0.23 

JAC-05-601 

(Conklin, MI/ 

2005) 

5 Plum/ 

Stanley Fruit 0.490 14 

0.15 <0.01 <0.005 0.17 

0.16 <0.01 <0.005 0.17 

0.19 <0.01 <0.005 0.20 

CLS-05-402 

(Live Oak, CA/ 

2005) 

10 Plum/ 

French Fruit 0.499 14 

0.080 <0.01 <0.005 0.10 

0.10 <0.01 <0.005 0.12 

0.070 <0.01 <0.005 0.080 

SCO-05-701 

(Zillah, WA/ 

2005) 

12 Plum/ 

Italian Fruit 0.489 14 

0.12 <0.01 <0.005 0.14 

0.20 <0.01 0.0199 0.23 

0.18 <0.01 0.02 0.21 1For residues <0.01 and <0.005 ppm, values of 0.01 and 0.005 were used to calculate combined residues of diflubenzuron, CPU and PCA

Attachment 3. International Residue Limit Status Sheet 

International Residue Limits 

Diflubenzuron (PC Code 108201; Date of Request 6/16/2015) 

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition: 

US Canada Mexico2 Codex3

40 CFR §180.377: 

Plant: diflubenzuron (N -[[(4-

chlorophenyl)amino]carbonyl]-2,6-

difluorobenzamide) 

Livestock: diflubenzuron 

None Diflubenzuron (fatsoluble). 

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg) 

Page 34 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 35 of 43 

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition: 

US Canada Mexico2 Codex3

US Canada Mexico2 Codex3

Carrot, roots 0.20 

Peach subgroup 12-12B 0.50 0.5 peach, nectarine 

Plum subgroup 12-12C 0.50 0.5 plums (including 

prunes) 

Nut, tree, group 14-12 0.20 0.2 tree nuts 

Pepper/Eggplant 

subgroup 8-10B 

1.0 3 peppers, chili 

20 peppers, chili, dried 

0.7 peppers, sweet 

Carrot, roots 0.20 

Alfalfa, forage 6.0 

Alfalfa, hay 20 

Alfalfa, seed 0.90 

Cottonseed subgroup 

20C 

0.20 

Egg 0.07 0.05 (*) 

Poultry, fat 0.10 

Poultry, meat 

byproducts 

0.08 

Completed by: M. Negussie; 06/29/15 

1

 Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant. 

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes. 

3 * = absent at the limit of quantitation;

 

Page 35 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 36 of 43 

Attachment 4. OECD MRL Calculator Inputs and Results 

Diflubenzuron

Alfalfa Forage

PHI 1

3 applications of 0.0325 lb ai/A,last cutting

Residues (mg/kg)

3.595

0.870

1.505

1.974 Total number of data (n) 12

2.558 Percentage of censored data 0%

1.583 Number of non-censored data 12

2.197 Lowest residue 0.870

1.905 Highest residue 3.595

1.158 Median residue 1.744

2.332 Mean 1.845

1.559 Standard deviation (SD) 0.771

0.898 Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 3.595

- Mean + 4 SD 4.928

- CF x 3 Mean 5.534

Unrounded MRL 5.534

Rounded MRL 6

3 applications of 0.0325 lb ai/A,last cutting

Diflubenzuron

Alfalfa Forage

PHI 1

Reset file Select frame Ge

Page 36 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 37 of 43 

Diflubenzuron

Alfalfa hay

PHI 1

3 applications of 0.0325 lb ai/A,last cutting

Residues (mg/kg)

13.287

4.665

4.750

6.409 Total number of data (n) 12

7.477 Percentage of censored data 0%

5.228 Number of non-censored data 12

8.192 Lowest residue 2.907

4.428 Highest residue 13.287

3.470 Median residue 4.989

5.240 Mean 5.876

4.461 Standard deviation (SD) 2.786

2.907 Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 13.287

- Mean + 4 SD 17.021

- CF x 3 Mean 17.629

Unrounded MRL 17.629

Rounded MRL 20

3 applications of 0.0325 lb ai/A,last cutting

Diflubenzuron

Alfalfa hay

PHI 1

Reset file Select frame Genera

Page 37 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 38 of 43 

Diflubenzuron

Alfalfa seed

PHI 1

3 applications of 0.0325 lb ai/A

Residues (mg/kg)

0.258

0.060

0.148

0.388 Total number of data (n) 7

0.483 Percentage of censored data 0%

0.180 Number of non-censored data 7

0.070 Lowest residue 0.060

Highest residue 0.483

Median residue 0.180

Mean 0.227

Standard deviation (SD) 0.160

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.483

- Mean + 4 SD 0.866

- CF x 3 Mean 0.680

Unrounded MRL 0.866

Rounded MRL 0.9

 High uncertainty of MRL estimate.

[Small dataset]

3 applications of 0.0325 lb ai/A

Diflubenzuron

Alfalfa seed

PHI 1

Reset file Select frame Ge

Page 38 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 39 of 43 

Diflubenzuron

Carrot

PHI 7

2 applications of 0.125 lb ai/A

Residues (mg/kg)

0.060

0.060

0.060

0.060 Total number of data (n) 9

0.060 Percentage of censored data 0%

0.060 Number of non-censored data 9

0.070 Lowest residue 0.060

0.060 Highest residue 0.070

0.060 Median residue 0.060

Mean 0.061

Standard deviation (SD) 0.003

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.070

- Mean + 4 SD 0.074

- CF x 3 Mean 0.183

Unrounded MRL 0.183

Rounded MRL 0.2

2 applications of 0.125 lb ai/A

Diflubenzuron

Carrot

PHI 7

Reset file Select frame Ge

Page 39 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 40 of 43 

Diflubenzuron

Peach

PHI 14

2 applications of 0.25 lb ai/A

Residues (mg/kg)

0.105

0.115

0.090

0.445 Total number of data (n) 12

0.145 Percentage of censored data 0%

0.140 Number of non-censored data 12

0.270 Lowest residue 0.090

0.243 Highest residue 0.445

0.180 Median residue 0.163

0.217 Mean 0.192

0.220 Standard deviation (SD) 0.098

0.137 Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.445

- Mean + 4 SD 0.585

- CF x 3 Mean 0.577

Unrounded MRL 0.585

Rounded MRL 0.6

2 applications of 0.25 lb ai/A

Diflubenzuron

Peach

PHI 14

Reset file Select frame Ge

Page 40 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 41 of 43 

References: 

DP#: 261060 

Subject: PP# 8F4925. Diflubenzuron (Dimilin® 2L, EPA Reg #400-461) on Rice. Results of 

Petition Method Validation (PMV). Case 289260. Submission S571149. 

From: G. Kramer 

To: R. Kumar and M. Laws 

Dated: 9/6/2002 

MRID(s): 443993-03 & -06 

DP#: 272976 

Subject: Health Effects Division (HED) Metabolism Assessment Review Committee (MARC) 

Meetings of 2/20/01 & 5/8/01. Diflubenzuron. Residues of Concern for Cancer Risk 

Assessment. Chemical 108201. 

From: G. Kramer and G. Reddy 

To: Y. Donovan 

Dated: 5/31/2001 

MRID(s): None 

DP#: 272978 

Subject: Diflubenzuron (DimilinTM 2L, EPA Reg #400-461) in/on Pears. Evaluation of Residue 

Data and Analytical Methods. 

From: G. Kramer 

To: S. Brothers and R. Forrest 

Dated: 4/3/2001 

MRID(s): 451196-01 and -02 

Diflubenzuron

Plum

PHI 14

2 applications of 0.25 lb ai/A

Residues (mg/kg)

0.085

0.060

0.060

0.115 Total number of data (n) 8

0.065 Percentage of censored data 0%

0.180 Number of non-censored data 8

0.100 Lowest residue 0.060

0.193 Highest residue 0.193

Median residue 0.093

Mean 0.107

Standard deviation (SD) 0.053

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 0.193

- Mean + 4 SD 0.318

- CF x 3 Mean 0.322

Unrounded MRL 0.322

Rounded MRL 0.4

2 applications of 0.25 lb ai/A

Diflubenzuron

Plum

PHI 14

Reset file Select frame Ge

Page 41 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 42 of 43 

DP#: 254273 

Subject: Submission of Multiresidue Method (MRM) test information for updating PAM-I, 

Appendix II: 

From: J. Rowell 

To: B. McMahon 

Dated: 3/22/1999 

MRID(s): 44707401 

DP#: 254275 

Subject: PP# 8F4925. Multiresidue Method Testing of p-Chloroaniline and 4-Chlorophenylurea 

in Rice Grain and Soybeans. 

From: J. Rowell 

To: F. Griffith 

Dated: 3/22/1999 

MRID(s): 44707401 

DP#s: 253043, 253041, 244487, 251221 and 251609 

Subject: PP#8F4925. Diflubenzuron (Dimilin® 2L, EPA Reg #400-461) on Rice. 

Amendments of 8/19/98, 11/20/98, 12/3/98, 1/21/99, 1/27/99 & 2/3/99. 

Analytical Method for Metabolites, Revised Label, Additional Residue, Storage 

Stability and Rotational Crop Data. 

From: G. Kramer 

To: M. Johnson/A. Sibold 

Dated: 2/17/1999 

MRIDs 44577601, 44689701-02, 44699201, 44692701, 44692703, 4469500102, and 

44707401 

DP#: 240107 

Subject: PP#8F4925. Diflubenzuron (Dimilin® 2L, EPA Reg #400-461) on Rice. Evaluation of 

Residue Data and Analytical Methods. 

From: G. Kramer 

To: T. Levine 

Dated: 6/23/1998 

MRID(s): 44486401, 44399301 thru 44399306 

DP#: 209032 

Subject: Chemistry Chapters of the Reregistration Eligibility Document 

From: S. Knizner 

To: S. Jennings, K, Whitby, and L. Kutney 

Dated: 3/17/1995 

MRID(s): None 

DP#s: 205481 

Subject: Diflubenzuron. Confined Rotational Crop Study. 

From: S. Knizner 

To: S. Jennings 

Dated: 2/1/1995 

MRID(s): 43274101 

DP#s: D321623 

Subject: Diflubenzuron. IR-4’s Request To Register New Food/Feed Uses on 

Barley, Oats, Wheat, Brassica Leafy Greens (Crop Subgroup 5B), Turnip Greens, 

Eggplant, Okra, Peanut, and Pummelo. Summary of Analytical Chemistry and Residue 

Data. PP#s 5E6965, 5E6966, and 5E6967. 

Page 42 of 100
Diflubenzuron Summary of Analytical Chemistry and Residue Data D423328 

Page 43 of 43 

From: G. Kramer 

To: B. Madden/D. Rosenblatt 

Dated: 9/14/2006 

MRID(s): 43274101 

Page 43 of 100
"'! DiOubcnzuron/10820 l/Chcmtum Corporation/400 

~~ -~ ~ DACO 7.4.117.4.2/0PPTS 860.1500/0ECD llA 6.3.1. 6.J.2, 6.3.3 und 1111\ 8.3.1, 8.3.2, 8.3.3 

~ '· Crop Field Trial - Pcech nnd Plum 

Primary Evaluator 

Peer Reviewer 

Approved by 

STUDY REPORTS: 

Environmental Scientist, 

California Department )>l))esticidc Regulation 

~~ l<a-#p 

Theresa Ratto, Ph.D., 

Senior Enviro.nmental Scientist (Specialist), 

California Department of Pesticide Regulation 

D<lte: 3/10/2015 

Dale: 

~~te:6/l 5/2015 

Thurston G. Morton, Chemist ~"'( HED/RABIV (7509P) 

Snmitra 

HED/RABVI 

Bose 

(7509P) 

Biswas, Chemist ~~/b ,.~ ~ 

MRID No. 49399505 Roy W. Russell (2008) Dimilin 2L in Peaches and Plums: Magnitude of 

the Residue Study. Lab Project Number: GRL-I 2280, Study TD. 2005-005. Unpublished study 

prepared by Chemtura Corporation. 7 I 9 pages. 

EXECUTIVE SUMMARY: 

The Interregional Research Project No. 4 (IR-4) has submitted field trial data for dinubenzuron 

on peach and plum. Eight field trials were conducted in the United States during 2005 growing 

se'1so.n. Trials were conducted in North American Free Trade Agreement (NAFTA) Growing 

Zones I 0 (CA, 3 trinls), I (PA, l trial), 2 (GA, I trial), 6 (TX, I trial), -5 (Ml, l trial), nnd 12 

(WA, I trial). 

At each test location, which consisted or one untreated plot and one treated plot, two air-blast 

applications of the test substance (Dimilin 2L) were made at 14 days re-treatment intervul (RTI) 

at rates of 0.243-0.259 lb ni/ A per application Lo the treated plots. An adjuvanl was added to 

each spray mixture. Peach a11d plum raw agricultural commodity (RAC) samples were harvested 

14 days after the last application. 

The peach and plum samples were analyzed for residues of diflubenzuron, 4-chlorophcnylurea 

(CPU), and 4-chloroaniline (PCA) using modified methods derived from, "Oimilin 25W, Dimilin 

80\VG, and Dimilin 2L in Almonds: Mugnitude of Residue Study'', Jnnine E. Rose, Ph.D., 

Uniroyal Study No. RP-98003. The methods were adequately validated in conjunction with the 

field sample analyses. The lowest level of method va li di1tion (LLMV) for residues of 

diflubenzuron, CPU and PCA in/on peach and plum samples v.1erc 0.05 ppm, 0.01 ppm, and 

0.005 ppm, respectively. 

PMRA Submission No. /DP Barcodc 0423328 /Mill D No. 49399505 Pngc I of 10 

Page 44 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 2 of 10

Following two foliar applications of Dimilin 2L at rates of 0.243-0.259 lb ai/A per application 

and 14 days RTI, combined residues of diflubenzuron, CPU and PCA were 0.080-0.44 ppm in 

peaches without pits and 0.080-0.23 ppm in plums without pits harvested at 14 days pre-harvest 

interval (PHI). 

Samples of plum and peach were stored for up to 363 days before analysis. A freezer storage 

stability study was not conducted in conjunction with this study, however, a storage stability 

study for residues of diflubenzuron, CPU and PCA in/on peaches and plums was conducted in 

IR-4 Study Number 08644 (MRID No. 49399504). 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS: 

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. Minor deficiencies/deviations were noted in the study reports, but 

none had any significant impact on the studies or their results. 

The acceptability of this study for regulatory purposes is addressed in the forthcoming U.S. EPA 

Residue Chemistry Summary Document [DP Barcode Dxxxxxx]. 

COMPLIANCE:

 Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data 

Confidentiality statements were provided. This study meets current GLP Requirements of 40 

CFR Part 160, with the following deviations, which do not affect the conclusions presented in 

this report: 

1. Supporting data such as weather, soil characteristics records; test site history and cultural 

practices; and maintenance fertilizers and pesticide data were not collected in strict 

adherence to 40 CFR 160 guidelines. 

2. The scale used at CLS-05-402 for obtaining field sample weights was not maintained 

according to GLP standards. 

A. BACKGROUND INFORMATION

Diflubenzuron is an insecticide/acaricide (insect growth regulator) that behaves as a chitin 

inhibitor to suppress the growth of many leaf-eating larvae, mosquito larvae, aquatic midges, rust 

mite, boll weevil, and flies. Diflubenzuron was first registered in the United States in 1979 for 

use as an insecticide. The Agency issued a Registration Standard for diflubenzuron in 

September, 1985, (NTIS #PB86-176500). Diflubenzuron was also the subject of a Residue 

Chemistry Chapter dated 11/16/84, an Addendum to the Registration Standard dated 12/4/84, 

and a Reregistration Standard Update dated 6/21/91. The Reregistration Eligibility Decision 

(RED) for diflubenzuron was issued in August, 1997 (EPA 738-R-97-008). Tolerances for 

residues of diflubenzuron are established under 40 CFR §180.377 [US EPA Data Evaluation 

Page 45 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 3 of 10

Record (DER) 11/14/2006]. 

TABLE A.1. Test Compound Nomenclature.

Diflubenzuron 

H

N

O

H

N

O

F

F

Cl

Common name Diflubenzuron 

Company experimental name DU 112307 

IUPAC name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS # 35367-38-5 

End-use product/(EP) Dimilin 2L 

Regulated Metabolite 

O

N

H

Cl

2

NH

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite 

Cl

2NH

Common Name 4-chloroaniline (PCA) 

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

Melting point/range 210-230°C 

(US EPA DER, 11/14/2006) 

pH Not available 

Density Not available 

Water solubility (25°C) 0.08 mg/L 

Solvent solubility (25°C) (ppm) 

6.5 x 103 Acetone 

2 x 103

 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105 Dimethylsulfoxide 

1 x 103

 Methanol 

6 x 102

 Dichloromethane 

Vapor pressure at 25°C 1.2x10-4mPA (9.0x10-10 mmHg) 

Dissociation constant (pKa) Not available 

Octanol/water partition coefficient Log(KOW) 3.89 

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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 4 of 10

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

UV/visible absorption spectrum Not available 

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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 5 of 10

B. EXPERIMENTAL DESIGN

B.1. Study Site Information 

TABLE B.1.1 Trial Site Conditions.

Trial Identification (City, State/Year) 

Soil characteristics1

Type %OM pH CEC 

meq/g 

KHG-05-101 (Athens, GA/2005) Clay Loam 

RGC-05-201 (Orefield, PA/2005) Silt Loam 

RDH-05-301 (Sultana, CA/2005) Loam 

CLS-05-401 (Hughson, CA/2005) Sandy Loam 

AWD-05-501 (Waller, TX/2005) Loamy Sand 

JAC-05-601 (Conklin, MI/2005) Loam 

CLS-05-402 (Live Oak, CA/2005) Sandy Loam 

SCO-05-701 (Zillah, WA/2005) Silt Loam 1

Not reported. These parameters are optional except in cases where their value affects the use pattern for the chemical. 

The actual temperature recordings were within average historical values for the residue study 

period, except KHG-05-101 which had slightly below normal temperatures. The actual rainfall 

average was within the historical rainfall average, except at the KHG-05-101 site, which 

experienced above normal rainfall. Irrigation was used to supplement as needed. 

TABLE B.1.2. Study Use Pattern on Peach and Plum.

