Document ID: EPA-HQ-OPP-2006-0181-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-11-29T05:00Z

SEQ CHAPTER \h \r 1 Primary Evaluator

Date:  14-SEP-2006

	George F. Kramer, Ph.D., Senior Chemist

Registration Action Branch (RAB1)

Health Effects Division (HED) (7509C)

	Approved by

Date:  14-SEP-2006

	P.V. Shah, Ph.D. Branch Senior Scientist

RAB1/HED (7509C)

	

  SEQ CHAPTER \h \r 1 This DER was originally prepared under contract by
Dynamac Corporation (1910 Sedwick Rd., Building 100, Durham, NC 27713;
submitted 06/23/2006).  The DER has been reviewed by HED and revised to
reflect current Office of Pesticide Programs (OPP) policies.

STUDY REPORT:

46609401.  Samoil, K. (2005) Diflubenzuron:  Magnitude of the Residue on
Peanut.  Lab Project Number:  07737.01-TXP02.  Unpublished study
prepared by Interregional Research Project No. 4 (IR-4).  645 p.  

EXECUTIVE SUMMARY:

Twelve peanut field trials were conducted in EPA Zones 2, 3, and 6
during the 2001 growing season.  At each trial location, diflubenzuron
(2 lb/gal flowable concentrate (FlC)) was applied three times as
broadcast foliar applications using ground equipment at 0.121-0.132 lb
ai/A/application for a total rate of 0.373-0.385 lb ai/A.  The first
application was at first bloom, the second was 14 (± 1) days after the
first, and the third was 28 (± 1) days before harvest at nine sites, 20
days at two sites and 26 days at one site.  A single control and single
or duplicate treated samples of peanuts and peanut hay were harvested
from each site at 20-28 days after treatment (DAT).   SEQ CHAPTER \h \r
1  Additional samples of peanut nutmeat and hay were collected from one
site at 15, 20, 29, and 35 DAT to generate residue decline data.  All
samples were stored frozen for up to 481 days prior to residue
extraction and analysis, an interval partially supported by available
storage stability data.

The harvested samples were analyzed for residues of diflubenzuron using
a high-performance liquid chromatography (HPLC)/ultraviolet (UV) method
for nutmeat and hay, for residues of 4-chlorophenylurea (CPU) using
HPLC/mass spectrometry (MS)/MS or UV for nutmeat or gas chromatography
(GC)/MS methods for hay, and for residues of 4-chloroaniline (PCA) using
GC/MS method for nutmeat and hay.  These methods, which are similar or
based on method submissions previously deemed acceptable by the Agency,
were adequately validated in conjunction with the field sample analyses.

The results from three field sites (Trial IDs TN03, GA01, and GA03)
showed possible sample contamination since residues of diflubenzuron or
CPU in/on control samples of peanut nutmeat were equal to or higher than
treated samples.  No adequate explanation was provided except a
statement from the petitioner commenting that the magnitude of residues
in/on control samples which bore quantifiable residues was low relative
to the residues in/on treated samples.

When samples from Trial IDs TN03, GA01, and GA03 are excluded, the
combined residues of diflubenzuron, CPU and PCA ranged <0.060-<0.070 ppm
in/on 18 samples of peanut nutmeat and 1.12-18.46 ppm in/on 11 samples
of peanut hay that were harvested 20-28 days following the last of three
foliar treatments of a 2 lb/gal FlC test formulation for a total
application rate of 0.373-0.385 lb ai/A.  The HAFT values were <0.070
ppm for nutmeat and 18.46 ppm for hay.  The average combined residues
were 0.06 ppm for nutmeat and 7.14 ppm for hay.

The submitted residue decline data for peanut nutmeat is inconclusive,
and a trend could not be established because residues of the parent and
its metabolites were all below the respective LOQs from samples
collected at PHIs of 15, 20, 29, and 35 days.  Although detectable
residues in peanut hay were observed from the decline trial, a
meaningful trend in residue decline could not also be established since
residue levels fluctuated at various sampling intervals.