Location 

(City, State/Year) 

Trial ID 

EP1

Application Tank Mix/ 

Method/Timing Volume Adjuvants 

(GPA)2

Rate 

(lb a.i./A) 

RTI3

(days)

Total Rate 

(lb a.i./A) 

Peach Field Trials 

(Athens, GA/2005) 

KHG-05-101 

Dimilin 

2L 

1. Airblast Sprayer/ 

Beginning fruit coloration 94 0.253 - 

0.504 Peptoil 

2. Airblast Sprayer/ (COC) 

Continued fruit coloration 93 0.251 14 

(Orefield, PA/2005) 

RGC-05-201 

Dimilin 

2L 

1. Airblast Sprayer/Early blush 66 0.255 - 0.507 Destiny 

2. Airblast Sprayer/Firm ripe 66 0.252 14 (MSO) 

(Sultana, CA/2005) 

RDH-05-301 

Dimilin 

2L 

1. Airblast Sprayer/ 

Fruit about 90% final size 80 0.250 - 

0.496 Crop Oil 

2. Airblast Sprayer/ Concentrate 

Advanced fruit coloration 67 0.246 15 

(Hughson, CA/2005) 

CLS-05-401 

Dimilin 

2L 

1. Airblast Sprayer/ 

Fruit about 80% final size 75 0.247 - 

0.495 Crop Oil 

2. Airblast Sprayer/ Concentrate 

Fruit about 90% final size 76 0.248 14 

(Waller, TX/2005) 

AWD-05-501 

Dimilin 

2L 

1. Airblast Sprayer/ 

Fruit about 60% final size 61 0.259 - 

0.510 Crop Oil 

2. Airblast Sprayer/Fruit final Concentrate 

size, color change beginning 63 0.251 14 

Plum Field Trials 

(Conklin, MI/2005) 

JAC-05-601 

Dimilin 

2L 

1. Airblast Sprayer/ 

Early fruit coloration 72 0.249 - 

0.490 Crop Oil 

2. Airblast Sprayer/ Concentrate 

Advanced fruit coloration 73 0.250 14 

Page 48 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 6 of 10

TABLE B.1.2. Study Use Pattern on Peach and Plum.

Location 

(City, State/Year) 

Trial ID 

EP1

Application Tank Mix/ 

Method/Timing Volume Adjuvants 

(GPA)2

Rate 

(lb a.i./A) 

RTI3

(days)

Total Rate 

(lb a.i./A) 

(Live Oak, CA/2005) 

CLS-05-402 

Dimilin 

2L 

1. Airblast Sprayer/Fruit coloring 75 0.250 - 

0.499 Crop Oil 

Concentrate 2. Airblast Sprayer/ 

Advanced fruit coloration 75 0.249 14 

(Zillah, WA/2005) 

SCO-05-701 

Dimilin 

2L 

1. Airblast Sprayer/Green fruit 88 0.243 - 0.489 Omni Supreme

2. Airblast Sprayer/Green fruit 90 0.246 15 (Mineral Oil) 1

EP = End-use Product 

2

 Gallons per acre 

3

Retreatment Interval 

TABLE B.1.3. Trial Numbers and Geographical Locations. 

NAFTA 

Growing 

Zones 

Peach Plum 

Submitted Requested Submitted Requested 

Canada US Canada US 

1 1 

1A 

2 1 

3 

4 

5 1 

5A 

5B 

6 1 

7 

7A 

8 

9 

10 2 1 

11 

12 1 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total 5 3 

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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 7 of 10

B.2. Sample Handling and Preparation

Representative samples consisting of 24 individual peaches or plums were harvested 14 days 

after the last application. Peaches and plums were hand-picked or picked using a pole picker 

from several places on at least four individual trees, from the untreated and then the treated plots. 

Peaches and plums were halved and pits removed. Samples were placed on ice immediately and 

transferred to freezers within four hours of harvesting. Samples were maintained in frozen 

storage before, during, and after shipment to the analytical laboratory, until sample analysis. 

RAC peach and plum samples were kept in frozen storage at the field laboratories until shipment 

to the analytical laboratory via freezer truck. Each sample was individually homogenized with 

dry ice, using a Robot Coupe Vertical Batch Processor and placed in separate plastic bags. The 

dry ice was allowed to sublime before weighing and analysis. 

B.3. Analytical Methodology

Peach and Plum samples were analyzed for residues of diflubenzuron, CPU, and PCA by using 

validated modified analytical methods derived from, “Dimilin 25W, Dimilin 80WG, and Dimilin 

2L in Almonds: Magnitude of Residue Study”, Janine E. Rose, Ph.D., Uniroyal Study No. RP98003. The methods were adequately validated in conjunction with the field sample analyses. 

The diflubenzuron method utilized reverse phase high pressure liquid chromatography (HPLC) 

as a separation technique. The CPU and PCA methods utilized capillary column gas 

chromatography (GC) as a separation technique. Samples analyzed for diflubenzuron were 

subjected to organic solvent extraction followed by solid phase extraction clean-up. Quantitation 

was by HPLC and the limit of quantitation (LOQ) was 0.05 ppm. The CPU method involved 

organic solvent extraction followed by solid phase extraction clean-up. Quantitation was by GC 

with an electron capture detector (ECD) and the LOQ was 0.01 ppm. PCA residues in peaches 

were extracted with dilute HCl after spiking the samples with an internal standard of 13C-PCA. 

The acidic extract was made alkaline and then was extracted with hexane. The PCA was 

cleaned-up on a Florisil column and derivatized before quantitation by GC/Mass spectrometry 

(MS). The LOQ for PCA was 0.005 ppm. 

C. RESULTS AND DISCUSSION 

The provided analytical methods were adequate for data collection. Recovery data for control 

samples fortified with diflubenzuron, CPU, and PCA and analyzed both prior to, and 

concurrently with, field-treated samples are summarized in Table C.1. Fortification levels 

ranged from 0.005 to 0.5 ppm. Method validation recoveries were within the acceptable range of 

70% to 120% for diflubenzuron, CPU, and PCA on peach and plum. No quantifiable residues of 

diflubenzuron, CPU or PCA were detected in untreated control peach or plum samples. 

Following two foliar applications of Dimilin 2L at 14 days RTI, combined residues of 

diflubenzuron, CPU and PCA were 0.08-0.44 ppm in peaches and 0.08-0.23 ppm in plums 

harvested at 14 days PHI. Storage stability analysis was not conducted for this study (Table 

Page 50 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 8 of 10

C.2), but was done in IR-4 Study No. 08644 (MRID No. 49399504). 

TABLE C.1. Summary of Recoveries of Diflubenzuron, CPU and PCA from Peach and Plum.

Matrix Type of 

Recovery 

Spike level 

(ppm) 

Sample size 

(n) 

Recoveries 

(%) 

Mean ± Std Dev 

(%) 

Diflubenzuron 

Peach 

MV 0.05 7 89, 96, 103, 94, 95, 97, 88 95 ± 5 

0.07 3 95, 96, 95 95 ± 1 

0.10 3 89, 94, 93 92 ± 3 

CR 0.05 5 71, 92, 91, 92, 71 83 ± 11 

0.10 5 89, 79, 79, 82, 89 84 ± 5 

Plum 

MV 0.05 7 98, 91, 91, 90, 107, 98, 101 97 ± 6 

0.07 3 99, 102, 97 99 ± 3 

0.10 3 93, 99, 94 95 ± 3 

CR 0.05 2 94, 95 94 ± 1 

0.10 2 89, 88 88 ± 1 

CPU 

Peach 

MV 

0.01 6 73, 87, 88, 101, 86, 84 86 ± 9 

0.05 3 117, 98, 89 100 ± 4 

0.10 3 105, 99, 97 101 ± 14 

CR 0.01 2 118, 119 118 ± 1 

0.10 2 87, 86 86 ± 1 

Plum 

MV 

0.01 8 82, 108, 104, 98, 85, 81, 93, 85 92 ± 10 

0.05 3 109, 93, 104 102 ± 8 

0.10 3 85, 104, 97 95 ± 10 

CR 0.05 2 98, 98 98 ± 0 

0.10 2 77, 74 76 ± 2 

PCA 

Peach 

MV 

0.005 6 109, 106, 101, 97, 97, 100 102 ± 5 

0.05 3 104, 116, 94 104 ± 11 

0.10 3 101, 102, 101 101 ± 1 

CR 

0.005 1 127 - 

0.05 1 100 - 

0.10 2 97 - 

Plum 

MV 

0.005 6 93, 92, 97, 102, 112, 113 102 ± 9 

0.05 3 100, 105, 100 102 ± 3 

0.10 3 87, 105, 109 100 ± 12 

CR 0.005 2 110, 107 108 ± 2 

 0.10 2 94, 86 90 ± 6 

TABLE C.2. Summary of Storage Conditions. 

Matrix 

(RAC) 

Storage Temperature 

 (°C) 

Actual Storage Duration 

(days) 

Interval of Demonstrated 

Storage Stability1

(days) 

Peaches 217-304 

Plums 331-363 1

Storage stability analysis was not conducted for this study but was conducted in a subsequent study, IR4 Study No. 08664, MRID No. 49399504. 

Page 51 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 9 of 10

TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, 

State/Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

Total Rate 

(lb a.i./A) 

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

Combined 

Residues1

(ppm) 

KHG-05-101 

(Athens, GA/ 

2005) 

2 Peach/ 

Contender Fruit 0.504 14 

0.42 <0.01 <0.005 0.44 

0.17 <0.01 <0.005 0.18 

0.10 <0.01 <0.005 0.11 

RGC-05-201 

(Orefield, PA/ 

2005) 

1 

Peach/ 

Garnet 

Beauty 

Fruit 0.507 14 

0.13 <0.01 <0.005 0.14 

0.11 <0.01 <0.005 0.12 

0.27 <0.01 <0.005 0.28 

RDH-05-301 

(Sultana, CA/ 

2005) 

10 

Peach/ 

September 

Delight 

Fruit 0.496 14 

0.070 <0.01 <0.005 0.08 

0.20 <0.01 <0.005 0.22 

0.33 <0.01 <0.005 0.35 

CLS-05-401 

(Hughson, CA/ 

2005) 

10 Peach/ 

Fairtime Fruit 0.495 14 

0.25 <0.01 <0.005 0.26 

0.22 <0.01 <0.005 0.23 

0.15 <0.01 <0.005 0.17 

AWD-05-501 

(Waller, TX/ 

2005) 

6 Peach/ 

Texas Royal Fruit 0.510 14 

0.060 <0.01 <0.005 0.080 

0.080 <0.01 <0.005 0.10 

0.21 <0.01 <0.005 0.23 

JAC-05-601 

(Conklin, MI/ 

2005) 

5 Plum/ 

Stanley Fruit 0.490 14 

0.15 <0.01 <0.005 0.17 

0.16 <0.01 <0.005 0.17 

0.19 <0.01 <0.005 0.20 

CLS-05-402 

(Live Oak, CA/ 

2005) 

10 Plum/ 

French Fruit 0.499 14 

0.080 <0.01 <0.005 0.10 

0.10 <0.01 <0.005 0.12 

0.070 <0.01 <0.005 0.080 

SCO-05-701 

(Zillah, WA/ 

2005) 

12 Plum/ 

Italian Fruit 0.489 14 

0.12 <0.01 <0.005 0.14 

0.20 <0.01 0.0199 0.23 

0.18 <0.01 0.02 0.21 1For residues <0.01 and <0.005 ppm, values of 0.01 and 0.005 were used to calculate combined residues of diflubenzuron, CPU and PCA

TABLE C.4. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined (Diflubenzuron + CPU + CPA) 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Peach 0.489-0.510 14 15 0.08 0.44 0.24 0.18 0.16 0.05 

Plum 9 0.08 0.23 0.19 0.17 0.20 0.10 1

HAFT = Highest Average Field Trial. 

D. CONCLUSION 

The magnitude of the residue study of diflubenzuron on peach and plum was conducted 

consistent with standard agricultural practices according to proposed experimental designs. The 

weather conditions at each site were within normal parameters during the growing season, except 

for KHG-05-101 which had slightly below normal temperatures and above normal rainfall. 

The analytical methods used for determining diflubenzuron, CPU, and PCA in/on peach and 

plum were validated and adequate for data collection. Storage stability analysis was not 

conducted for this study, but was done in IR-4 Study Number 08644 (MRID No. 49399504). 

Following two foliar applications of Dimilin 2L at rates of 0.243-0.259 lb ai/A per application, 

with the use of an adjuvant, at 14 days RTI, combined residues of diflubenzuron, CPU and PCA 

were 0.08-0.44 ppm in peaches and 0.08-0.23 ppm in plums harvested at 14 days PHI. 

Page 52 of 100
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Crop Field Trial – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399505 Page 10 of 10

E. REFERENCES

US EPA DER (14-Sep-2006): MRID 46609501. Corley, J. (2005) Diflubenzuron: Magnitude of 

the Residue on Small Grain. Lab Project Number: 08024.02-PTR01. Unpublished study 

prepared by Interregional Research Project No. 4 (IR-4). 800 p. 

F. DOCUMENT TRACKING

RDI: T. Morton (6/20/2015) 

Petition Number(s): 4E8306 

DP Barcode(s): D423328 

PC Code: 108201 

Template Version June 2005.

Page 53 of 100
---·---- --------- ---- ----------------..-q 

r~"'I Difl1~bc11zuro~ I 082011c.h.em1ura Corpo~-ntion 400 .., 

:-.:=:.:iij a DACO 7.4.1/7 .4.2/0PP1 S 860.1500/0ECD I IA 6.3.1, 6.3.2, 6.3 . .i nnd III/\ S.J. I, 8.J.2, 8.3.3 Crop 

· ~ Field Triul/ Residue Decline - Alfalfa 

Primary Evaluntor 

Peer Reviewer 

Approved by 

J Jesus Leyva 

Environmental Scientist, 

e:r 1nent 

Theresa Ratto, Ph.D., 

Senior Envirqnmental Scientist (Specialist), 

California Department of Pesticide Regulation 

Thurston G. Morton, Chemist 

HED/RABIV (7509P) 

Date: 3/ J 0/2015 

Date: 

Su

HED/RABVI 

mitra Bose Biswas, 

(7509P) 

Chemist ~m., l., ..... 1~ '/3. ~ 

STUDY REPORTS: 

MRlD No. 49399501. William P. Barney and Kathryn Homa (2013) Dif1 ubenzuron: Magnitude 

of the Residue on Alfa! fa. Lab Project Number: 08678. Unpublished study prepared by The 

Interregional Research Project No. 4 (IR-4), 399 pages. 

EXECUTIVE SUMMARY: 

The IR-4 has submitted tie Id trial data for di flubcnzuron on alfalfa. Nine fieki'trials were 

. conducted in the United States during 2004 and 2005 growing seasons. Trials were conducted in 

North American free Trade Agreement (NA FT A) Growing Zones 8 (CO, 2 trials), 10 (CA, 3 

trials), and 11 (TD, \VA, 4 trials). At each field site, Treatment (TRT) 02 consisted of three 

applications m1d three forage and hay sample cu!1 ings. One application was made I day before a 

sample cutting (the same interval was followed for the other two applications and sample 

cuttings). All TRT 02 applications targeted 0.0325 lb ai/A TRT 03 (conducced at fiye field 

sites) consisted of three or four (C009) applications of 0.0325 lb ail A al 14 (± I) days rctreatment intervals (RTls) with the last application I day before collection of seed samples. At 

fieJcl trial 08678.04-!004, the second application was made 19 days ntler the first application. 

One pint per acre of emulsified vegetable or paraffinic crop oil was included to aid in canopy 

penetration and to minimize water evaporation in both treatments. Al field trials 1D04, WA09, 

CA02 and C009, seed samples were not collected due to poor seed set. The pre-harvest interval 

(Pl-II) was I clay for all trials (TRT 02 and 03). 

Harvested alfalfa forage, hay nnd seed samples were analyzed for dinubenzuron with liquid 

chromatography/tandem mass spectroscopy (LC/!VIS/MS) using a modified method derived from 

"Diflubcnzuron: Magnitude of the Residue on Small Grnin" IR-4 Study 08024, PTRL Study 

I I 229W, Jnnine E. Rose. The limit of detection (LOD)"for this method was 0.025 μg/mL and 

the limit of qunntitation (LOQ) was 0.05 ppm in alfn[fo forage and seed, ;.mcl 0.50 ppm in alfalfn 

hay. 

PMRA Submission No. /DP Bnrcode 0423328 /MRID No. 4939950 I · Page I of 11 

Page 54 of 100
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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 Crop 

Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 2 of 11

Following three applications of diflubenzuron, three forage and hay sample cuttings, and a PHI 

of 1 day, the maximum residues of diflubenzuron for TRT 02 were 2.9 ppm and 9.1 ppm in 

alfalfa forage and alfalfa hay, respectively. Residues were found to increase from the first to the 

third cutting at trial site CO09. Therefore, the forage and hay samples from the last cutting were 

the only samples analyzed in other trials (except for the first forage cutting in the CO01 trial). 

Following three applications of diflubenzuron at 14 (±1) day intervals and a PHI of 1 day, the 

maximum residue of diflubenzuron in alfalfa seed for TRT 03 was 0.43 ppm. No quantifiable 

residues (>LOQ) of diflubenzuron were detected in untreated control alfalfa forage, seed, and 

hay samples from all field sites. A residue decline study was not conducted. 

Storage stability analysis was not conducted for this study, but was done in IR-4 Study Number 

B8678 (MRID No. 49399502). 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS: 

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document [DP Barcode Dxxxxxx]. 

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. This study meets current GLP Requirements of 40 CFR Part 160, 

with the following deviations, which do not affect the conclusions presented in this report. 

1. Supporting field data such as weather/irrigation, soil characterization, test site history, 

cultural practices, maintenance fertilizer and pesticide data were not collected in 

adherence to Good Laboratory Practice Standards at all field sites. 

2. Data for pH measurements of carrier water were not collected in adherence to Good 

Laboratory Practice Standards at all field sites except for 08678.04-WA09 and 08678.05-

WA01. 

3. Sample weights and scale calibration data were not collected in adherence to Good 

Laboratory Practice Standards at the 08678.04-ID04, 08678.04-CA100, 08678.05-CA01, 

08678.05-CA02 and 0678.05-ID01 field sites. 

4. Equipment maintenance records were not recorded in adherence to Good Laboratory 

Practice Standards at all field sites except for 08678.05-CO01, 08678.05-WA01 and 

08678.05-WA09. 

5. In the field notebook for the 08678.04-WA09 trial site, late entries, in part 7, pp.40, 41, 

and 43, scale calibrations, were not entered promptly as specified in the GLP standards 

Page 55 of 100
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Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 3 of 11

160.130(e). 

6. The GPS receiver used at the 08678.04-CO09 field site was not maintained in adherence 

to Good Laboratory Practice Standards. 

7. At the 08678.05-CA02 field site, although percent moisture was determined for hay 

samples using a formula, the numbers used in the formula were not recorded. 

8. The moisture meter used at the 08678.05-ID01 field site was not maintained in adherence 

to Good Laboratory Practice Standards. 

9. The test substance was characterized by Crompton Co. (now Chemtura Corporation), 

Guelph, Ontario, Canada. Therefore, the test substance was not characterized in 

accordance with 160.135(a) (b), but was characterized in accordance with OECD 

guidelines, which are accepted by EPA in a Memorandum of Understanding. 

A. BACKGROUND INFORMATION

Diflubenzuron is an insecticide/acaricide (insect growth regulator) that behaves as a chitin 

inhibitor to suppress the growth of many leaf-eating larvae, mosquito larvae, aquatic midges, rust 

mite, boll weevil, and flies. Diflubenzuron was first registered in the United States in 1979 for 

use as an insecticide. The Agency issued a Registration Standard for diflubenzuron in 

September, 1985, (NTIS #PB86-176500). Diflubenzuron was also the subject of a Residue 

Chemistry Chapter dated 11/16/84, an Addendum to the Registration Standard dated 12/4/84, 

and a Reregistration Standard Update dated 6/21/91. The Reregistration Eligibility Decision 

(RED) for diflubenzuron was issued in August, 1997 (EPA 738-R-97-008). Tolerances for 

residues of diflubenzuron are established under 40 CFR §180.377 [US EPA Data Evaluation 

Record (DER), 11/14/2006]. 

TABLE A.1. Test Compound Nomenclature.

Diflubenzuron 

H

N

O

H

N

O

F

F

Cl

Common name Diflubenzuron 

Company experimental name DU 112307 

IUPAC name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS # 35367-38-5 

End-use product/(EP) 2 lb/gal FlC formulation; Dimilin 2L (EPA Reg. No. 400-461) 

Regulated Metabolite 

O

N

H

Cl

2NH

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Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 4 of 11

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite 

Cl

2NH

Common Name 4-chloroaniline (PCA) 

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

Melting point/range 230-232°C 

(US EPA DER, 11/14/2006) 

pH Not availabel 

Density (22°C) Not available 

Water solubility (25°C) 0.08 ppm 

Solvent solubility (ppm at 25°C) 

6.5 x 103 Acetone 

2 x 103

 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105 Dimethylsulfoxide 

1 x 103

 Methanol 

6 x 102

 Dichloromethane 

Vapour pressure at 25°C 1.2x10-4mPA (9.0x10-10 mmHg) 

Dissociation constant (pKa) Not available 

Octanol/water partition coefficient Log(KOW) 3.89 

UV/visible absorption spectrum Not available 

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 Crop 

Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 5 of 11

B. EXPERIMENTAL DESIGN

B.1. Study Site Information 

TABLE B.1.1 Trial Site Conditions.

Trial Identification (City, State/Year) 

Soil characteristics1

Type %OM pH CEC 

meq/g 

04-ID04 (Kimberly, ID/2004) Silt Loam 1.51 8.2 NR 

04-CA100 (Holtville, CA/2005) Silty Clay Loam 0.70 7.8 NR 

05-CA01 (Holtville, CA/2005) Silty Clay Loam 0.70 7.8 NR 

05-CO01 (Fort Collins, CO/2005) Clay Loam 2.6 7.5 22-28 

04-WA09 (Prosser, WA/2004) Silty Loam 1.28 7.8 14.4 

04-CO09 (Fort Collins, CO/2004) Clay Loam 2.0 7.7 NR 

05-CA02 (Davis, CA/2005) Loam 1.33 7.0 27.4 

05-WA01 (Prosser, WA/2005) TRT 02 Silt Loam 1.28 7.8 14.4 

05-WA01 (Touchet, WA/2005) TRT 03 Silt Loam NR2 6.6-7.8 5-10 

05-ID01 (Kimberly, ID/2005) TRT 02 Silt Loam 1.55 8.1 14.1 

05-ID01 (Kimberly, ID/2005) TRT 03 Silt Loam 1.9 8.1 18.7 1

OM = Organic matter, CEC = Cation-exchange capacity. These parameters are optional except in cases where their value affects the use pattern 

for the chemical. 

2

Not Reported 

The actual temperature recordings were within average historical values for the residue study 

period, except for cooler temperature early in the growing season at the 08678.04-CA100 field 

trial. The actual rainfall average was within the historical rainfall average, except for heavy rain 

and small hail at the 08678.04-CO09 field trial site, and a few rain events, which were not 

normal, in early March at the 08678.04-CA100 field trial site. Irrigation was used to supplement 

as needed. 

TABLE B.1.2 Study Use Pattern.

Location 

(City, 

State/Year) 

Trial ID 

EP1

Application 

Tank Mix/ 

Method/Timing Adjuvants Volume

GPA2

Rate 

(lb ai/A) RTI3

(days)

Total Rate 

(lb ai/A) 

TRT02 

(Kimberly, ID/ 

2004) 04-ID04 

Dimilin 

2L 

1. Broadcast/Early Bloom 26 0.0354 - 

2. Broadcast/Early Bloom 25 0.0345 51 0.1043 Mor-Act 

3. Broadcast/Early Bloom 25 0.0344 54 

(Holtville, CA/ 

2005) 04-CA100 

Dimilin 

2L 

1. Broadcast/5% Open Bloom 28 0.0341 - 

0.0996 

Amigo Vegetable 

Oil Surfactant 

(93% Vegetable Oil)

2. Broadcast/2% Open Bloom 27 0.0331 21 

3. Broadcast/5% Open Bloom 28 0.0324 23 

(Holtville, CA/ 

2005) 05-CA01 

Dimilin 

2L 

1. Broadcast/5% Open Bloom 29 0.0343 - 

0.0989 

Amigo Vegetable 

Oil Surfactant 

(93% Vegetable Oil)

2. Broadcast/2-3% Open Bloom 27 0.0324 21 

3. Broadcast/5% Open Bloom 28 0.0322 22 

(Fort Collins, 

CO/ 2005) 05-

CO01 

Dimilin 

2L 

1. Broadcast/ 

Vegetative-Late Bud 26 0.0335 - 

0.1000 Clean Crop Oil 

2. Broadcast/Early Bloom 25 0.0326 53 Concentrate 

3. Broadcast/Early Bloom 26 0.0339 35 

(Prosser, WA/ 

2004) 04-WA09 

Dimilin 

2L 

1. Broadcast/ Vegetative 23 0.0316 - 

0.0956 

Lilly Miller 

Superior Type 

Spray Oil 

2. Broadcast/Vegetative 26 0.0319 40 

3. Broadcast/Vegetative 26 0.0321 44 

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Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 6 of 11

TABLE B.1.2 Study Use Pattern.

Location 

(City, 

State/Year) 

Trial ID 

EP1

Application 

Tank Mix/ 

Method/Timing Adjuvants Volume

GPA2

Rate 

(lb ai/A) RTI3

(days)

Total Rate 

(lb ai/A) 

(Fort Collins, 

CO /2004) 04-

CO09 

Dimilin 

2L 

1. Broadcast/ 

Late-Bud/Early Bloom 

25 0.0321 - 

0.0972 PHT Crop Oil 

2. Broadcast/Early Bloom 25 0.0322 61 Concentrate 

3. Broadcast/Early Bloom 25 0.0329 37 

(Davis, CA/ 

2005) 05-CA02 

Dimilin 

2L 

1. Broadcast/ Vegetative 28 0.0332 - 

2. Broadcast/Vegetative 28 0.0333 34 0.0996 Herbimax 

3. Broadcast/Vegetative 28 0.0331 43 

(Prosser, WA/ 

2005) 05-WA01 

Dimilin 

2L 

1. Broadcast/Vegetative 21 0.0320 - 

0.0976 

Lilly Miller 

Superior Type 

Spray Oil 

2. Broadcast/Vegetative 26 0.0324 42 

3. Broadcast/Vegetative 27 0.0332 35 

(Kimberly, ID/ 

2005) 05-ID01 

Dimilin 

2L 

1. Broadcast/Early Bloom 25 0.0322 - 

2. Broadcast/ Early Bloom 25 0.0318 35 0.0962 Mor-Act 

3. Broadcast/Bloom 25 0.0322 42 

TRT03 

(Holtville, CA/ 

2005) 04-CA100 

Dimilin 

2L 

1. Broadcast/ Bloom 28 0.0323 - 

0.0962 

Amigo Vegetable 

Oil Surfactant 

(93% Vegetable Oil)

2. Broadcast/Bud, Bloom, Seed 

Pod 28 0.0314 14 

3. Broadcast/Bud, Bloom, SeedFruiting 28 0.0325 14 

(Holtville, CA/ 

2005) 05-CA01 

Dimilin 

2L 

1. Broadcast/Bloom 29 0.0335 - 

0.0989 

Amigo Vegetable 

Oil Surfactant 

(93% Vegetable Oil)

2. Broadcast/Bud, Bloom, Seed 

Pods 29 0.0326 15 

3. Broadcast/Fruiting (Seed) 28 0.0328 14 

(Fort Collins, 

CO/2005) 

05-CO01 

Dimilin 

2L 

1. Broadcast/Reproductive; past 

full bloom; pods present on plants 26 0.0337 - 

0.0972 Clean Crop Oil 

Concentrate 2. Broadcast/ Reproductive; past 

full bloom; pods on plants 25 0.0321 14 

3. Broadcast/Harvest maturity 24 0.0314 14 

(Touchet, WA/ 

2005) 05-WA01 

Dimilin 

2L 

1. Broadcast/Seeding 21 0.0320 - 

0.0975 

Lilly Miller 

Superior Type 

Spray Oil 

2. Broadcast/Seed 26 0.0324 14 

3. Broadcast/Seeded 27 0.0332 13 

(Kimberly, ID/ 

2005) 05-ID01 

Dimilin 

2L 

1. Broadcast/Early Bloom 25 0.0322 - 

2. Broadcast/ Early Bloom 25 0.0318 13 0.0953 Mor-Act 

3. Broadcast/Bloom 25 0.0322 13 1

EP = End-use Product 

2

Gallons per acre 

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 Crop 

Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 7 of 11

TABLE B.1.3 Trial Numbers and Geographical Locations 

NAFTA Growing Zones 

Alfalfa 

Submitted Requested 

1 1 

1A 

2 

3 1 

4 

5 6 

5A 

5B 

6 

7 1 

7A 

8 2 

9 1 

10 3 1 

11 4 1 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total1 9 12 

 1A total of nine field trials were conducted in EPA Regions 8, 10 and 11 because the request for this project was for a regional tolerance. Three 

field trials were conducted in 2004, while six field trials were conducted in 2005. 

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 Crop 

Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 8 of 11

B.2. Sample Handling and Preparation

Representative forage samples were harvested at the field sites at the late bud to early bloom 

stage (first cut), and/or at early (one-tenth) bloom stage (later cuts) [TRT 02], 1 day after each 

application. Duplicate forage samples were collected from each control and treated plot. A 

minimum of approximately 2 pounds of alfalfa forage was collected per sample. Hay samples 

were harvested 1 day PHI from at least 12 separate areas of each plot and allowed to dry in the 

field to a moisture content of approximately 10-20% (89-90% dry matter). When rainy weather 

was expected, the hay samples were removed to a sheltered area for drying. A total of three 

cuttings were made to each plot. A minimum of approximately 1 pound of alfalfa hay (4-22% 

moisture) was collected per sample. Alfalfa seed samples were collected at 1 day PHI. At some 

sites, alfalfa was cut, dried, and then combined for seed collection. A minimum of 

approximately 4 ounces of alfalfa seed was collected per sample. This low collection weight was 

due to poor seed set in the field due to moist weather, lack of pollinators and insect damage. 

Alfalfa forage, hay and seed samples were placed in labeled sample bags and held in frozen 

storage until shipment to the analytical laboratory. All treated samples (forage, hay and seed) 

were placed in frozen storage within 2 hours of sampling, and shipped frozen by ACDS freezer 

truck. All samples were received intact and in frozen condition at the analytical laboratory 

(PTRL West, Inc., Hercules, CA). After inspection of the samples at the time of receipt, they 

were assigned unique laboratory numbers and placed in freezer storage at <-5°C until sample 

preparation and analysis. Frozen alfalfa forage and hay samples were subsampled by processing 

the samples into a fine consistency using a Hobart Cutter-Mixer 61 in the presence of dry ice. 

Processed samples were transferred to open double zip-loc bags and stored in the freezer to allow 

the dry ice to sublime. Samples were sealed and maintained frozen until subsampling for 

analysis. Alfalfa seed samples were not mechanically processed prior to extraction. 

B.3. Analytical Methodology

Residues of diflubenzuron in/on alfalfa forage, hay and seed were quantified by LC/MS/MS 

using a method derived from “Diflubenzuron: Magnitude of the Residue in Small Grains” by 

Janine Rose, Ph.D., IR-4 Study 08024, PTRL Study 1129W, July 28, 2004. Method 

modifications did not negatively affect the performance of the method. 

Residues of diflubenzuron were extracted from alfalfa forage (10 grams), hay (10 grams) or 

seeds (5 grams) by repeatedly extracting with acetonitrile and the extracts combined. The 

volume was adjusted to measurable volume and a 50% aliquot was removed for further clean-up. 

The extract was repeatedly partitioned with hexane and the combined hexane partitions were 

discarded. The remaining acetonitrile extract was roto-evaporated to dryness and reconstituted 

with a 2 mL acetonitrile. The reconstituted acetonitrile extract was passed through a preconditioned C18-SPE cartridge for clean-up followed by additional clean-up using a Si-SPE 

cartridge. The solvent was evaporated and the residue was reconstituted in acetonitrile and 

water. Samples were analyzed by LC/MS/MS. The LOD for this method was 0.025 ppm and 

the LOQ, which was taken as the lowest level of method validation (LLMV), was 0.05 ppm in 

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Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 9 of 11

alfalfa forage and seed, and 0.5 ppm in alfalfa hay. 

The method was validated prior to sample analysis using control alfalfa hay and seed fortified 

with diflubenzuron at 0.05-5.0 ppm. Method validation in alfalfa hay was utilized as the relevant 

method validation for forage. 

C. RESULTS AND DISCUSSION 

The provided analytical method was adequate for data collection. Recovery data for control 

samples fortified with diflubenzuron and analyzed both prior to, and concurrently with, fieldtreated samples are summarized in Table C.1. Method validation recoveries of diflubenzuron on 

alfalfa hay and seed were within the acceptable range of 70% to 120%. No quantifiable residues 

of diflubenzuron were detected in untreated control alfalfa forage, seed, and hay samples from all 

field sites. 

Following three applications of diflubenzuron at 0.0325 lb ai/A, three forage and hay sample 

cuttings, and a PHI of 1 day, the maximum residues of diflubenzuron were 2.89 ppm in alfalfa 

forage and 9.072 ppm in alfalfa hay and the maximum residue of diflubenzuron in alfalfa seed 

was 0.434 ppm. Storage stability analysis was not conducted for this study, but was done in IR-4 

Study Number B8678 (MRID No. 49399502). Residues of the metabolites CPU and PCA were 

not quantified in this study. 

TABLE C.1. Summary of Concurrent and Method Recoveries of Diflubenzuron from Alfalfa.

Analyte Matrix Spike Level 

(ppm) Sample Size (n) Recoveries (%) Mean ± Std Dev (%) 

Concurrent 

Diflubenzuron 

Alfalfa 

Forage 

0.05 4 124, 78, 66, 72 85  26 

1 2 98, 101 100  2 

2 8 101, 103, 98, 87, 73, 82, 92, 96 92 ± 10 

Alfalfa 

Hay 

0.50 1 105 - 

5 1 95 - 

10 9 92, 88, 90, 65, 68, 83, 74, 88, 74 80 ± 10 

Alfalfa 

Seed 

0.05 3 80, 80, 78 79 ± 1 

0.5 4 96, 90, 99, 87 93 ± 5 

Method Validation 

Diflubenzuron 

Alfalfa 

Hay 

0.5 3 91, 97, 73 87 ± 12 

5.0 3 99, 101, 104 101 ± 3 

Alfalfa 

Seed 

0.05 3 86, 86, 86 86 ± 0 

0.5 3 91, 96, 91 93 ± 3 

TABLE C.2. Summary of Storage Conditions.

Matrix (RAC) Storage Temperature 

(°C) 

Actual Storage Duration 

(days) 

Interval of Demonstrated 

Storage Stability1

Alfalfa forage 

<-5°C 

34-244 

Alfalfa hay 38-216 

Alfalfa seed 15-196 1

Storage stability analysis was not conducted for this study, but was done in IR-4 Study Number B8678 (MRID No. 49399502). 

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Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 10 of 11

TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron. 