STUDY/WAIVER ACCEPTABILITY/DEFICIENCIES/CLARIFICATIONS:

Under the conditions and parameters used in the study, the peanut field
trial residue data are classified as partially acceptable to satisfy the
guideline requirement for crop field trials (Residue Chemistry Guideline
OPPTS 860.1500).  The data from three GA trials are unacceptable because
the reported diflubenzuron or CPU residues in/on control samples which
were higher than those of treated samples.  The acceptability of this
study for regulatory purposes is addressed in the forthcoming U.S. EPA
Residue Chemistry Summary Document DP# 321623.

COMPLIANCE:

Signed and dated Good Laboratory Practice (GLP), Quality Assurance and
Data Confidentiality statements were provided.  No deviations were
reported that would substantially impact the validity of the study.

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.  



TABLE A.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 Product (EP)	2 lb/gal FlC formulation; DIMILIN® 2L (EPA Reg.
No. 400-461)

Regulated Metabolite	

Common name	4-chlorophenylurea (CPU)

Regulated Metabolite	

Common Name	4-chloroaniline (PCA)

TABLE A.2.	Physicochemical Properties of Diflubenzuron.

Parameter	Value	Reference

Melting range	230-232 °C	  HYPERLINK
"http://www.arsusda.gov/acsl/services/ppdb/textfiles/DIFLUBENZURON" 
http://www.arsusda.gov/acsl/services/ppdb/textfiles/DIFLUBENZURON 

pH	Not available

	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

	B.	EXPERIMENTAL DESIGN

B.1.	Study Site Information

Peanuts were grown and maintained at each trial site (Table B.1.1) using
typical agricultural practices for the respective geographical region. 
Information pertaining to soil conditions, temperature, and
precipitation was provided.  Irrigation for all sites and weather
conditions were within normal variations for the region.  Information
was also provided on the maintenance chemicals and other pesticides used
at each site.

TABLE B.1.1.	Trial Site Conditions.

Trial Identification

(City, State; Year)	Soil Characteristics1

	Type	%OM	pH	CEC (meq/g)

Salisbury, MD; 2001	Loamy Sand	0.8	6.0	NR

Crossville, TN; 2001	Sandy Loam	2.5	5.8	NR

Crossville; TN2001	Sandy Loam	2.5	5.8	NR

Rocky Mt, NC; 2001	Sandy Loam	1.2	6.0	NR

Weslaco, TX; 2001	Sandy Loam	0.5	8.1	NR

Weslaco, TX; 2001	Sandy Loam	0.5	8.1	NR

Tifton, GA; 2001	Sand	0.67	6.2	NR

Tifton, GA; 2001	Sand	0.67	6.2	NR

Tifton, GA; 2001	Sand	0.67	6.2	NR

Colony, OK; 2001	Sand	0.4	7.1	NR

Salisbury, MD; 2001	Sandy Loam	1.1	6.2	NR

Citra, FL; 2001	Sand	0.8	4.9-5.5	NR

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.

NR = Not Reported

TABLE B.1.2.  Study Use Pattern on Peanuts.

Location

City, State; Year; 

Trial ID	

EP1	Application	

Tank Mix/ Adjuvants

Method; Timing	Volume GPA	Single Rate

(lb ai/A)	RTI2

(days)	Total Rate

(lb ai/A)

	Salisbury, MD 2001; MD01	2 lb/gal FlC	Three broadcast foliar
applications; first bloom, full bloom, some peanuts mature	40-41
0.125-0.126	13, 14	0.376	None

Crossville, TN 2001; TN03	2 lb/gal FlC	Three broadcast foliar
applications; vegetative	23-24	0.122-0.127	14, 28	0.374	None

Crossville, TN2001;

TN04	2 lb/gal FlC	Three broadcast foliar applications; vegetative	23-24
0.125-0.126	14, 28	0.376	None

Rocky Mt, NC 2001;NC01	2 lb/gal FlC	Three broadcast foliar applications;
bloom, late bloom, pod-fill	18-19	0.123-0.128	14, 32	0.377	None