Trial ID 

(City, State/Year) Zone Crop/Variety Commodity or Matrix 

Total 

Rate 

(lb ai/A) 

PHI 

(days) 

Diflubenzuron (ppm)1

1st cutting 2nd cutting 3rd cutting 

04-CO09 (Fort Collins, CO 

/2004)2 8 Alfalfa/ 

Focus Forage 0.0972 1 1.24, 1.97 1.580, 

1.924 2.25, 1.67 

04-ID04 (Kimberly, ID 

/2004) 11 Alfalfa/ Rampage Forage 0.1040 1 2.19, 2.89 

04-WA09 (Prosser, WA 

/2004) 11 Alfalfa/ Perfect A1 Forage 0.0956 1 1.67, 1.48 

05-CO01 (Fort Collins, CO 

/2005) 8 Alfalfa/ Focus Forage 0.1000 1 1.85, 1.43 2.31, 2.05 

04-CA100 (Holtville, CA/ 

2005) 10 Alfalfa/ Cibola Forage 0.0962 1 1.86, 1.93 

05-CA01 (Holtville, CA/ 

2005) 10 Alfalfa/ 

Cibola Forage 0.0989 1 1.10, 1.20 

05-CA02 (Davis, CA/ 

2005) 10 Various 

varieties Forage 0.0996 1 2.22, 2.42 

05-ID01 (Kimberly, ID/ 

2005) 11 DK 140 Forage 0.0953 1 1.50, 1.59 

05-WA01 (Prosser, WA/ 

2005) 11 Alfalfa/ 

Perfect A1 Forage 0.0975 1 0.820, 0.960

04-CO09 (Fort Collins, CO 

/2004) 8 Alfalfa/ 

Focus Hay 0.0972 1 - - 6.61, 6.16 

04-ID04 (Kimberly, ID 

/2004) 11 Alfalfa/ Rampage Hay 0.1043 1 - - 5.82, 9.07 

04-WA09 (Prosser, WA 

/2004) 11 Alfalfa/ Perfect A1 Hay 0.0956 1 - - 5.49, 4.93 

04-CA100 (Holtville, CA/ 

2005) 10 Alfalfa/ Cibola Hay 0.0962 1 - - 4.17, 4.65 

05-CA01 (Holtville, CA/ 

2005) 10 Alfalfa/ 

Cibola Hay 0.0989 1 - - 3.34, 3.58 

05-CO01 (Fort Collins, CO 

/2005) 8 Alfalfa/ 

Focus Hay 0.0972 1 - - 8.28, 8.04 

05-CA02 (Davis, CA/ 

2005) 10 

Various 

varieties per 

plot 

Hay 0.0996 1 - - 5.40, 5.04 

05-ID01 (Kimberly, ID/ 

2005) 11 Alfalfa/DK 140 Hay 0.0953 1 - - 4.34, 4.54 

05-WA01 (Prosser, WA/ 

2005) 11 Alfalfa/ Perfect A1 Hay 0.0975 1 - - 2.61, 3.18 

05-CA01 (Holtville, CA/ 

2005) 

10 Alfalfa/ 

Cibola Seed 0.0989 1 - - 0.19, 0.070

04-CA100 (Holtville, CA/ 

2005) 

10 Alfalfa/ 

Cibola Seed 0.0962 1 - - 0.270, 0.420

05-CO01 (Fort Collins, CO 

/2005) 

8 Alfalfa/ 

Focus Seed 0.0972 1 - - 0.430, 0.430

05-ID01 (Kimberly, ID/ 

2005) 

11 Alfalfa/DK 

140 Seed 0.0953 1 - - 0.160, 0.160

05-WA01 (Prosser, WA/ 

2005) 

11 Alfalfa/ 

Perfect A1 Seed 0.0975 1 - - 0.056, 0.079

1

Samples were not analyzed for the metabolites CPU, and PCA. 

2

Residues were found to increase from the first to the third cutting at trial site CO09. Therefore, the forage and hay samples from the third cutting 

were the only samples analyzed in the remaining trials (except for the first forage cutting in the 05-CO01 trial). 

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 Crop 

Field Trial/ Residue Decline - Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399501 Page 11 of 11

TABLE C.4. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total 

Applic. Rate 

(lb ai/A) 

PHI 

(days) 

Diflubenzuron 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Alfalfa Forage2

0.10 1 

18 0.82 2.9 2.5 1.8 1.8 0.50 

Alfalfa Hay2 18 2.6 9.1 8.2 5.2 5.3 1.8 

Alfalfa Seed 10 0.056 0.43 0.43 0.18 0.23 0.15 1

HAFT = Highest Average Field Trial 

2

Alfalfa forage and hay 3rd cutting 

D. CONCLUSION 

The residue studies were conducted consistent with standard agricultural practices as per 

proposed experimental designs. No anomalous weather events were recorded, except for cooler 

temperature and a few rain events in early March at the CA100 field trial and heavy rain and 

small hail at the CO09 field trial site. These events had no adverse impact on the crops. 

The LC/MS/MS residue analytical method used for determining diflubenzuron in/on alfalfa 

forage, hay and seed was validated and adequate for data collection. Storage stability analysis on 

frozen stored samples was not conducted for this study, but was done in IR-4 Study Number 

B8678 (MRID No. 49399502). 

Following three foliar applications of Dimilin 2L, with the use of an emulsified vegetable or 

paraffinic crop oil, at a maximum seasonal rate of 0.10 lb ai/A, and a 1-day PHI, the maximum 

residues of diflubenzuron were: 2.9, 9.1, and 0.43 ppm on alfalfa forage (3rd cutting), hay (3rd

cutting), and seed, respectively. A decline trial was not conducted and residues of the 

metabolites CPU and PCA were not quantified in this study. 

E. REFERENCES

US EPA DER (14-Sep-2006): MRID 46609501. Corley, J. (2005) Diflubenzuron: Magnitude of 

the Residue on Small Grain. Lab Project Number: 08024.02-PTR01. Unpublished study 

prepared by Interregional Research Project No. 4 (IR-4). 800 p. 

F. DOCUMENT TRACKING

RDI: T. Morton (6/20/2015) 

Petition Number(s): 4E8306 

DP Barcode(s): D423328 

PC Code: 108201 

Template Version June 2005.

Page 64 of 100
Di nubcnzuron/ I 0820 I /Chemtura Corvorat ion/400 

D/\CO 7.4.117.4.2/0PPTS 860.1500/0ECD II/\ 6.3.1. 6.3.2. 6.3.3 and Ill/\ 8.3.1, 8.3.2. 8.3.3 

Crop Field Trial - Alfalfa 

Primary Evaluator 

Peer Reviewer 

Approved by 

STUDY REPORTS: 

J Jesus Leyva 

Environmental Scientist, 

California Department 

"-V -"<J~ 

Theresa Rano, Ph.D., 

Senior Enviro"nmcntal Scientist (Specialist), 

Cal ifornia Department of Pesticide Regulation 

Thurston G. Morton, Chemist 

Date: 3/10/2015 

Date: 

ate: 6/15/2015 

HED/RABIV (7509P) JJ. 

Sumitra Bose Biswas, Chemist ~~ r/J. vv~ HED!RABVJ (7509P) 

MRID 10. 49399502 William P. Barney (20 14) Diflubenzuron: Magnitude of the Residue on 

Alfalfa. Lab Project Number: 88678. Unpublished study prepared by The Interregional 

RescaJch Project No. 4 (IR-4). 307 pages. 

EXECUTIVE SUMMARY: 

The IR-4 has submitted field trial data for diflubcnzuron on alfalfa. Three trials were conducted 

in the United States or Canada encompassing Zones I 0 (CA; I trial) and 11 (ID and WA; 2 

trials) during the 2011 growing season. At each test location, diOubenzuron (Dimilin 2L) was 

applied 3-4 times to alfalfa fields as a broadcast fol iar application to four treated plots. At the 

first treated plot at all sites. application rate was 0.0314-0.035 I lb ai/Napplication [Treatment 

(TRT) 02). At the second treated plot at all sites. application rate was 0.0934 to 0.0982 lb ai/A/ 

application (TRT 03). Three applications were made to the other two treated plots 12-15 days 

apart. The application rates were 0.0317-0.0339 lb ail A/application (TRT04) and 0.0940-0.1007 

lb ail A/application (TRTOS). J\n acljuvant was added to the spray mixture for all applications, 

except at the ID I 7 field trial for TRT 02 and TRT 03. 

At all the field trials, forage and hay samples were harvested I day aner each application to the 

TRT02 and TRT03 plots. Seed samples were harvested I day after the last application to the 

TRT04 and TRT05 plots. 

The harvested al fa! fa forage, hay and seed samples were analyzed for residues of di flubenzuron, 

4-chlorophenylurea (CPU). and 4-chloroaniline (PCA) .by liquid chromatography/tandem mass 

spectroscopy (LC/MS/MS) using modified methods derived from: "Dimilin 25W, Dimilin 

80WG and Dimi lin 2L in Almonds, Magnitude or the Residue Study," Author: Janine E. Rose, 

Dated September 13. I 999. Uniroyal Study No. RP-98003. The methods were adequately 

PMR/\ Submission No. /DP Barcodc 0423328 /MRID No.49399502 Page I or 14 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 2 of 14

validated in conjunction with the field sample analyses. The lowest level of method validation 

(LLMV) for residues of diflubenzuron in/on alfalfa samples was 0.050 ppm and the LLMV for 

residues of CPU and PCA in/on alfalfa samples was 0.005 ppm. 

Residues of diflubenzuron from the TRT02 plot ranged from <0.05-5.73 ppm and 2.9-15.6 ppm 

in forage and hay samples, respectively. Residues of diflubenzuron from the TRT03 plot ranged 

from <0.05-11.6 ppm and 7.5-45 ppm in forage and hay samples, respectively. Residues of 

diflubenzuron in seed samples ranged from <0.05-60.3 ppm and 0.36-2.04 ppm in TRT04 and 

TRT05 plots, respectively. 

Residues of CPU and PCA were <0.005 ppm for all forage seed samples. Residues of CPU in 

hay ranged from <0.005-0.105 ppm (TRT02) and <0.005-0.144 ppm (TRT03). Residues of PCA 

in hay were <0.005 ppm (TRT02) and <0.005-0.00664 ppm (TRT03). 

The maximum storage intervals for field-treated samples in this study were 322 days, 294, and 

259 days for forage, hay and seed, respectively. 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS: 

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document [DP Barcode Dxxxxxx]. 

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. This study meets current GLP Requirements of 40 CFR Part 160, 

with the following deviations, which do not affect the conclusions presented in this report: 

1. Supporting data such as weather/irrigation, soil characterization records; test site history 

and cultural practices; and maintenance fertilizers and pesticides data were not collected 

in strict adherence to 40 CFR 160 guidelines. 

2. At all trials the scale used for obtaining field sample weights was not maintained 

according to GLP standards. 

3. At the ID17 and WA*33 trials the pH meter/paper used to measure acidity of carrier 

water was not maintained according to GLP standards. 

A. BACKGROUND INFORMATION

Diflubenzuron is an insecticide/acaricide (insect growth regulator) that behaves as a chitin 

inhibitor to suppress the growth of many leaf-eating larvae, mosquito larvae, aquatic midges, rust 

mite, boll weevil, and flies. Diflubenzuron was first registered in the United States in 1979 for 

use as an insecticide. The Agency issued a Registration Standard for diflubenzuron in 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 3 of 14

September, 1985, (NTIS #PB86-176500). Diflubenzuron was also the subject of a Residue 

Chemistry Chapter dated 11/16/84, an Addendum to the Registration Standard dated 12/4/84, 

and a Reregistration Standard Update dated 6/21/91. The Reregistration Eligibility Decision 

(RED) for diflubenzuron was issued in August, 1997 (EPA 738-R-97-008). Tolerances for 

residues of diflubenzuron are established under 40 CFR §180.377 [US EPA Data Evaluation 

Record (DER) 11/14/2006]. 

 

TABLE A.1. Test Compound Nomenclature.

Diflubenzuron 

H

N

O

H

N

O

F

F

Cl

Common name Diflubenzuron 

Company experimental name DU 112307 

IUPAC name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS # 35367-38-5 

End-use product/(EP) 2 lb/gal FIC formulation, Dimilin® 2L (EPA Reg. No. 400-461) 

Regulated Metabolite 

O

N

H

Cl

2NH

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite 

Cl

2NH

Common Name 4-chloroaniline (PCA) 

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

Melting point/range 210-230°C 

(US EPA DER, 11/14/2006) 

pH Not available 

Density (22°C) Not available 

Water solubility (25°C) 0.08 ppm 

Solvent solubility (g/L at 25°C) 

6.5 x 103

 Acetone 

2 x 103

 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105

 Dimethylsulfoxide 

1 x 103

 Methanol 

6 x 102

 Dichloromethane 

Vapour pressure at 25°C 1.2x10-4mPA (9.0x10-10 mmHg) 

Dissociation constant (pKa) Does not dissociate 

Octanol/water partition coefficient Log(KOW) 3.89 

UV/visible absorption spectrum Not available 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 4 of 14

B. EXPERIMENTAL DESIGN

B.1. Study Site Information 

TABLE B.1.1 Trial Site Conditions.

Trial Identification (City, State/Year) 

Soil characteristics1

Type %OM pH CEC 

meq/g 

CA147 (Holtville, CA/2011) Silty Clay Loam 0.5 8.2 26 

ID17 (Kimberly, ID/2011) TRT02 and TRT03 Silt Loam 1.88 8.2 16.9 

ID17 (Jerome, ID/2011) TRT04 and TRT05 Loam 2.13 7.7 16.4 

WA*33 (Moxee, WA/2011) Sandy Loam 1.22 7.8 22.5 1

These parameters are optional except in cases where their value affects the use pattern for the chemical. 

The actual temperature recordings were within average historical values for the residue study 

period, except temperatures during the WA*33 field trial were lower than normal. The actual 

rainfall average was within the historical rainfall average, except rainfall during the WA*33 field 

trial was higher than normal. Irrigation was used to supplement as needed. 

TABLE B.1.2 Study Use Pattern.

Location 

(City, 

State/Year) 

Trial ID 

EP1

Application 

Tank Mix/ 

Method/Timing Adjuvants Volume 

GPA2

Rate 

(lb ai/A) 

RTI3

(days) 

Total Rate 

(lb ai/A) 

TRT02 

(Holtville, CA/ 

2011) CA147 

Dimilin 

2L 

1. Foliar Broadcast/40% open 

bloom 

22 0.0314 - 

0.1290 Methylated 

Oil 

2. Foliar Broadcast/5% open 

bloom 

23 0.0321 33 

3. Foliar Broadcast/5% open 

bloom 

23 0.0330 28 

4. Foliar Broadcast/1% open 

bloom4

24 0.0325 28 

(Kimberly, ID/ 

2011) ID17 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 25 0.0334 - 

0.1016 

None 

2. Foliar Broadcast/Flowering 26 0.0351 47 Mor-Act 

3. Foliar Broadcast/Mature 25 0.0331 45 (COC) 

(Moxee, WA/ 

2011) WA*33 

Dimilin 

2L 

1. Foliar Broadcast/Bloom 24 0.0327 - 

0.0978 SunSpray 

oil 

2. Foliar Broadcast/Bloom 22 0.0320 42 

3. Foliar Broadcast/Bloom 23 0.0330 35 

TRT03 

(Holtville, CA/ 

2011) CA147 

Dimilin 

2L 

1. Foliar Broadcast/40% bloom 22 0.0934 - 

0.3808 Methylated 

Oil 

2. Foliar Broadcast/5% bloom 23 0.0959 33 

3. Foliar Broadcast/5% bloom 23 0.0978 28 

4. Foliar Broadcast/1% bloom 23 0.0937 78 

(Kimberly, ID/ 

2011) ID17 Dimilin 

2L 

1. Foliar Broadcast/Vegetative 25 0.0982 - 

0.2907 

None 

2. Foliar Broadcast/Flowering 25 0.0976 47 Mor-Act 

3. Foliar Broadcast/Mature 24 0.0949 45 (COC) 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 5 of 14

TABLE B.1.2 Study Use Pattern.

Location 

(City, 

State/Year) 

Trial ID 

EP1

Application 

Tank Mix/ 

Method/Timing Adjuvants Volume 

GPA2

Rate 

(lb ai/A) 

RTI3

(days) 

Total Rate 

(lb ai/A) 

(Moxee, WA/ 

2011) WA*33 Dimilin 

2L 

1. Foliar Broadcast/Bloom 24 0.0980 - 

0.2896 SunSpray 

oil 2. Foliar Broadcast/Bloom 22 0.0949 42 

3. Foliar Broadcast/Bloom 22 0.0967 35 

TRT04 

(Holtville, CA/ 

2011) CA147 Dimilin 

2L 

1. Foliar Broadcast/Bloom & pod 22 0.0314 - 

0.0967 Methylated 

Oil 2. Foliar Broadcast/ Bloom & pod 23 0.0321 14 

3. Foliar Broadcast/Seed head 23 0.0330 15 

(Jerome, ID/ 

2011) ID17 Dimilin 

2L 

1. Foliar Broadcast/Seed pod fill 25 0.0334 - 

0.1011 Mor-Act 

(COC) 2. Foliar Broadcast/Seed pod fill 26 0.0351 13 

3. Foliar Broadcast/Mature 25 0.0331 12 

(Moxee, WA/ 

2011) WA*33 Dimilin 

2L 

1. Foliar Broadcast/Bloom 24 0.0327 - 

0.0969 SunSpray 

oil 2. Foliar Broadcast/Bloom/Seed 22 0.0320 15 

3. Foliar Broadcast/Seed 23 0.0330 14 

TRT05 

(Holtville, CA/ 

2011) CA147 Dimilin 

2L 

1. Foliar Broadcast/Bloom & pod 23 0.0954 - 

0.2919 Methylated 

Oil 2. Foliar Broadcast/ Bloom & pod 23 0.0963 14 

3. Foliar Broadcast/ Seed head 24 0.1002 15 

(Jerome, ID/ 

2011) ID17 Dimilin 

2L 

1. Foliar Broadcast/ Seed pod fill 25 0.0978 - 

0.2978 Mor-Act 

(COC) 2. Foliar Broadcast/ Seed pod fill 26 0.1007 13 

3. Foliar Broadcast/Mature 25 0.0994 12 

(Moxee, WA/ 

2011) WA*33 Dimilin 

2L 

1. Foliar Broadcast/Bloom 22 0.0940 - 

0.2891 SunSpray 

oil 2. Foliar Broadcast/Bloom/Seed 23 0.0996 15 

3. Foliar Broadcast/Seed 22 0.0955 14 1

EP = End-use Product 

2

Gallons per acre 

3

Retreatment Interval 

4

Hay samples taken after the third application were lost in a dust storm. The fourth application was made to collect a third sample of hay 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 6 of 14

TABLE B.1.3 Trial Numbers and Geographical Locations 

NAFTA Growing Zones 

Alfalfa 

Submitted Requested 

1 

1A 

2 

3 

4 

5 

5A 

5B 

6 

7 

7A 

8 

9 

10 1 

11 2 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total 3 3 1Per a US EPA ChemSAC decision, these trials are required to supplement data from PR 08678 (MRID No. 49399501) 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 7 of 14

B.2. Sample Handling and Preparation

Duplicate representative alfalfa forage and hay samples were harvested at all field trials 1 day 

after each application from TRT02 and TRT03 and control plots. Seed samples were harvested 1 

day after the last application to TRT04 and TRT05 plots. The samples were shipped frozen to 

the USDA-ARS (Beltsville) analytical laboratory by ACDS freezer truck.. All samples arrived 

frozen and intact at the analytical laboratory. The samples were checked in, ground with dry ice 

and stored frozen until extraction and analysis. Samples were analyzed for the parent compound, 

diflubenzuron, at the ARS facility. Prior to the analysis for the metabolites, the Beltsville facility 

was closed by USDA-ARS, and no further work was done on this study. The residue and 

fortified samples were transferred via ACDS freezer truck to the USDA-ARS laboratory in 

Tifton, Georgia, for storage and subsequently shipped to Smithers Viscient in Wareham, 

Massachusetts for complete residue analyses. All samples arrived frozen and intact and were 

stored frozen (generally <-20 oC). The field samples were analyzed for diflubenzuron, CPU and 

PCA. Storage stability samples were analyzed to ensure stability of analytes during shipping. 

B.3. Analytical Methodology

Residues of diflubenzuron, CPU, and PCA in/on alfalfa forage, hay and seed were quantified by 

LC/MS/MS using methods derived from the reference methods: “Diflubenzuron: Magnitude of 

the Residue in Small Grains”. Janine E. Rose, Ph.D., IR-4 Study 08024, PTRL Study 1129W, 

July 28, 2004, and “Dimilin 25W, Dimilin 80WG and Dimilin 2L in Almonds, Magnitude of the 

Residue Study”, Author: Janine E. Rose, Uniroyal Study No. RP-98003, September 13, 1999. 

For analysis of diflubenzuron and CPU, 5 g of processed sample matrix was homogenized, 

centrifuged, and extracted three times with acetonitrile. The acetonitrile layers were collected 

and taken to a final volume of 80.0 mL with acetonitrile. The sample was further diluted into the 

calibration standard range with purified regent water and/or 10:90 acetonitrile:purified reagent 

water (v:v). If particles were, the sample was centrifuged at 13,000 rpm for five minutes prior to 

analysis by LC/MS/MS. The calculated LODs for diflubenzuron residues on alfalfa forage, hay 

and seed samples were 0.01428, 0.01726 and 0.01624 ppm, respectively. The calculated LOQs 

for diflubenzuron residues on alfalfa forage, hay and seed were 0.04283, 0.05177 and 0.04871 

ppm, respectively. The calculated LODs for CPU residues on alfalfa forage, hay and seed 

samples were 0.00156, 0.00123 and 0.00152 ppm, respectively. The calculated LOQs for CPU 

residues on alfalfa forage, hay and seed were 0.00469, 0.00370 and 0.00456 ppm, respectively. 

The lowest level of method validation (LLMV) was 0.05 ppm for diflubenzuron and 0.005 ppm 

for CPU on alfalfa forage, hay and seed. 

For PCA detection, 5 g of processed sample matrix was fortified with the internal standard 

(

13C6)4-chloroaniline). The fortified sample was vortexed then allowed to settle with the cap off 

for five minutes. The sample was then extracted with 0.1 N hydrochloric acid solution (in 

purified regent water) and shaken at 60 oC for 30 minutes, brought to room temperature in a cold 

water bath, then centrifuged. The supernatant was then filtered and the remaining pellet was 

extracted twice more. Both extractions were collected and taken to a final volume of 100 mL 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 8 of 14

with 0.1N hydrochloric acid solution. The sample was further diluted into the calibration 

standard range with 10 mM ammonia formate solution (in purified reagent water). If particles 

were present, the sample was centrifuged at 13,000 rpm for five minutes prior to analysis by 

LC/MS/MS. 

The calculated LODs for PCA residues on alfalfa forage, hay and seed samples were 0.00128, 

0.00096 and 0.00098 ppm, respectively. The calculated LOQs for PCA residues on alfalfa 

forage, hay and seed were 0.00385, 0.00289 and 0.00294 ppm, respectively. The LLMV was 

0.005 ppm for PCA on alfalfa forage, hay and seed. 

The methods were validated both prior to and concurrently with field trial samples of alfalfa 

forage, hay and seed matrices fortified with diflubenzuron, CPU and PCA at 0.005-50 ppm. 

C. RESULTS AND DISCUSSION 

The provided analytical methods were adequate for data collection. Recovery data for control 

samples fortified with diflubenzuron, CPU, and PCA and analyzed both prior to, and 

concurrently with, field-treated samples are summarized in Table C.1. Fortification levels 

ranged from 0.005 to 0.5 ppm. Method validation recoveries were within the acceptable range of 

70% to 120% for diflubenzuron, CPU, and PCA on alfalfa forage, alfalfa hay and alfalfa seed. 

The maximum storage interval for field-treated samples in this study was 322 days for forage, 

294 days for hay and 259 days for seed (Table C.2). Storage stability samples were fortified 

with diflubenzuron, CPU and PCA at 0.5 ppm and 0.05 ppm respectively; and held in frozen 

storage under similar conditions to the field generated samples. 

Diflubenzuron residues (TRT02) ranged from <0.05-5.73 ppm and 2.9-15.6 ppm in forage and 

hay samples, respectively. From the TRT03 plot, diflubenzuron residues ranged from <0.05-

11.6 ppm and 7.5-45 ppm in forage and hay samples, respectively. Residues of diflubenzuron in 

seed samples ranged from <0.050-60.3 and 0.360 to 2.04 ppm in the TRT04 and TRT05 plots, 

respectively. Residues of CPU were <0.005 ppm in all alfalfa hay and seed samples. Residues 

in alfalfa forage ranged from <0.005-0.105 ppm and <0.005-0.144 ppm in TRT02 and TRT03 

plots, respectively. Residues of PCA were <0.005 ppm in all alfalfa forage and seed samples. 

Residues in alfalfa hay were <0.005 ppm for the TRT02 samples and ranged from <0.005-

0.00664 ppm for TRT03 samples (Table C.3). 

TABLE C.1. Summary of Concurrent and Method Recoveries of Diflubenzuron, CPU and PCA from 

Alfalfa

Analyte Matrix Spike Level 

(ppm) Sample Size (n) Recoveries (%) Mean ± Std Dev 

(%) 

Concurrent 

Diflubenzuron Alfalfa 

Forage 

0.05 9 79, 77, 72, 72, 84, 79, 82, 79, 87 79  5 

0.5 3 74, 74, 86 78  7 

10 6 90, 91, 94, 102, 104, 115 99  10 

15 3 101, 98, 90 96 ± 6 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 9 of 14

TABLE C.1. Summary of Concurrent and Method Recoveries of Diflubenzuron, CPU and PCA from 

Alfalfa

Analyte Matrix Spike Level 

(ppm) Sample Size (n) Recoveries (%) Mean ± Std Dev (%) 

CPU 

0.005 10 93, 79, 73, 73, 72, 71, 78, 73, 76, 

76 76 ± 6 

0.05-0.5 8 74, 74, 84, 112, 103, 88, 90, 94 90 ± 13 

PCA 

0.005 10 106, 105, 116, 112, 100, 79, 105, 

105, 109, 118 106 ± 11 

0.05-0.5 5 103, 85, 110, 112, 84 99 ± 13 

Diflubenzuron 

Alfalfa 

Hay 

0.05-0.5 11 73, 81, 79, 103, 67, 73, 78, 84, 

75, 77, 101 81 ± 11 

10-20 6 86, 101, 86, 97, 100, 100 95 ± 7 

25-50 4 90, 85, 87, 120 96 ± 16 

CPU 

0.005-0.05 11 91, 104, 88, 79, 90, 94, 110, 84, 

86, 75, 76 89 ± 11 

0.5 5 103, 112, 86, 97, 81 96 ± 13 

PCA 

0.005 7 115, 105, 116, 103, 104, 113, 

108 109  5 

0.05-0.5 8 118, 108, 92, 93, 84, 88, 109, 

120 102  14 

Diflubenzuron 

Alfalfa 

Seed 

0.05 6 120, 113, 103, 81, 104, 115 106  14 

0.5 2 98, 120 109  16 

10 3 95, 97, 109 100  9 

CPU 

0.005 8 101, 96, 110, 80, 75, 77, 98, 98 92  13 

0.05-0.5 4 90, 99, 100, 113 100  9 

PCA 

0.005 8 94, 94, 98, 101, 98, 102, 100, 

120 101  8 

0.05-0.5 4 84, 116, 91, 113 101  16 

Method Validation 

Diflubenzuron 

Alfalfa 

Forage 

0.05 3 95, 90, 98 94  4 

1.0 3 95, 94, 97 95  2 

10 3 95, 97, 103 98  4 

CPU 

0.005-0.05 6 90, 88, 96, 99, 108, 117 100  11 

0.5 3 92, 93, 103 96  6 

PCA 

0.005 3 116, 116, 119 117  2 

0.05 3 109, 112, 106 109  3 

0.5 3 107, 104, 95 102  6 

Diflubenzuron 

Alfalfa 

Hay 

0.05 3 84, 91, 86 87  3 

1.0 3 83, 86, 82 88  1 

10 3 91, 95, 88 91  4 

CPU 

0.005 3 93, 96, 91 93  3 

0.05 3 85, 93, 94 91  3 

0.5 3 82, 86, 90 86  4 

PCA 

0.005 3 113, 110, 104 109  5 

0.05 3 115, 115, 108 112  4 

0.5 3 109, 114, 106 110  4 

Diflubenzuron Alfalfa 0.05 3 87, 84, 89 87  3 

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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 10 of 14

TABLE C.1. Summary of Concurrent and Method Recoveries of Diflubenzuron, CPU and PCA from 

Alfalfa

Analyte Matrix Spike Level 

(ppm) Sample Size (n) Recoveries (%) Mean ± Std Dev (%) 

Seed 1.0 2 88, 87 88  1 

10 3 86, 91, 95 91  4 

PCU 

0.005 3 113, 110, 104 109  5 

0.05 3 115, 115, 108 112  4 

0.5 3 109, 114, 106 110  4 

PCA 

0.005 3 98, 92, 96 95  3 

0.05 3 99, 100, 98 99  1 

0.5 3 92, 93, 95 93  2 

TABLE C.2. Summary of Storage Conditions.

Matrix 

(RAC) 

Storage 

Temperature 

(°C) 

Actual Storage Duration 

(days) 

Interval of Demonstrated Storage 

Stability 

(days) 

Diflubenzuron 

Alfalfa Forage 

<-20 

322 306 

Alfalafa Hay 294 306 

Alfalfa Seed 259 307 

CPU

Alfalfa Forage 

<-20 

322 300 

Alfalafa Hay 294 301 

Alfalfa Seed 259 302 

PCA 

Alfalfa Forage 

<-20 

322 300 

Alfalafa Hay 292 301 

Alfalfa Seed 256 303 

Page 74 of 100
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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 11 of 14

TABLE C.2.2 Stability of Diflubenzuron and its Metabolites in Frozen Alfalfa Forage, Hay and Seed 

Matrix Analyte Spike Level 

(ppm) 

Interval of 

demonstrated 

storage 

stability 

(Days) 

Freshly Fortified 

Recoveries (%) 

[Average] 

Stored Sample 

Recoveries (%) 

[Average]

Average 

Corrected Stored 

Recovery (%)

Alfalfa 

Forage 

Diflubenzuron 0.5 306 74, 74, 86 [78] 72, 74, 70 [72] 92 

CPU 0.05 300 74, 74 [74] 67, 85, 68 [73] 99 

PCA 0.05 300 110 23. 21, 20 [21] 19 

Alfalfa 

Hay 

Diflubenzuron 0.5 306 75, 101 [88] 60. 53, 55 [56] 64 

CPU 0.005-0.5 43 118, 118, 110, 84 

[108] 56, 56, 54 [55] 51 

PCA 0.05 301 120, 88 [104] 42. 32, 45 [40] 38 

Alfalfa 

Seed 

Diflubenzuron 0.5 307 120 72. 67, 73 [71] 59 

CPU 0.005-0.5 43 98, 100, 113, 99 

[102] 63, 71, 72 [67] 66 

PCA 0.005-0.5 42 120, 116, 113, 84 

[108] 38, 40, 42 [40] 37 

TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/ 

Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

TRT

# 

Total 

Rate 

(lb ai/A)

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

CPA 

(ppm) 

Combined 

Residues 

(ppm)1

CA147 

(Holtville, CA/ 

2011) 

10 Alfalfa/ 

CUF 101 Forage 

02 0.1290 1 

2.57 <0.005 <0.005 2.582

2.37 <0.005 <0.005 2.382

1.99 <0.005 <0.005 2.003

2.44 <0.005 <0.005 2.453

5.73 <0.005 <0.005 5.744

1.44 <0.005 <0.005 1.454

03 0.3808 1 

4.24 <0.005 <0.005 4.252

5.15 <0.005 <0.005 5.162

4.05 <0.005 <0.005 4.063

3.75 <0.005 <0.005 3.763

11.6 <0.005 <0.005 11.614

7.77 <0.005 <0.005 7.784

ID17 

(Kimberly, ID/ 

2011) 

11 Alfalfa/ 

Sundance Forage 

02 0.1016 1 

0.76 <0.005 <0.005 0.772

0.74 <0.005 <0.005 0.752

1.15 <0.005 <0.005 1.163

1.61 <0.005 <0.005 1.623

<0.05 <0.005 <0.005 0.064

1.67 <0.005 <0.005 1.684

03 0.2907 1 

1.53 <0.005 <0.005 1.542

1.95 <0.005 <0.005 1.962

2.66 <0.005 <0.005 2.673

2.31 <0.005 <0.005 2.323

3.39 <0.005 <0.005 3.404

3.57 <0.005 <0.005 3.584

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Forage 02 0.0978 1 

<0.05 <0.005 <0.005 0.062

<0.05 <0.005 <0.005 0.062

0.67 <0.005 <0.005 0.683

Page 75 of 100
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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 12 of 14

TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/ 

Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

TRT

# 

Total 

Rate 

(lb ai/A)

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

CPA 

(ppm) 

Combined 

Residues 

(ppm)1

1.09 <0.005 <0.005 1.103

1.22 <0.005 <0.005 1.234

1.77 <0.005 <0.005 1.784

03 0.2896 1 

<0.05 <0.005 <0.005 0.062

<0.05 <0.005 <0.005 0.062

3.18 <0.005 <0.005 3.193

4.40 <0.005 <0.005 4.413

4.92 <0.005 <0.005 4.934

6.05 <0.005 <0.005 6.064

CA147 

(Holtville, CA/ 

2011) 

10 Alfalfa/ 

CUF 101 Hay 

02 0.1290 1 

5.41 <0.005 <0.005 5.422

6.66 <0.005 <0.005 6.672

5.95 <0.005 <0.005 5.963

7.32 <0.005 <0.005 7.333

15.6 0.105 <0.005 15.714

10.8 0.0595 <0.005 10.864

03 0.3808 1 

13.5 <0.005 <0.005 13.512

13.0 <0.005 <0.005 13.012

9.49 <0.005 <0.005 9.503

11.5 <0.005 <0.005 11.513

45.0 0.144 <0.005 45.154

36.9 0.124 0.0056 37.034

ID17 

(Kimberly, ID/ 

2011) 

11 Alfalfa/ 

Sundance Hay 

02 0.1016 1 

5.15 <0.005 <0.005 5.162

4.03 <0.005 <0.005 4.042

5.58 <0.005 <0.005 5.593

5.92 <0.005 <0.005 5.933

4.71 <0.005 <0.005 4.724

4.60 <0.005 <0.005 4.614

03 0.2907 1 

15.5 <0.005 0.0066 15.512

10.9 <0.005 0.0054 10.912

12.0 <0.005 <0.005 12.013

12.3 <0.005 0.0053 12.313

10.1 <0.005 <0.005 10.114

12.3 <0.005 <0.005 12.314

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Hay 

02 0.0978 1 

2.90 <0.005 <0.005 2.912

4.12 <0.005 <0.005 4.132

3.83 <0.005 <0.005 3.843

3.79 0.0053 <0.005 3.803

4.35 <0.005 <0.005 4.364

5.13 <0.005 <0.005 5.144

03 0.2896 

1 11.00 <0.005 <0.005 11.012

7.50 <0.005 <0.005 7.512

19.10 0.0059 0.0052 19.113

13.90 0.0056 0.0057 13.913

18.60 0.0068 <0.005 18.614

15.60 <0.005 <0.005 15.614

CA147 

(Holtville, CA/ 

2011) 

10 Alfalfa/ 

CUF 101 Seed 

04 0.0967 1 0.23 <0.005 <0.005 0.24 

0.26 <0.005 <0.005 0.27 

05 0.2919 1 0.44 <0.005 <0.005 0.45 

0.36 <0.005 <0.005 0.37 

ID17 11 Alfalfa/ Seed 04 0.1010 1 <0.05 <0.005 <0.005 0.06 

Page 76 of 100
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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 13 of 14

TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/ 

Year) 

Zone Crop/ 

Variety 

Commodity 

or Matrix 

TRT

# 

Total 

Rate 

(lb ai/A)

PHI 

(days)

Diflubenzuron 

(ppm) 

CPU 

(ppm) 

CPA 

(ppm) 

Combined 

Residues 

(ppm)1

(Kimberly, ID/ 

2011) 

Sundance <0.05 <0.005 <0.005 0.06 

05 0.2978 1 0.079 <0.005 <0.005 0.09 

0.108 <0.005 <0.005 0.12 

WA*33 

(Moxee, WA/ 

2011) 

11 Alfalfa/ 

Ranger Seed 

04 0.0969 1 60.3 <0.005 <0.005 60.31 

34.5 <0.005 <0.005 34.51 

05 0.2891 1 1.10 <0.005 <0.005 1.11 

2.04 <0.005 <0.005 2.05 1

For residues <0.05 and <0.005 ppm, values of 0.05 and 0.005 ppm, respectively, were used to calculate the sum of combined residues 2

First cutting. 3Second cutting. 4Third cutting 

TABLE C.4. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity Total Applic. Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues of Diflubenzuron, CPU and PCA 

(ppm)1

n Min. Max. HAFT2 Median Mean Std. Dev.

Alfalfa Forage 0.1 

1 6 

0.0600 5.74 3.60 1.56 1.98 1.94 

0.3-0.4 3.40 11.6 9.70 6.06 7.71 4.99 

Alfalfa Hay 0.1 4.36 15.7 13.3 4.92 6.86 3.38 

0.3-0.4 10.1 45.2 41.1 17.1 23.1 14.4 

Alfalfa Seed 0.1 0.06 60.3 47.4 0.26 15.9 25.7 

0.3 0.09 2.05 1.58 0.41 0.700 0.760 1

Residue values were from the third cutting 

2

HAFT = Highest Average Field Trial. 