Weslaco, TX 2001; TX04	2 lb/gal FlC	Three broadcast foliar applications;
first flower, flowering, nuts from first flowers pink	14-17	0.121-0.132
13, 35	0.379	None

Weslaco, TX 2001; TX05	2 lb/gal FlC	Three broadcast foliar applications;
first flower, flowering, nuts from first flowers pink	14-18	0.123-0.126
14, 30	0.374	None

Tifton, GA 2001; GA01	2 lb/gal FlC	Three broadcast foliar applications;
first bloom, bloom, immature peanuts	20	0.125-0.127	15, 12	0.378	None

Tifton, GA 2001; GA02	2 lb/gal FlC	Three broadcast foliar applications;
first bloom, bloom, immature peanuts	20	0.124-0.125	15, 18	0.374	None

Tifton, GA 2001;

GA03	2 lb/gal FlC	Three broadcast foliar applications; first bloom,
bloom, immature peanuts	20	0.124-0.126	15, 18	0.375	None

Colony, OK 2001;

OK01	2 lb/gal FlC	Three broadcast foliar applications; bloom, pegging,
beginning maturity	11	0.123-0.126	13, 34	0.373	None

Salisbury, MD 2001; MD17	2 lb/gal FlC	Three broadcast foliar
applications; first bloom, beginning to form pegs, beginning to form red
skins	41-68	0.124-0.127	14, 19	0.377	None

Citra, FL 2001;

FL52	2 lb/gal FlC	Three broadcast foliar applications; first bloom,
vegetative bloom, fruiting	15-16	0.126-0.132	13, 22	0.385	None

1  EP = End-use Product; DIMILIN® 2L.

2  RTI = Retreatment Interval.

TABLE B.1.3.	Trial Numbers and Geographical Locations.

NAFTA Growing Zones	Peanuts

	Submitted	Requested

Canada	U.S.

2	8	---	8

3	1	---	1

6	31	---	2

8	---	---	1

Total	12	NA	12

1  One trial was very near Zone 8 and will suffice to fulfill the
geographic representation.

B.2.	Sample Handling and Preparation

Single control and treated samples of peanut hay and duplicate treated
samples of peanuts (amount not reported) were harvested from each trial
site at commercial maturity 20-28 days after the third application of
the test formulation.  Peanut plants were pulled or dug from the ground
(by hand or using a mechanical digger).  Hay was allowed to dry in the
field before harvest to achieve a moisture content of 10-12%.  Dried
peanuts were shelled by hand or mechanical sheller.  All samples were
placed in frozen storage within 4.0 hours of collection.  Field storage
time was not documented.  Samples were shipped frozen by ACDS freezer
truck to the analytical laboratory (PTRL West, Hercules, CA) where
samples were stored at <0 °C until extraction for analysis.

B.3.	Analytical Methodology

Samples were analyzed for diflubenzuron, CPU, and PCA using separate
methods based on those described in “Dimilin 25W, Dimilin 80WD, and
Dimilin 2L in Almonds:  Magnitude of the Residue Study,” Janine E.
Rose, PTRL Study No, 723W, September 1999.  Due to analytical
difficulties, CPU analysis for hay were done based on the method
described in “Gas Chromatographic Determination of Diflubenzuron
Metabolite A:  Parachlorophenyl Urea in Mushrooms,” D. Uhden, S.E.
Kane, and M.A Morgenstern, Colorado Analytical Study No. 1248, November
20, 1995.

Samples of peanut nutmeat and hay were analyzed for diflubenzuron using
an HPLC/UV method.  Briefly, residues are extracted twice with ethyl
acetate and then filtered.  Residues are evaporated to dryness and
redissolved in hexane.  Residues are partitioned with acetonitrile (ACN)
and again evaporated to dryness.  Residues are redissolved with
dichloromethane, and cleaned up on a Florisil solid-phase extraction
(SPE) column.  After clean up, residues are analyzed by HPLC on a C18
column with UV detection.  The limit of quantitation (LOQ) is 0.05 ppm
from nutmeat and 0.1 ppm from hay, the calculated limit of detection
(LOD) is 0.026 ppm for nutmeat and was not calculated for hay.