D. CONCLUSION 

Studies were conducted consistent with standard agricultural practices as per proposed 

experimental designs. Anomalous weather events were recorded at the WA*33, which 

experienced below normal temperature and higher than normal rainfall. These occurrences had 

no adverse impact on the study. An adjuvant was added to the spray mixture for all applications 

except ID17 for TRT 02 and TRT 03. 

The LC/MS/MS residue analytical methods used for determining diflubenzuron, CPU, and PCA 

in/on alfalfa forage, alfalfa hay and alfalfa seed were validated and adequate for data collection. 

Storage stability data indicated that residues were stable under the conditions that samples were 

held between harvest and analysis. Following three foliar applications of Dimilin 2L at 0.0314-

0.0351lb ai/A and 0.0934-0.0982 lb ai/A per application, the maximum combined diflubenzuron, 

CPU and PCA residues in/on alfalfa forage samples (3rd cutting) harvested at 1-day PHI, were 

5.74 ppm and 11.6 ppm, respectively. The maximum combined diflubenzuron, CPU and PCA 

residues in/on alfalfa hay samples (3rd cutting) harvested at 1-day PHI, were 15.71 ppm and 

45.15 ppm, respectively. The maximum combined diflubenzuron, CPU and PCA residues in/on 

alfalfa seed harvested at 1-day PHI, were 60.31 (low rate) and 2.05 (high rate). 

E. REFERENCES

US EPA DER (14-Sep-2006): MRID 46609501. Corley, J. (2005) Diflubenzuron: Magnitude of 

Page 77 of 100
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Crop Field Trial – Alfalfa 

PMRA Submission No. /DP Barcode D423328 /MRID No.49399502 Page 14 of 14

the Residue on Small Grain. Lab Project Number: 08024.02-PTR01. Unpublished study 

prepared by Interregional Research Project No. 4 (IR-4). 800 p. 

F. DOCUMENT TRACKING

RDI: T. Morton (6/20/2015) 

Petition Number(s): 4E8306 

DP Barcode(s): D423328 

PC Code: 108201 

Template Version June 2005.

Page 78 of 100
Di llubcnzuron/ I 0820 I /Chemtura Corporntion/400 

DACO 7.4.117.4.2/0PPTS 860.1500/0ECD llA 6.3.1, 6.3.2, 6.3.3 and ll!A 8.3.I, 8.3.2, 8.3.3 

Crop Field Trial/ Residue Decline - Carrot 

Primary Evaluator 

Peer Reviewer 

J Jesus Leyva 

Environmental Scientist, 

California DepartmeJt:>of Pesticide Regulation 

~~ r<a-#o 

Theresa Ratto, Ph.D., 

Senior Envirqnmental Scientist (Specialist), 

California Department of Pesticide Regulation 

Date: 3/ I 0/2015 

Date: 

Approved by Date: 6/ 1512015 

Thmston G. Morton, Chemist 

HED/RABJV (7509P) 

Sumitra Bose Biswas, Chemist 

HED/RABVJ (7509P) 

1lf7'57r 

~10·~ 

STUDY REPORTS: 

MRID No. 49399503. Kenneth S. Sarnoi l (2008) Diflubenzuron: Magnitude of the Residue on 

Carrot. Project Number: 08643 . Unpublished study prepared by The Interregional Research 

Project No. 4 (IR-4), 245 pages. 

EXECUTIVE SUMMARY: 

. The !R-4 has submitted field trial data for diflubcnzuron on carrot. Nine field trials were 

conducted in the United States during the 2008 growing season. Trials were conducted in North 

American free Trade Agreement (NAFT A) Growing Zones I 0 (CA, 4 trials), 2 (GA, 2 trials), 5 

(OH, I trial), 6 (TX, I trial), and 11 (WA, 1 trial). Each trial site consisted of one untreated plot 

and one treated plot. At each test location, two fol iar applications of the test substance (Oimilin 

2L) were made at 6-8 days re-treatment interval (RT!) to the treated plots at rates of 0.1 19-0. 129 

lb ai/A per application for a total rate of0.243-0.255 lb ai/A per season. No adjuvant or additive 

was added to spray mixtures for any of the applications. Carrot raw agricultural commodity 

(RAC) samples were harvested 6-7 days l:)fter the last application. At the CA88 trial, additional 

dupli cate samples were collected at 3, 10, and 14 clays after the last application. 

The harvested carrot RAC samples were analyzed for residues of diDubenzuron, 4-

chlorophcnylurea (CPU), and 4-chloroaniline (PCA) by liquid chromatography/tandem mass 

spectroscopy (LC/MS/MS) using modified methods derived from : "Difiubenzuron: Magnitude of 

the Residue in Small Grains," Janine E. Rose, Ph.D., Uniroyal Study No. 08024, PTRL Study 

No. I 129W, or "Oimilin 25W, Dimilin 80WG, and Dimilin 2L in Almonds: Magnitude of 

Residue Study:· Janine E. Rose, Ph.D., Uniroyal Study No. RP-98003. The methods were 

adequately validated in conj unction with the field sampk analyses. The lowest level of method 

validation (LLMV) for residues of diflubenzuron in/on carrot samples was 0.050 ppm and 0.005 

ppm for CPU and PCA. 

PMRA Submission No. /DP Barcodc 0423328 /MRID No. 49399503 Page I of 10 

Page 79 of 100
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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 2 of 10

Following two foliar applications of Dimilin 2L at 6-8 days RTI, combined residues of 

diflubenzuron, CPU and PCA were <0.06-0.08 ppm. In the decline trial, combined residues 

were 0.06 ppm at pre-harvest intervals (PHIs) of 3, 7, 10 and 14 days. 

A freezer storage stability study was conducted in conjunction with this study. Diflubenzuron 

residues were stable in/on carrots when stored frozen for up to 1114 days. 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS: 

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document [DP Barcode Dxxxxxx]. 

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. This study meets current GLP Requirements of 40 CFR Part 160, 

with the following deviations, which do not affect the conclusions presented in this report: 

1. Weather/irrigation and soil characterization at the field sites. 

2. Test site history at the field sites. 

3. Cultural practices dating back to harvest of the previous crop, and maintenance fertilizer 

and pesticide applications during the field trial year. 

4. Environmental monitoring devices for test substance storage in the OH*04 field trial. 

5. The pH meter used to measure the acidity of the carrier in the field trials. Except in the 

CA*89 and CA*90 trials. 

6. Residue sample weighing equipment in the field trials, except in the OH*04 trial. 

7. The reference standards for diflubenzuron and PCA were not characterized in accordance 

with GLP standards prior to their use at the Smithers Viscient laboratory in this study. 

These standards were subsequently characterized under GLP standards at Smithers 

Viscient, and the results confirmed the respective purities claimed by the supplier. 

A. BACKGROUND INFORMATION 

Diflubenzuron is an insecticide/acaricide (insect growth regulator) that behaves as a chitin 

inhibitor to suppress the growth of many leaf-eating larvae, mosquito larvae, aquatic midges, rust 

mite, boll weevil, and flies. Diflubenzuron was first registered in the United States in 1979 for 

use as an insecticide. The Agency issued a Registration Standard for diflubenzuron in 

Page 80 of 100
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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 3 of 10

September, 1985, (NTIS #PB86-176500). Diflubenzuron was also the subject of a Residue 

Chemistry Chapter dated 11/16/84, an Addendum to the Registration Standard dated 12/4/84, 

and a Reregistration Standard Update dated 6/21/91. The Reregistration Eligibility Decision 

(RED) for diflubenzuron was issued in August, 1997 (EPA 738-R-97-008). Tolerances for 

residues of diflubenzuron are established under 40 CFR §180.377 [US EPA Data Evaluation 

Record (DER), 11/14/2006]. 

TABLE A.1. Test Compound Nomenclature.

Diflubenzuron 

H

N

O

H

N

O

F

F

Cl

Common name Diflubenzuron 

Company experimental name DU 112307 

IUPAC name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS # 35367-38-5 

End-use product/(EP) 2 lb/gal FIC formulation; Dimilin® 2L (EPA Reg. No. 400-461) 

Regulated Metabolite 

O

N

H

Cl

2NH

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite 

Cl

2NH

Common Name 4-chloroaniline (PCA) 

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

Melting point/range 210-230°C 

(US EPA DER, 11/14/2006) 

pH Not available 

Density (22°C) Not available 

Water solubility (25°C) 0.08 mg/L 

Solvent solubility (25°C) (ppm) 

6.5 x 103 Acetone 

2 x 103

 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105 Dimethylsulfoxide 

1 x 103

 Methanol 

6 x 102

 Dichloromethane 

Vapor pressure at 25°C 1.2x10-4mPA (9.0x10-10 mmHg) 

Dissociation constant (pKa) Not available 

Octanol/water partition coefficient Log(KOW) 3.89 

Page 81 of 100
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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 4 of 10

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

UV/visible absorption spectrum Not available 

B. EXPERIMENTAL DESIGN

B.1. Study Site Information 

TABLE B.1.1 Trial Site Conditions.

Trial Identification (City, State/Year) Soil characteristics1

Type %OM pH CEC (meq/g) 

CA87 (Holtville, CA/2008) Silty Clay Loam NR2 7.8 25.8-26.6 

CA88 (Parlier, CA/2008) Sandy Loam 0.75 6.7 7.5 

CA*89 (Salinas, CA/2008) Loam 1.7 6.5 14 

CA*90 (Salinas, CA/2008) Loam 1.9 7.6 18 

GA*04 (Tifton, GA/2008) Sand 0.42 5.82 2.73 

GA*05 (Tifton, GA/2008) Sand 0.42 5.82 2.73 

OH*04 (Willard, OH/2008) Loam 63.5 5.7 42.1 

TX*35 (Weslaco, TX/2008) Sandy Clay Loam 1.65 7.9 NR 

WA*17 (Moxee, WA/2008) Silt Loam 0.91 7.2 15.1 1

OM = Organic matter, CEC = Cation-exchange capacity. These parameters are optional except in cases where their value affects the use pattern 

for the chemical. 

2

Not Reported 

The actual temperature recordings were within average historical values for the residue study 

period. The actual rainfall average was within the historical rainfall average except at GA*04 

and GA*05 field trials where rainfall was below normal. Irrigation was used to supplement as 

needed. 

TABLE B.1.2. Study Use Pattern

Location 

(City, State/Year) 

Trial ID 

EP1 Application Tank Mix/ 

Method/Timing Volume Adjuvants

GPA2

Rate 

(lb ai/A) 

RTI 

(days) 

Total Rate 

(lb ai/A) 

(Holtville, CA/2008) 

CA87 

Dimilin 

2L 

1. Foliar Broadcast/Early maturity 25 0.127 - 0.25 None 

2. Foliar Broadcast/Mature 24 0.123 7 

(Parlier, CA/2008) 

CA88 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 31 0.127 - 0.253 None 

2. Foliar Broadcast/Vegetative 31 0.126 7 

(Salinas, CA/2008) 

CA*89 

Dimilin 

2L 

1. Foliar Broadcast/ 

1/2-3/4” diameter roots 

39 0.125 - 0.251 None 

2. Foliar Broadcast/ 

3/4-1” diameter roots 

48 0.126 6 

(Salinas, CA/2008) 

CA*90 

Dimilin 

2L 

1. Foliar Broadcast/1/2-1” diameter 

roots 

44 0.126 - 0.255 None 

2. Foliar Broadcast/1/2-1” diameter 

roots 

47 0.129 6 

(Tifton, GA/2008) 

GA*04 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 32 0.126 - 0.254 None 

2. Foliar Broadcast/Vegetative 33 0.128 7 

(Tifton, GA/2008) 

GA*05 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 33 0.128 - 0.254 None 

2. Foliar Broadcast/Vegetative 32 0.126 7 

(Willard, OH/2008) 

OH*04 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 22 0.124 - 0.243 None 

2. Foliar Broadcast/Vegetative 22 0.119 7 

(Weslaco, TX/2008) Dimilin 1. Foliar Broadcast/Roots Forming 39 0.126 - 0.250 None 

Page 82 of 100
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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 5 of 10

TABLE B.1.2. Study Use Pattern

Location 

(City, State/Year) 

Trial ID 

EP1 Application Tank Mix/ 

Method/Timing Volume Adjuvants

GPA2

Rate 

(lb ai/A) 

RTI 

(days) 

Total Rate 

(lb ai/A) 

TX*35 2L 2. Foliar Broadcast/Roots Formed 39 0.124 7 

(Moxee, WA/2008) 

WA*17 

Dimilin 

2L 

1. Foliar Broadcast/Vegetative 40 0.124 - 0.247 None 

2. Foliar Broadcast/Vegetative 40 0.123 8 1

EP = End-use Product 

2

GPA = Gallons per acre 

TABLE B.1.3. Trial Numbers and Geographical Locations 

NAFTA Growing Zones Carrot 

Submitted Requested 

Canada US 

1 

1A 

2 21 

3 1 

4 

5 1 1 

5A 

5B 

6 1 1 

7 

7A 

8 

9 

10 4 4 

11 1 1 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total 9 8 1

Region 2 trials in this study were conducted in southern Georgia, near the border with Region 3. 

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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 6 of 10

B.2. Sample Handling and Preparation

Representative carrot RAC samples were harvested at all field trials 6-7 days after the last 

application. Duplicate carrot samples were collected from each control and treated plot. Tops 

were removed in the field and soil was shaken and lightly brushed off from the roots. At the 

CA*89 and CA*90 field sites, soil was washed off by rinsing the roots in cool water. Damaged 

roots were discarded. The samples were shipped frozen to the USDA-ARS (Beltsville, MD) 

analytical laboratory either by ACDS freezer truck or overnight air express packed in dry ice. 

All samples arrived frozen and intact at the analytical laboratory. The samples were checked in, 

ground with dry ice and stored frozen until extraction and analysis. Samples were analyzed for 

the parent compound, diflubenzuron, at the Beltsville, ARS facility. Prior to the analysis for the 

metabolites, the Beltsville facility was closed by USDA-ARS, and no further work was done on 

this study. The residue and fortified samples were transferred via ACDS freezer truck to the 

USDA-ARS laboratory in Tifton, Georgia, for storage and subsequently shipped by ACDS 

freezer truck to Smithers Viscient laboratory, Wareham, MA for complete residue analyses. All 

samples arrived frozen and intact and were stored frozen (generally <-20 oC). 

B.3. Analytical Methodology

Residues of diflubenzuron, CPU, and PCA in/on carrot were quantified by LC/MS/MS using 

methods derived from “Diflubenzuron: Magnitude of the Residue in Small Grains”, Janine E. 

Rose, Ph.D., Uniroyal Study No. 08024, PTRL Study No. 1129W, or “Dimilin 25W, Dimilin 

80WG, and Dimilin 2L in Almonds: Magnitude of Residue Study”, Janine E. Rose, Ph.D., 

Uniroyal Study No. RP-98003, September 13, 1999. 

For analysis of diflubenzuron and CPU, the sample was homogenized, centrifuged, and then 

extracted three times using acetonitrile as the extraction solvent. The acetonitrile layers were 

collected and taken to a final volume of 80.0 mL with acetonitrile. For 4-chorophenyl urea, the 

sample was dried using a gentle stream of nitrogen, vortexed for 30 seconds after the addition of 

an aliquot of 10:90 acetonitrile:purified reagent water (v:v) and sonicated for five minutes. The 

sample was further diluted into the calibration standard range with purified reagent water. If 

particles were present, the sample was centrifuged at 13,000 rpm for five minutes prior to 

analysis by LC/MS/MS. The calculated limit of detection (LOD) and limit of quantitation 

(LOQ) for diflubenzuron residues in/on carrot RAC samples were 0.01040 ppm and 0.03120 

ppm, respectively. The calculated LOD and LOQ for CPU residues in/on carrot RAC samples 

were 0.00128 ppm and 0.00384 ppm, respectively. The LLMV for residues of diflubenzuron and 

CPU in/on carrot samples were 0.05 ppm and 0.005 ppm, respectively. 

The processed sample matrix was fortified with the internal standard ([13C6]4-chloroaniline) for 

analysis of PCA. The sample was vortexed then allowed to settle with the cap off for five 

minutes. Residues were extracted using 0.1N hydrochloric acid solution (in purified reagent 

water) and shaken at 60 °C for 30 minutes, brought to room temperature in a cold water bath, 

then centrifuged. The supernatant was then filtered and the remaining pellet was extracted twice 

more. Both extractions were collected and taken to a final volume of 100 mL with 0.1N 

hydrochloric acid solution. Residues were analyzed by LC/MS/MS. The calculated LOD and 

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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 7 of 10

LOQ for PCA residues in/on carrot RAC samples were 0.00294 ppm and 0.00883 ppm, 

respectively. The LLMV for residues of PCA in/on carrot samples was 0.005 ppm. 

The methods were validated prior to sample analysis using control carrot samples fortified with 

diflubenzuron, CPU or PCA at 0.005-0.5 ppm. 

C. RESULTS AND DISCUSSION 

The provided analytical methods were adequate for data collection. Recovery data for control 

samples fortified with diflubenzuron, CPU, and PCA and analyzed both prior to, and 

concurrently with, field-treated samples are summarized in Table C.1. Fortification levels 

ranged from 0.005 to 0.5 ppm. Method validation recoveries fell within the acceptable range of 

70% to 120% for diflubenzuron, CPU, and PCA on carrot. No interferences were noted in 

control samples. 

The maximum storage intervals for field-treated samples in this study were 1248 days for 

diflubenzuron and CPU and 1263 days for PCA (Table C.2). Storage stability samples were 

separately fortified with diflubenzuron (0.5 ppm), CPU (0.05 ppm) and PCA (0.05 ppm) soon 

after the receipt of the samples by the Beltsville analytical laboratory. The storage stability 

samples were held in frozen storage under similar conditions to the field generated samples. 

The data indicates that diflubenzuron and CPU were stable under the conditions which the 

samples were held between harvest and analysis, but PCA may have degraded by approximately 

90%. The consistency of the stability results for PCA suggests the possibility that the 

fortifications may have been made at 10% of the reported level (Table C.2.2). 

Following two foliar applications of Dimilin 2L at 6-8 days RTI, combined residues of 

diflubenzuron, CPU and PCA were 0.06-0.08 ppm. In the decline trial, combined residues were 

0.06 ppm at PHIs of 3, 7, 10 and 14 days. Residues of diflubenzuron (0.0676 ppm) were found 

in one sample harvested from the GA*04 trial at 6-7 days after the last application. In all other 

trials, the residue levels of diflubenzuron, CPU and PCA were <LLMV. In the decline trial, no 

residues above the LOQ for the analytes were found, so no inferences can be drawn regarding 

the degradation of diflubenzuron and its metabolites (Table C.3). 

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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 8 of 10

TABLE C.1. Summary of Concurrent and Method Recoveries of Diflubenzuron from Carrot

Analyte Matrix Spike Level 

(ppm) Sample Size (n) Recoveries (%) Mean ± Std Dev 

(%) 

Concurrent 

Diflubenzuron 

Carrot 

0.05-0.5 11 85, 90, 93, 100, 100, 102, 103, 

104, 105, 106, 109 100  7 

CPU 0.005-0.05 11 91, 92, 94, 98, 112, 105, 107, 

107, 111, 111, 115 104  9 

PCA1 0.005-0.05 17 

45, 47, 98, 99, 105, 105, 106, 

107, 108, 109, 109, 111, 111, 

112, 112, 113, 116 

101  21 

Method Validation 

Diflubenzuron 

Carrot 

0.05-0.5 6 92, 93, 94, 98, 103, 103 97  5 

CPU 0.005-0.05 6 92, 93, 98, 102, 106, 103, 99  6 

PCA 0.005-0.05 6 107, 107, 111, 111, 114, 116 111  4 1

45% and 47% recoveries were described as being most likely the result of a “processing/fortification error” 

TABLE C.2. Summary of Storage Conditions

Matrix (RAC) Storage Temperature (°C) Actual Storage Duration 

(days) 

Interval of Demonstrated 

Storage Stability (days) 

Carrot <-20 1248-1263 1108-1129 

TABLE C.2.2 Stability of Diflubenzuron and its Metabolites in Frozen Carrot 

Matrix Analyte Spike Level 

(ppm) 

Storage 

Interval 

(Days) 

Freshly Fortified 

Recoveries (%) 

[Average] 

Stored Sample 

Recoveries (%) 

[Average]

Average 

Corrected Stored 

Recovery (%)1 

Carrot 

(Roots) 

Diflubenzuron 0.5 1242-1248 102, 109 [106] 91, 95, 104 [97] 92 

CPU 0.05 1242-1248 107, 111 [109] 101, 107, 107, 88, 109, 

113 [104] 95 

PCA1 0.05 1255-1263 98, 99, 105 [101] 12, 10, 10, 8, 7, 8 [9] 9 

1

The consistency of the stability results for PCA suggests the possibility that the fortifications may have been made at 10% of the reported level. 

TABLE C.3. Residue Data from Carrot Field Trials with Diflubenzuron

Trial ID 

(City, State/ Year) Zone Crop/Variety Commodity or Matrix 

Total Rate 

(lb ai/A) 

PHI 

(days)

Diflubenzuron

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

 Combined 

Residues 

(ppm)1

CA87 (Holtville, 

CA/2008) 10 Carrot/ Danvers 126 Root 0.25 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA88 (Parlier, CA 

/2008) 10 Carrot/ Danvers 126 Root 0.253 

3 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

10 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

14 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA*89 (Salinas, CA 

/2008) 10 Carrot/ Danvers 126 Root 0.251 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

CA*90 (Salinas, CA 

/2008) 10 Carrot/ 

Danvers 126 Root 0.255 6 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

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Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 9 of 10

TABLE C.3. Residue Data from Carrot Field Trials with Diflubenzuron

Trial ID 

(City, State/ Year) Zone Crop/Variety Commodity or Matrix 

Total Rate 

(lb ai/A) 

PHI 

(days)

Diflubenzuron

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

 Combined 

Residues 

(ppm)1

GA*04 (Tifton, GA 

/2008) 2 Carrot/ 

Chantenay Red Root 0.254 6 0.0676 <0.005 <0.005 0.08 

<0.05 <0.005 <0.005 0.06 

GA*05 (Tifton, GA 

/2008) 2 Carrot/ Danvers Root 0.254 6 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

OH*04 (Willard, OH 

/2008) 5 Carrot/ 

Maverick Root 0.243 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

TX*35 (Weslaco, TX 

/2008) 6 Carrot/ 

Nikki (Nantes) Root 0.250 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 

WA*17 (Moxee, WA 

/2008) 11 Carrot/ Ya Ya 1 Root 0.247 7 <0.05 <0.005 <0.005 0.06 

<0.05 <0.005 <0.005 0.06 1

To determine combined residues (Diflubenzuron + CPU + PCA), residues <0.05 ppm and <0.005 ppm were assigned values of 0.05 ppm and 

0.005 ppm, respectively. 

TABLE C.4. Summary of Residue Data from Crop Field Trials with Diflubenzuron

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues (Diflubenzuron + CPU + PCA) [ppm] 

n Min. Max. HAFT1 Median Mean2 Std. Dev.

Carrot 0.243-0.255 

3 2 0.06 0.06 0.06 - - - 

6-7 18 0.06 0.08 0.07 0.06 0.06 0.004 

10 2 0.06 0.06 0.06 - - - 

14 2 0.06 0.06 0.06 - - - 1

HAFT = Highest Average Field Trial 

D. CONCLUSION 

Studies were conducted consistent with standard agricultural practices as per proposed 

experimental designs. No anomalous weather events were recorded, except at the GA*04 and 

GA*05 sites, which experienced below normal rainfall that had no adverse impact on the study. 

The LC/MS/MS residue analytical methods used for determining diflubenzuron, CPU, and PCA 

in/on carrot were validated and adequate for data collection. Storage stability data indicated that 

residues were stable under the conditions that samples were held between harvest and analysis. 

The maximum combined diflubenzuron, CPU and PCA residues in/on carrot samples harvested 

6-7 days following two foliar applications of Dimilin 2L at 0.119-0.129 lb ai/A per application, 

without the use of an adjuvant, were 0.07 ppm. In the decline trial, no residues above the LOQ 

for diflubenzuron, CPU, or PCA were found, so no inferences can be drawn regarding the 

degradation of diflubenzuron and its metabolites. 

E. REFERENCES

US EPA DER (14-Sep-2006): MRID 46609501. Corley, J. (2005) Diflubenzuron: Magnitude of 

the Residue on Small Grain. Lab Project Number: 08024.02-PTR01. Unpublished study 

prepared by Interregional Research Project No. 4 (IR-4). 800 p. 

F. DOCUMENT TRACKING

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 

Crop Field Trial/ Residue Decline - Carrot 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399503 Page 10 of 10

RDI: T. Morton (6/20/2015) 

Petition Number(s): 4E8306 

DP Barcode(s): D423328 

PC Code: 108201 

Template Version June 2005.

Page 88 of 100
----·- ··- ·-·---- - ..... 

J:I DiOubcnzuron/I 0820 I/Chemtura Corporation/400 

~= i}'1 i! DACO 7.4.117.4.2/0PPTS 860.1500/0ECD llA 6.3.1 , 6.3.2, o.3.3 and I !IA 8.3.1 , S.3.2, 8.3.3 

_ Crop Field Trinl/ Residue Decline - Pench nncl Plum · · 

Primary Evaluator --J" A 

~-""\,..~./"':' _ _ J Jesus Leyva ·-i 

Peer Reviewer 

Environmental Scientist, 

California Department o 

Theresa Rntto, Ph.D., 

Senior vir~:mmental Scientist (Specialist), 

California Dcpartmenl of Pesticide Regulation 

Date: 3/10/20 I 5 

Date: 6/15/2015 

Thurston G. Morton, Chemist · ~~--·· HED/RABIV (7509P) I. 

Approved by 

Sumitra Bose Biswas, Chemist / __ __ Tf__,A lb~ HED/RABVI (7509P) . ~,, ............ 

STUDY REPORTS: 

MRfD No. 49399504. Will iam P. Barney (2013) Diflubenzuron: Magnitude of the Residue on 

Peach & Plum. Lab Project Number: 08644. Unpublished study prepared by The fnterregional 

Research Project Ko. 4 (IR-4). 364 pages. 

EXECUTIVE SUMMARY: 

The IR-4 has submitted field trial da1a for ditlubenzuron on peach and plum. Twelve field trials 

. were conducted in the Uni1cd States durLng 2009 growLng season. Trials were conducted in 

North American Free Trade Agreement (NArT A) Growing Zones l 0 (CA, 6 trials), 2 (NC and 

NJ, 3 trials), 4 (AR, I 1rial)1 5 (Ml, I trial), and J I (WA, 1 trial). 

l\L each test locAtion, which consisted of one untreated plot nnd one treated plot, two air-blast 

applications of the test substance (Di mil in 2L) were made post bloom 13-15 days re-treatment 

interval (RTJ) at rates of 0.235-0.259 lb ail A per applkation to ·the treated plots. An adjuvant 

was added to each spray mixture. Peach and plum raw agricultural commodity (RAC) samples 

were harvested I 0-16 days after the last application. At the CA4 I trial, duplicate samples were· 

collected 0, 7 and 2 J dnys nfter the last application. At the CA43 trial, duplicate samples of 

lreated and untreated plums harvested 13 clays after the last application wen~ collected at1er 

drying. 

Peach and plum samples were analyzed for residues of diflubenzuron, 4-ch!orophenylurea 

(CPU), and 4-chloroanilinc (PCA) by liquid chromatography/tandem mass spectroscopy 

(LC/MS/MS) using a modified method derived from, "Dimilin 25W, Dimilin 80WG, and 

Dimilin 2L in Almonds: Magnitude of Residue Study", Janine E. Rose, Ph.D., Uniroynl Study 

No. RP-98003. The method was adequately validated In conjunction with the field sample 

analyses. The lowest level of method validalion (LLMV) for residues of diflubcnzuron in/on 

peach and plum samples was 0.05 ppm and 0.005 ppm for CPU and ~CA. 

PMRA Submission No. /DP Barcode 0423328 /MRID No. 49399504 Pnge I of l 2 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 2 of 12

Following two foliar applications of Dimilin 2L at 14 days RTI, combined residues of 

diflubenzuron, CPU and PCA were 0.060-0.48 ppm in peaches without pits harvested at 14-16 

days pre-harvest interval (PHI) and 0.060-0.12 ppm in plums without pits harvested at 10-14 

days PHI. Combined residues of diflubenzuron, CPU and PCA in dried plums were 0.20 ppm. 

In the decline trial, combined residues declined from 0.24 ppm at 0-day PHI to 0.08 ppm at 21-

days PHI. 

A freezer storage stability study was conducted in conjunction with this study. Samples of plum 

and peach were stored for up to 911 days before analysis. 

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS: 

Under the conditions and parameters used in the study, the field trial residue data are classified 

as scientifically acceptable. The acceptability of this study for regulatory purposes is addressed 

in the forthcoming U.S. EPA Residue Chemistry Summary Document [DP Barcode Dxxxxxx]. 

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and Data Confidentiality 

statements were provided. This study meets current GLP Requirements of 40 CFR Part 160, 

with the following deviations, which do not affect the conclusions presented in this report: 

1. Supporting data such as weather/irrigation, soil characteristics records; test site history 

and cultural practices; and maintenance fertilizers and pesticide data were not collected in 

strict adherence to 40 CFR 160 guidelines. 

2. At all trails except NC07 and WA18, the scale used for obtaining field sample weights 

was not maintained according to GLP standards. 

3. At NJ04 and NJ05 field trials the test substance was received and logged in before 

facility SOPs were in place. 

4. The reference standards diflubenzuron and 4-chloroaniline were used in the study for 

method validation prior to their GLP characterization. 

5. The test substance and 4-chlorophenylurea reference substance was characterized by 

Chemtura Canada Co./Cie, Guelph Technology Centre, PO Box 1120, 120 Huron St. , 

Guelph, Ontario, Canada. Therefore, the test substance was not characterized in 

accordance with 160.135 (a) (b), but was characterized in accordance with OECD 

guidelines, which are accepted by US EPA in a Memorandum of Understanding. 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 3 of 12

A. BACKGROUND INFORMATION

Diflubenzuron is an insecticide/acaricide (insect growth regulator) that behaves as a chitin 

inhibitor to suppress the growth of many leaf-eating larvae, mosquito larvae, aquatic midges, rust 

mite, boll weevil, and flies. Diflubenzuron was first registered in the United States in 1979 for 

use as an insecticide. The Agency issued a Registration Standard for diflubenzuron in 

September, 1985, (NTIS #PB86-176500). Diflubenzuron was also the subject of a Residue 

Chemistry Chapter dated 11/16/84, an Addendum to the Registration Standard dated 12/4/84, 

and a Reregistration Standard Update dated 6/21/91. The Reregistration Eligibility Decision 

(RED) for diflubenzuron was issued in August, 1997 (EPA 738-R-97-008). Tolerances for 

residues of diflubenzuron are established under 40 CFR §180.377 [US EPA Data Evaluation 

Record (DER) 11/14/2006]. 

TABLE A.1. Test Compound Nomenclature.

Diflubenzuron 

H

N

O

H

N

O

F

F

Cl

Common name Diflubenzuron 

Company experimental name DU 112307 

IUPAC name 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea 

CAS name N-[[(4-chlorophenyl)amino]carbonyl]-2,6-difluorobenzamide 

CAS # 35367-38-5 

End-use product/(EP) Dimilin 2L 

Regulated Metabolite 

O

N

H

Cl

2

NH

Common name 4-chlorophenylurea (CPU) 

Regulated Metabolite 

Cl

2

NH

Common Name 4-chloroaniline (PCA) 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 4 of 12

TABLE A.2. Physicochemical Properties of the Technical Grade Test Compound: Diflubenzuron. 

Parameter Value Reference 

Melting point/range 210-230°C (US EPA DER, 11/14/2006) 

pH Not available 

Density Not available 

Water solubility (25°C) 0.08 mg/L 

Solvent solubility (25°C) (ppm) 6.5 x 103 Acetone 

2 x 103

 Acetonitrile 

2.4 x 104 Dioxane 

1.04 x 105 Dimethylformamide 

1.2 x 105 Dimethylsulfoxide 

1 x 103

 Methanol 

6 x 102

 Dichloromethane 

Vapor pressure at 25°C 1.2x10-4 mPA (9.0x10-10 mmHg) 

Dissociation constant (pKa) Not available 

Octanol/water partition coefficient Log(KOW) 3.89 

UV/visible absorption spectrum Not available 

B. EXPERIMENTAL DESIGN 

B.1. Study Site Information 

TABLE B.1.1 Trial Site Conditions.

Trial Identification (City, State/Year) Soil characteristics1

Type %OM pH CEC (meq/g) 

AR05 (Clarksville, AR/2009) Silt Loam - 6.4 9 

CA38 (Gridley, CA/2009) Loam 1.89 6.1 26.4 

CA39 (Parlier, CA/2009) Fine Sandy Loam 0.75 6.7 7.5 

CA40 (Parlier, CA/2009) Fine Sandy Loam 0.75 6.7 7.5 

CA41 (Parlier, CA/2009) Fine Sandy Loam 0.75 6.7 7.5 

CA42 (Parlier, CA/2009) Fine Sandy Loam 0.75 6.7 7.5 

CA43 (Gridley, CA/2009) Loam 2.14 5.6 24.8 

MI17 (Fennville, MI/2009) Loamy Sand 1.2 5 4.4 

NC07 (Jackson Springs/2009) Sand 2.1 6.9 5.2 

NJ04 (Cream Ridge, NJ/2009) Sandy Loam 2.8 5.1 13.6 

NJ05 (Cream Ridge, NJ/2009) Sandy Loam 2.2 5.4 12.1 

WA18 (Wapato, WA/2009) Sandy Clay Loam 5.35 5.46 4.28 1

OM = Organic matter, CEC = Cation-exchange capacity. These parameters are optional except in cases where their value affects the use pattern 

for the chemical. 

The actual temperature recordings and rainfall average were within average historical values for 

the residue study period, except at the NJ04 and NJ05 field sites, where temperature and rainfall 

varied. Irrigation was used to supplement as needed. 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 5 of 12

TABLE B.1.2 Study Use Pattern.

Location 

(City, State/ Year) 

Trial ID 

EP1

Application Tank Mix/ 

Method/Timing Adjuvants Volume

(Gallons/A) 

Rate 

(lb ai/A) 

RTI 

(days) 

Total Rate 

(lb ai/A) 

(Clarksville, AR/ 

2009) AR052

Dimilin 

2L 

1. Airblast/Fruiting 127 0.235 - 0.494 Agri-Dex 2. Airblast/Fruiting 116 0.259 14 

(Gridley, CA/ 

2009) CA383

Dimilin 

2L 

1. Airblast/Fruiting 98 0.243 - 0.484 Crop Oil 2. Airblast/Fruiting 97 0.241 14 

(Parlier, CA/ 

2009) CA392

Dimilin 

2L 

1. Airblast/Fruiting 146 0.252 - 0.503 Agri-Dex 2. Airblast/Fruiting 146 0.251 14 

(Parlier, CA/ 

2009) CA403

Dimilin 

2L 

1. Airblast/Fruiting 80 0.250 - 0.502 Agri-Dex 2. Airblast/Fruiting 81 0.252 14 

(Parlier, CA/ 

2009) CA412

Dimilin 

2L 

1. Airblast/Fruiting 63 0.256 - 0.508 Agri-Dex 2. Airblast/Fruiting 63 0.252 14 

(Parlier, CA/ 

2009) CA423

Dimilin 

2L 

1. Airblast/Fruiting 101 0.253 - 0.505 Agri-Dex 2. Airblast/Fruiting 101 0.252 14 

(Parlier, CA/ 

2009) CA433

Dimilin 

2L 

1. Airblast/Fruiting 98 0.244 - 0.484 Crop Oil 2. Airblast/Fruiting 96 0.240 14 

(Fennville, MI/ 

2009) MI172

Dimilin 

2L 

1. Airblast/Fruiting 102 0.252 - 0.502 Damoil 2. Airblast/Fruiting 101 0.250 15 

(Jackson Springs 

/2009) NC072

Dimilin 

2L 

1. Airblast/Early Fruiting 81 0.252 - 0.504 Herbimax 2. Airblast/Fruiting 80 0.252 14 

(Cream Ridge, 

NJ/2009) NJ042

Dimilin 

2L 

1. Airblast/Fruiting 132 0.257 - 0.510 Agri-Dex 2. Airblast/Fruiting 120 0.253 13 

Cream Ridge, 

NJ/2009) NJ052

Dimilin 

2L 

1. Airblast/Fruiting 119 0.250 - 0.499 Agri-Dex 2. Airblast/Fruiting 121 0.249 14 

(Wapato, WA/ 

2009) WA183

Dimilin 

2L 

1. Airblast/Fruiting 124 0.248 - 0.499 JMS Stylet-Oil 2. Airblast/Fruiting 126 0.251 14 1

EP = End-use Product

2

Peach field trials 

3

Plum field trials

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DACO 7.4.1/7.4.2/OPPTS 860.1500/OECD IIA 6.3.1, 6.3.2, 6.3.3 and IIIA 8.3.1, 8.3.2, 8.3.3 

Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 6 of 12

TABLE B.1.3. Trial Numbers and Geographical Locations. 