Samples of peanut nutmeat were analyzed for CPU using HPLC/MS/MS or
HPLC/UV method.  Briefly, samples are extracted twice with ACN and
centrifuged.  The supernatants are combined and partitioned with hexane.
 The ACN layer is concentrated to dryness, redissolved in ACN and water,
and sequentially cleaned up on a C18 SPE column and silica-gel SPE
column.  After clean up, residues are analyzed by HPLC/MS/MS or HPLC/UV.
 The LOQ is 0.005 ppm for nutmeat, the LOD was not calculated.

Samples of peanut hay were analyzed for CPU using a GC/MS method. 
Briefly, samples are dried with sodium sulfate and extracted with ethyl
acetate.  Residues are evaporated to dryness, redissolved in acetone and
petroleum ether, and cleaned up on a silica-gel SPE column.  Again,
residues are evaporated to dryness and redissolved in ACN.  The sample
is filtered and derivatized in a glass tube with heptafluorobutyric
anhydride for 10 minutes.  Residues are then analyzed by GC/MS.  The LOQ
is 0.01 ppm for hay, the LOD was not calculated.

Samples of peanut nutmeat and hay were analyzed for PCA using a GC/MS
method.  Briefly, residues are acidified with HCl and sonicated for 30
minutes at 60 °C.  NaOH and NaCl are added, and residues are extracted
three times with hexane.  Residues are then partitioned with 0.1 N HCl,
neutralized and extracted with hexane.  Extracts are dried and cleaned
up with a Florisil column, derivatized with heptafluorobutyric acid for
10 minutes, after which water, sodium carbonate and hexane are added. 
Residues in the hexane layer are analyzed by GC/MS.  The LOQ is 0.005
ppm for nutmeat and hay and the calculated LOD is 0.001 ppm.

In conjunction with the analysis of field trial samples, the above
methods were validated using control samples of peanut nutmeat and hay
fortified with diflubenzuron, CPU or PCA at 0.005-20 ppm.

C.	RESULTS AND DISCUSSION

In 12 peanut field trials conducted during 2001, diflubenzuron (2 lb/gal
FlC) was applied three times to fields as broadcast foliar applications
using ground equipment at 0.121-0.132 lb ai/A/application during crop
development.  A single control and single or duplicate treated samples
of mature peanut and peanut hay were harvested from each site at 20-28
DAT.  At one site, samples were also collected at 15, 20, 29, and 35 DAT
to assess residue decline.

The HPLC/UV (for nutmeat and hay), HPLC/MS/MS or UV (for nutmeat) or
GC/MS (for hay), and GC/MS (for nutmeat and hay) methods used to
determine residues of diflubenzuron, CPU, and PCA in/on peanut nutmeat
and hay were adequately validated in conjunction with the field sample
analyses.  Method recoveries from concurrent analysis of samples as well
as from additional method verification (see Table C.1) are well within
the acceptable range of 70-120% except for two samples of nutmeat which
reported CPU recoveries of 64% and 68% and one sample of peanut hay
which reported CPU recoveries of 50%.  In addition, method validation
recoveries of diflubenzuron from hay at the 0.05 ppm fortification level
reported only 9 ± 1% average recovery; however, residue values of
diflubenzuron in hay were well above this level from field samples. 
Adequate examples calculation and samples chromatograms were provided.

Samples of peanut nutmeat and hay samples were stored frozen for up to
481 days prior to residue extraction and analysis (Table C.2.1).  To
validate sample storage conditions and intervals, a freezer storage
stability study was conducted as part of the residue field study.  The
results of this study (Table C.2.2) indicate that diflubenzuron (average
corrected stored recovery of 93%) is relatively stable in/on nutmeat for
up to 295 days; however, CPU (average corrected stored recovery of 67%)
and PCA (average corrected stored recovery of 63%) exhibited 33-37%
reduction in residues after 421 and 289 days of frozen storage,
respectively.  A similar storage stability profile was observed for
peanut hay.  Diflubenzuron (average corrected stored recovery of 82%) is
relatively stable in/on hay for up to 356 days; CPU (average corrected
stored recovery of 29%) and PCA (average corrected stored recovery of
75%) exhibited 25-71% reduction in residues after 484 and 338 days of
frozen storage, respectively.  

The results suggest that residues of CPU and PCA should be corrected in
order to determine the residue levels that were present at the time of
sample collection.  However, HED has determined that correction of CPU
and PCA residues for degradation during storage would not have a
significant effect on the results of the submitted field trials because
individual residues of CPU and PCA in/on treated samples were mostly
below the LOQ (<0.005 ppm).  These data are adequate to support the
storage conditions and intervals of the field trial samples.

Following application of diflubenzuron totaling 0.373-0.385 lb ai/A, the
combined residues of diflubenzuron, CPU and PCA were <0.060-<0.070 ppm
in/on 18 samples of peanut nutmeat harvested 20-28 DAT.  Combined
residues were 1.12-18.46 ppm in/on 11 treated samples of peanut hay
(Table C.3.).  HAFT values were <0.070 ppm for nutmeat and 18.46 ppm for
hay; average combined residues were 0.06 ppm for nutmeat and 7.14 ppm
for hay (Table C.4).  In three different trials, residues of
diflubenzuron or CPU in peanut nutmeat were equal to or higher in
control samples than treated samples; these residues were not included
in the calculations from Table C.4.

The submitted residue decline data for peanut nutmeat is inconclusive,
and a trend could not be established because residues of the parent and
its metabolites were all below the respective LOQs at PHIs of 15, 20,
29, and 35 days.  Although detectable residues in peanut hay were
observed from the decline trial, a meaningful trend with regard to
residue decline could not also be established since residue levels
fluctuated at various sampling intervals.

Common cultural practices were used to maintain the test crop.  The
weather conditions did not have a notable impact on the residue data. 
It is unclear whether or not the maintenance chemicals played a role in
the high levels of CPU residues found in the TN03 and GA01 trials sites,
as CPU is a metabolite of the maintenance chemical PCNB, and may have
contributed to high residue levels in control samples.  Other trial
sites which also used this maintenance chemical did not experience high
residues of CPU in control samples.

TABLE C.1.	Summary of Concurrent and Method Recoveries of Diflubenzuron
from Peanuts.

Analyte	

Matrix	Spike level

 (ppm)	Sample size

(n)	

Recoveries (%)	Mean std dev

(%)

Concurrent

Diflubenzuron	Nutmeat	0.05	4	74, 76, 80, 86	79 ± 5

0.1	7	80, 86, 90, 94, 95, 97, 102	92 ± 7

0.2	2	761, 921	84

CPU

0.01	14	64, 68, 70, 80, 80, 90, 90, 100, 100, 100, 110, 110, 120, 120	93
± 19

PCA

0.005	14	95, 97, 98, 98, 101, 102, 102, 105, 106, 106, 107, 108, 108,
110	103 ± 5