NAFTA 

Growing 

Zones 

Peach Plum 

Submitted Requested1

Submitted Requested1

Canada US Canada US 

1 1 

1A 

2 3 4 

3 

4 1 1 

5 1 1 1 

5A 

5B 

6 1 

7 

7A 

8 

9 

10 2 4 4 5 

11 1 1 

12 1 

13 

14 

15 

16 

17 

18 

19 

20 

21 

Total 7 12 5 8 1

The registrant conducted a study in 2005 that included 5 peach trials and 3 plum trials. This study completes the requirements for peach and 

plum. 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 7 of 12

B.2. Sample Handling and Preparation

Representative samples of peach and plum were harvested 10-16 days after the last application at 

all field sites and began in the untreated control plot and ended in the treated plot. At the CA41 

trial, additional duplicate samples were collected 0, 7, and 21 days after the last application. At 

the CA43 trial, duplicate samples of treated and untreated plums harvested 13 days after the last 

application were collected after drying. Peaches and plums were halved and pits removed. 

Pitted fruit were placed in sample bags and transported to freezers. The samples were shipped 

frozen to the USDA-ARS analytical laboratory in Beltsville, MD by ACDS freezer truck. All 

samples arrived frozen and intact at the analytical laboratory. The samples were checked-in, 

ground with dry ice, and then stored frozen. The field samples and storage stability samples 

were analyzed for diflubenzuron. Due to closure of the laboratory, the samples were temporarily 

shipped from Beltsville, MD to the USDA-ARS laboratory in Tifton, GA for storage. Samples 

were then shipped to Smithers Viscient analytical laboratory for analysis. Samples were stored 

frozen (generally <-20 oC). The field samples were analyzed for diflubenzuron, CPU and PCA. 

Storage stability samples were analyzed to ensure stability of the analytes during shipping. 

B.3. Analytical Methodology

Peach and plum samples were analyzed for residues of diflubenzuron, CPU, and PCA by 

LC/MS/MS using a modified method derived from, “Dimilin 25W, Dimilin 80WG, and Dimilin 

2L in Almonds: Magnitude of Residue Study”, Janine E. Rose, Ph.D., Uniroyal Study No. RP98003. The method was adequately validated in conjunction with the field sample analyses. 

At the Beltsville, MD laboratory, for analysis of diflubenzuron, samples of peach and plum were 

extracted using acetonitrile. After blending, it was decanted into a graduated cylinder, 

partitioned with hexane, concentrated, and cleaned up on a C18 solid phase extraction (SPE) 

column. The residues were quantified by LC/MS/MS detection. 

At the Smithers Viscient laboratory, for analysis of diflubenzuron and CPU, samples of peach 

and plum were homogenized, centrifuged, and extracted three times with acetonitrile. The 

acetonitrile layers were collected and taken to a final volume of 80 mL with acetonitrile. For 

CPU, subsamples of peach and plum were dried using a gentle stream of nitrogen, vortexed for 

30 seconds after the addition of an aliquot of 10:90 acetonitrile:purified reagent water (v:v), and 

sonicated for five minutes. The diflubenzuron and CPU extracts were further diluted into the 

calibration standard range with purified reagent water. If particles were present, samples were 

centrifuged at 13,000 rpm for five minutes prior to analysis by LC/MS/MS. The calculated limit 

of detection (LOD) and limit of quantitation (LOQ) for diflubenzuron residues in/on peaches 

were 0.01442 ppm and 0.04326 ppm, respectively; 0.01521 ppm and 0.04564 ppm in plums, 

respectively; and 0.00795 ppm and 0.02385 ppm in dried plums, respectively. The calculated 

LOD and LOQ for CPU residues in/on peaches were 0.00114 ppm and 0.00342 ppm, 

respectively; and 0.00083 ppm and 0.00248 ppm in plums, respectively. The LLMV for residues 

of diflubenzuron and CPU in/on peach and plum samples were 0.05 ppm and 0.005 ppm, 

respectively. 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 8 of 12

For PCA, 5.0 g of sample matrix was used for the peach and plum samples with the exception 

that for the plum samples, the processed sample matrix was fortified with the internal standard 

([13C6]4-chloroaniline) followed by vortexing then allowing the sample bottle to remain open for 

5 minutes. Peach and plum samples were extracted with 0.1N hydrochloric acid and shaken at 

60 °C for 30 minutes, brought to room temperature in a cold water bath, then centrifuged. The 

supernatant was then filtered and the remaining pellet was extracted twice more with 0.1N 

hydrochloric acid, collecting each extraction and taken to a final volume of 100mL with 

hydrochloric acid. The peach and plum samples were further diluted into the calibration 

standard range with 10 mM ammonium formate in purified reagent water. The calculated LOD 

and LOQ for PCA residues in/on peaches were 0.00158 ppm and 0.00474 ppm, respectively and 

0.00058 ppm and 0.00174 ppm in plums, respectively. The LLMV for residues of PCA in/on 

peach and plum samples was 0.005 ppm. 

The methods were validated prior to sample analysis using control peach and plum samples 

fortified with diflubenzuron, CPU or PCA at 0.005-0.5 ppm. 

C. RESULTS AND DISCUSSION 

The provided analytical methods were adequate for data collection. Recovery data for control 

samples fortified with diflubenzuron, CPU, and PCA and analyzed both prior to, and 

concurrently with, field-treated samples are summarized in Table C.1. Fortification levels 

ranged from 0.005 to 0.5 ppm. Method validation recoveries fell within the acceptable range of 

70% to 120% for diflubenzuron, CPU, and PCA on peach and plum. No quantifiable residues of 

diflubenzuron, CPU or PCA were detected in untreated control peach or plum samples. 

Following two foliar applications of Dimilin 2L at 14 days RTI, combined residues of 

diflubenzuron, CPU and PCA were 0.06-0.48 ppm in peaches harvested at 14-16 days PHI and 

0.06-0.12 ppm in plums harvested at 10-14 days PHI. Combined residues of diflubenzuron, CPU 

and PCA in dried plum were 0.20 ppm. In the decline trial, combined residues declined from 

0.24 ppm at 0-day PHI to 0.08 ppm at 21-days PHI. 

Storage stability samples fortified with diflubenzuron at 0.5 ppm and held in frozen storage 

under similar conditions to the field generated samples at the USDA-ARS laboratory in 

Beltsville, MD. After 452 days of freezer storage, it was determined at Smithers-Viscient 

Laboratory that diflubenzuron was stable on peach, plum, and dried plum samples. Additional 

storage stability samples of each commodity were fortified with 0.5 ppm diflubenzuron, and 0.05 

ppm CPU and PCA at Smithers-Viscient Laboratory. 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 9 of 12

TABLE C.1 Summary of Recoveries of Diflubenzuron, CPU and PCA from Peach and Plum.

Matrix Type of 

Recovery1

Spike level 

(ppm) 

Sample size 

(n) Recoveries (%)2 Mean ± Std Dev 

(%) 

Diflubenzuron 

Peach 

(without pits) 

MV 0.05 7 75, 71, 92, 81, 106, 108, 104 91 ± 15 

0.5 7 86, 78, 88, 82, 98, 98, 97 90 ± 8 

CR 0.05 11 92, 93, 109, 78, 77, 95, 93, 90, 97, 

105, 94 93 ± 10 

0.5 8 112, 109, 78, 81, 84, 96, 105 95 ± 14 

SSCR 0.05 1 100 - 

0.5 2 94, 96 95 ± 1 

Plum 

(without pits) 

MV 0.05 6 83, 86, 88, 106, 111, 101 96 ± 12 

0.5 6 88, 85, 85, 91, 96, 95 90 ± 5 

CR 0.05 9 80, 72, 75, 114, 86, 93, 93, 100, 90 89 ± 13 

0.5 5 94, 72, 91, 87, 93 87 ± 9 

SSCR 0.05 2 90, 95 92 ± 4 

0.5 3 104, 100, 106 103 ± 3 

Dried Plum 

(without pits) 

MV 0.05 3 101, 101, 101 101 ± 0 

0.5 3 77, 85, 85 82 ± 5 

CR 0.05 2 102, 92 97 ± 7 

0.5 4 111, 71, 107, 99 97 ± 18 

SSCR 0.5 1 100 - 

CPU 

Peach 

(without pits) 

MV 0.005 3 94, 106, 104 101 ± 6 

0.05 3 95, 92, 92 93 ± 2 

CR 0.005 6 85, 84, 91, 107, 92, 96 92 ± 8 

0.05 3 95, 93, 114 101 ± 12 

SSCR 0.005 1 97 - 

0.05 1 109 - 

Plum 

(without pits) 

MV 0.005 3 94, 106, 104 101 ± 6 

0.05 3 95, 92, 92 93 ± 2 

CR 0.005 6 85, 84, 91, 107, 92, 96 92 ± 8 

0.05 3 95, 93, 114 101 ± 12 

SSCR 0.005 2 87, 93 - 

0.05 2 88, 92 90 ± 3 

Dried Plum 

(without pits) 

CR 0.005 1 96 - 

SSCR 0.05 1 105 - 

PCA 

Peach 

(without pits) MV 0.005 3 101, 109, 111 107 ± 5 

0.05 3 106, 103, 105 105 ± 2 

SSCR/CR 0.005 7 117, 93, 98, 112, 120, 119,129 113 ± 13 

0.05 3 114, 114 138 ± 42 

Plum 

(without pits) MV 0.005 3 117, 116, 116 116 ± 1 

0.05 3 98, 102, 101 100 ± 2 

SSCR/CR 0.005 5 116, 109, 116, 106, 116 113 ± 5 

0.05 1 110 - 

Dried Plum 

(without pits) SSCR/CR 0.005 1 98 - 

1

MV = Method validation; CR = Concurrent recovery; SSCR = Storage stability concurrent recovery 2

MV recoveries for diflubenzuron were from both laboratories

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 10 of 12

TABLE C.2. Summary of Storage Conditions. 

Matrix (RAC) Storage 

Temperature (°C) 

Storage Stability 

Recoveries (%) 

Actual Storage Duration 

(days) 

Interval of 

Demonstrated Storage 

Stability (days) 

Diflubenzuron 

Peach (without pits) <-20 

79.8 867 740 

96.2 867 740 

103 867 770 

Plum (without pits) <-20 

97.5 875 665 

98.5 875 665 

104 875 695 

Dried Plum (without pits) <-20 

61.2 800 740 

56.2 800 740 

45.5 800 770 

CPU 

Peach (without pits) <-20 

97.4 867 760 

111 867 760 

102 867 760 

95.9 867 770 

106 867 770 

110 867 770 

Plum (without pits) <-20 

94.4 875 760 

99.9 875 760 

92.9 875 760 

93.2 875 770 

98.8 875 770 

109 875 770 

Dried Plum (without pits) <-20 

55.9 800 685 

45.2 800 685 

48.9 800 685 

60.2 800 695 

50.8 800 695 

53.8 800 695 

PCA 

Peach (without pits) <-20 

58.2 903 767 

49.3 903 767 

54.8 903 767 

21.6 903 768 

19.0 903 768 

20.4 903 768 

Plum (without pits) <-20 

20.3 911 769 

28.8 911 769 

29.2 911 769 

48.4 911 770 

38.6 911 770 

38.9 911 770 

Dried Plum (without pits) <-20 

17.6 841 729 

16.0 841 729 

16.4 841 729 

22.0 841 730 

32.0 841 730 

21.7 841 730 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 11 of 12

`TABLE C.3. Residue Data from Crop Field Trials with Diflubenzuron.

Trial ID 

(City, State/Year) Zone Crop/ Variety Matrix Total Rate(lb ai/A) 

PHI 

(days)

Diflubenzuron

(ppm) 

CPU 

(ppm) 

PCA 

(ppm) 

Combined 

Residues1

(ppm) 

AR05 (Clarksville, AR/ 

2009) 4 Peach/ Crest 

Haven 

Fruit 

without pit 0.494 16 0.10, 0.09 <0.005 <0.005 0.11, 0.10 

CA39 

(Parlier, CA/2009) 10 Peach/ June 

Flame 

Fruit 

without pit 0.503 14 0.12, 0.09 <0.005 <0.005 0.13, 0.10 

CA41 

(Parlier, CA/2009) 

10 Peach/ June 

Flame 

Fruit 

without pit 0.508 

0 0.16, 0.29 <0.005 <0.005 0.17, 0.30 

7 0.15, 0.12 <0.005 <0.005 0.16, 0.13 

14 0.08, 0.08 <0.005 <0.005 0.09, 0.09 

21 0.08, <0.05 <0.005 <0.005 0.09, 0.06 

MI17 

(Fennville, MI/2009) 5 Peach/ 

Redskin 

Fruit 

without pit 0.502 14 0.40, 0.47 <0.005 <0.005 0.41, 0.48 

NC07 

(Jackson Springs/2009) 2 Peach/ 

Contender 

Fruit 

without pit 0.504 16 0.13, 0.14 <0.005 <0.005 0.14, 0.15 

NJ04 

(Cream Ridge, NJ/2009) 2 Peach/ 

Loring 

Fruit 

without pit 0.510 15 0.09, 0.17 <0.005 <0.005 0.10, 0.18 

NJ05 

(Cream Ridge, NJ/2009) 2 Peach/ 

Suncrest 

Fruit 

without pit 0.499 14 0.26, 0.26 <0.005 <0.005 0.27, 0.27 

CA38 

(Gridley, CA/2009) 10 Plum/ 

French 

Fruit 

without pit 0.484 13 0.06, 0.09 <0.005 <0.005 0.070, 0.10 

CA40 

(Parlier, CA/2009) 10 Plum/ 

John W 

Fruit 

without pit 0.502 14 <0.05, <0.05 <0.005 <0.005 0.060, 0.060

CA42 

(Parlier, CA/2009) 10 Plum/Black 

Splendor 

Fruit 

without pit 0.505 14 <0.05, <0.05 <0.005 <0.005 0.060, 0.060

CA43 

(Gridley, CA/2009) 10 Plum/ French 

Fruit 

without pit 0.484 13 

0.11, 0.10 <0.005 <0.005 0.12, 0.11 

Dried Fruit 

without pit 0.19 <0.005 <0.005 0.20 

WA18 

(Wapato, WA/ 2009) 11 Plum/ 

Late 

Fruit 

without pit 0.499 10 0.05, 0.06 <0.005 <0.005 0.060, 0.070

1

Diflubenzuron, CPU and CPA residues were determined by Smithers Viscient Laboratory. For residues <0.05 and <0.005 ppm, values of 0.05 

and 0.005 were used to determined combined residues of diflubenzuron + CPU + PCA 

TABLE C.4. Summary of Residue Data from Crop Field Trials with Diflubenzuron.

Commodity 

Total Applic. 

Rate 

(lb ai/A) 

PHI 

(days) 

Combined Residues (diflubenzuron, CPU and PCA) 

(ppm) 

n Min. Max. HAFT1 Median Mean Std. Dev.

Peach 

0.50 

0 2 0.17 0.30 0.24 0.24 0.24 0.090 

7 2 0.13 0.16 0.14 0.14 0.14 0.020 

14-16 14 0.090 0.48 0.44 0.14 0.19 0.12 

21 2 0.060 0.090 0.080 0.080 0.080 0.020 

Plum 13-14 10 0.060 0.12 0.12 0.060 0.080 0.020 

Dried Plum 13 1 0.20 0.20 NA2 NA NA NA 1

HAFT = Highest Average Field Trial. 

2

NA = Not applicable

D. CONCLUSION 

The magnitude of the residue study of diflubenzuron on peach and plum was conducted 

consistent with standard agricultural practices according to proposed experimental designs. The 

weather conditions at each site were within normal parameters during the growing season, except 

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Crop Field Trial/ Residue Decline – Peach and Plum 

PMRA Submission No. /DP Barcode D423328 /MRID No. 49399504 Page 12 of 12

that anomalous weather events were recorded at the NJ04 and NJ05 field sites where temperature 

and rainfall varied. These occurrences had no adverse impact on the study. 

The LC/MS/MS residue analytical methods used for determining diflubenzuron, CPU, and PCA 

in/on peach and plum were validated and adequate for data collection. Storage stability data 

indicated that residues were stable under the conditions that samples were held between harvest 

and analysis. Following two foliar applications of Dimilin 2L at 14 days RTI, combined residues 

of diflubenzuron, CPU and PCA were 0.06-0.48 ppm in peaches harvested at 14-16 days PHI 

and 0.06-0.12 ppm in plums harvested at 10-14 days PHI. Combined residues of diflubenzuron, 

CPU and PCA in dried plum were 0.20 ppm. In the decline trial, combined residues on peach 

declined from 0.24 ppm at 0-day PHI to 0.08 ppm at 21-days PHI. 

E. REFERENCES

US EPA DER (14-Sep-2006): MRID 46609501. Corley, J. (2005) Diflubenzuron: Magnitude of 

the Residue on Small Grain. Lab Project Number: 08024.02-PTR01. Unpublished study 

prepared by Interregional Research Project No. 4 (IR-4). 800 p. 

F. DOCUMENT TRACKING

RDI: T. Morton (6/20/2015) 

Petition Number(s): 4E8306 

DP Barcode(s): D423328 

PC Code: 108201 

Template Version June 2005.

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