Diflubenzuron	Hay	0.1	4	701, 841, 881, 1021	86 ± 13

0.5	5	721, 72, 76, 79, 811	76 ± 4

CPU

0.02	6	76, 78, 801, 801, 102, 109	88 ± 14

0.10	1	99	99

PCA

0.005	2	110, 118	114

0.020	6	90, 93, 94, 97, 98, 101	96 ± 4

Method validation

Diflubenzuron	Nutmeat	0.05	3	102, 106, 116	108 ± 7

0.5	3	84, 85, 85	85 ± 1

1.0	3	81, 97, 98	92 ± 10

CPU

0.005	3	80, 100, 100	93 ± 12

0.05	3	96, 98, 100	98 ± 2

0.1	3	91, 92, 93	92 ± 1

PCA

0.005	3	100, 104, 120	108 ± 11

0.05	3	111, 112, 113	112 ± 1

0.10	3	110, 112, 115	112 ± 3

Diflubenzuron	Hay	0.05	3	8, 10, 10	9 ± 1

0.5	3	88, 89, 91	89 ± 2

1.0	3	98, 103, 104	102 ± 3

202	3	85, 87, 92	88 ± 4

CPU

0.01	3	501, 1001, 1101	87 ± 32

0.1	3	931, 931, 1001	95 ± 4

PCA

0.005	3	106, 108, 110	108 ± 2

0.05	3	100, 112, 115, 	109 ± 8

0.10	3	96, 103, 118	106 ± 11

1  Reported recoveries were corrected by the petitioner for apparent
residue in control samples.

2  Recoveries of samples fortified with diflubenzuron at 20 ppm were
only reported in the summary table of the submission.

TABLE C.2.1	Summary of Storage Conditions.

Analyte 	Storage Temperature (°C)	

Matrix	Actual Storage Duration1 

(days)	Interval of Demonstrated Storage Stability (days)

Diflubenzuron	<0	Nutmeat	244	295

Hay	349	356

CPU

Nutmeat	408	421

Hay	481	484

PCA

Nutmeat	266	289

Hay	323	338

1  From harvest to extraction for analysis.  Extracts were stored for up
to 9 days before analysis

TABLE C.2.2	Stability of Diflubenzuron and its Metabolites in Frozen
Peanut Matrices.

Matrix	

Analyte	

Spike Level

(ppm)	

Storage interval (days)	Freshly Fortified Recovery (%)	

Stored Sample Residues (%)	Average Corrected Stored Recovery (%)

Nutmeat	Diflubenzuron	0.5	295	75, 69

[72]	65, 68

[67]	93

	CPU	0.5	421	79, 84

[81]	54, 53

[54]	67

	PCA	0.1	289	70, 71

[71]	41, 39

[45]	63

Hay	Diflubenzuron	0.5	356	95, 103

[99]	83, 79

[81]	82

	CPU	0.5	484	88, 108

[98]	21, 35

[28]	29

	PCA	0.1	338	102, 99

[101]	77, 76

[76]	75

TABLE C.3.	Residue Data from Peanut Field Trials with Diflubenzuron.

Trial ID

(City, State; Year)	

Zone	

Crop

Variety	Total Rate (lb ai/A)	

Matrix	

PHI (days)	

Residues (ppm)1

Diflubenzuron	

CPU	

PCA	

Combined

Salisbury, MD 2001

MD01	2	VA-C98R	0.376	Nut	28	<0.05, <0.05	<0.005, 0.005	<0.005, <0.005
<0.060, <0.060

Hay

No sample	No sample	No sample	No sample

Crossville, TN 2001

TN03	2	VA 98R	0.374	Nut	28	<0.05, <0.05	0.0112, 0.0192	<0.005, <0.005
<0.0662, <0.0742

Hay

18.39	0.052	0.016	18.46

Crossville, TN 2001

TN04	2	VA-C92R	0.376	Nut	28	0.059, 0.060	<0.005, <0.005	<0.005, <0.005
<0.069, <0.070

Hay

10.69	0.065	0.037	10.79

Rocky Mt, NC 2001

NC01	2	VA 98R	0.377	Nut	28	<0.05, 0.055	<0.005, <0.005	<0.005, <0.005
<0.060, <0.065

Hay

17.00	0.018	0.018	17.04

Weslaco, TX 2001

TX04	6	Florunner	0.379	Nut	15	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005
<0.060, <0.060

	20	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005	<0.060, <0.060

	29	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005	<0.060, <0.060

	35	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005	<0.060, <0.060

Hay	15	11.03	0.029	0.017	11.08

	20	9.61	0.012	0.021	9.64

	29	8.39	<0.01	0.015	<8.42

	35	10.31	0.017	0.021	10.35

Weslaco, TX 2001

TX05	6	Florunner	0.374	Nut	28	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005
<0.060, <0.060

Hay

7.86	0.019	0.021	7.90

Tifton, GA 2001

GA01	2	NCV11	0.378	Nut	26	<0.05, <0.05	<0.0052, <0.0052	<0.005, <0.005
<0.0602, <0.0602

Hay

2.64	0.012	0.047	2.70

Tifton, GA 2001

GA02	2	C99R	0.374	Nut	20	0.052, 0.060	<0.005, <0.005	<0.005, <0.005
<0.062, <0.070

Hay

1.05	0.013	0.054	1.12

Tifton, GA 2001

GA03	2	Georgia Green	0.375	Nut	20	0.0722, 0.0972	<0.005, <0.005	<0.005,
<0.005	<0.0822, <0.1072

Hay

1.11	0.024	0.046	1.18

Colony, OK 2001

OK01	6	Tamspan	0.373	Nut	27	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005
<0.060, <0.060

Hay

1.64	0.019	0.013	1.67

Salisbury, MD 2001

MD17	2	VA-C98R	0.377	Nut	28	<0.05, <0.05	<0.005, <0.005	<0.005, <0.005
<0.060, <0.060

Hay

7.11	0.046	0.017	7.17

Citra, FL 2001

FL 52	3	Florunner	0.385	Nut	28	<0.05, <0.05	<0.005, 0.006	<0.005, <0.005
<0.060, <0.060

Hay

1.89	0.025	0.137	2.05

1  The LOQ is 0.05 ppm for residues of diflubenzuron, and 0.005 ppm for
residues of CPU and PCA in nutmeat.  The LOQ is 0.05 ppm for residues of
diflubenzuron, 0.01 ppm for residues of CPU, and 0.005 ppm for residues
of  PCA in hay.

2   Residues found in control samples were greater than that of treated
samples; these values were excluded from calculations in Table C.4. 
Control samples from GA03 bore residues of diflubenzuron at 0.097 ppm
and 0.084 ppm; control samples from TN03 bore residues of CPU at 0.022
ppm and 0.026 ppm; control samples from GA01 bore residues of CPU at
0.015 ppm and 0.006 ppm.

TABLE C.4.	Summary of Combined Residue Data from Peanut Field Trials
with Diflubenzuron.

Commodity	Total Applic. Rate (lb ai/A)	PHI (days)	Residue Levels (ppm)1

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

Nutmeat	0.373-0.385	20-28	18	<0.060	<0.070	<0.070	0.060	0.060	0.0

Hay

	11	1.12	18.46	18.46	7.17	7.14	6.24

1   The LOQ is 0.05 ppm for residues of diflubenzuron, and 0.005 ppm for
residues of CPU and PCA in nutmeat.

2   HAFT = Highest-Average Field Trial. 

D.	CONCLUSION

The peanut field trial data are partially acceptable to support the use
of diflubenzuron on peanuts for up to three foliar treatments at a total
seasonal rate of 0.375 lb ai/A, a PHI of 20-28 days, and a retreatment
interval of 12-35 days.  The data from three field sites (Trial IDs
TN03, GA01, and GA03) are unacceptable because the reported
diflubenzuron or CPU residues in/on control samples which were higher
than those of treated samples.  The combined residues of diflubenzuron,
CPU and PCA ranged <0.060-<0.070 ppm in/on 18 samples of peanut nutmeat
and 1.12-18.46 ppm in/on 11 samples of peanut hay that were harvested
20-28 days following the last of three foliar treatments of a 2 lb/gal
FlC test formulation for a total application rate of 0.373-0.385 lb
ai/A.  The HAFT values were <0.070 ppm for nutmeat and 18.46 ppm for
hay.  The average combined residues were 0.06 ppm for nutmeat and 7.14
ppm for hay.

E.	REFERENCES

None

F.	DOCUMENT TRACKING

RDI:  RAB1 Chemists (8/23/06)

Petition Number(s):  PP#5E6967

DP#:  321623

PC Code:  108201

Template Version June 2005

	Diflubenzuron/PC Code 108201/IR-4

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