**UNITED STA TES ENVIRONMENTA**  **L PROTECTION A GENCY** 

**MEMORANDUM Date:**  **27 -**  **OCT -**  **20 1**  **1 SUBJECT:**  **Difenoconazole .** 

**Add Seed Treatment**  **Oat Commodities, Rye Commodities, and Wheat Hay Analytical Chemistry and Residue Data.**  **PC Code:** 128847 **Decision No s**  **.:** 440121 **Petition No s**  **. :**  0F 7785 **Risk A**  **ss essment Type**  **:** N ot Applicable **T XR No.:**  N ot Applicable **MRID No .**  **:** None **FROM:** Bonnie Cropp - Kohlligian, Environmental Scientist

Risk Assessment Branch 4 Health Effects Division (7509P) **THROUGH:** Susan V. Hummel, Chemist/Senior Scientist

Risk Assessment Branch Health Effects Division (7509P) **TO:** Rosemary

Kearns Fungicide Branch Registration Division (7505P) Difenoconazole is a broad spectrum fungicide belonging to the triazole group of (Group 3) that acts by

inhibiting sterol demethyl ation use as a seed treatment on barley currentl y registered in the U.S. for foliar appl Page 1 of 23 **UNITED STA**

**TES ENVIRONMENTA L PROTECTION A** **GENCY WA** **SHINGTON, D.C. 20460 OFFICE OF**  **CHEMICAL SAFETY AND**  **POLLUTION PREVENTION**

**. Amended**  **Section 3 Registration (Dividend ®**  **Seed Treatment Uses on Oats and Rye**  **and Establish Tolerances in/on Oat Commodities, Rye Commodities, and Wheat Hay**  **. Summary of**  **Analytical Chemistry and Residue Data. DP Barcode**  **s :**  384073 **Registration No .**  **:** 100 - 740 **Regulatory Action :**  Amended Section 3 Registration ot Applicable **Case No.:** 7014

**CAS No.:** 1 19446 - 68 - 3 **40 CFR:** 180.475 Kohlligian, Environmental Scientist Risk Assessment Branch 4 Health Effects Division (7509P) Susan V. Hummel, Chemist/Senior Scientist Risk Assessment Branch 4 Health Effects Division (7509P) Rosemary

Kearns /Tony

Kish ( RM 22) Fungicide Branch Registration Division (7505P) Difenoconazole is a broad spectrum fungicide belonging to the triazole group of

that acts by

inhibiting sterol demethyl ation . It is currently registered in the U.S. for barley , canola , cotton , sweet corn, wheat, and triticale. I t is also for foliar appl ications on numerous crops , but not cereal grains **UNITED STA**

**TES ENVIRONMENTA L PROTECTION A** **GENCY CHEMICAL SAFETY**  **POLLUTION PREVENTION**

**® Fungicide) to**  **and Establish Tolerances in/on**

**Summary of** Section 3 Registration

Difenoconazole is a broad spectrum fungicide belonging to the triazole group of fungicides . It is currently

registered in the U.S. for , sweet corn, wheat, and triticale. I t is also , but not cereal grains .Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 2 of 23 Tolerances for difenoconazole in/on plant commodities are currentl y established under §180.475(a)(1) and are expressed in terms of difenoconazole per se . Tolerances are established for numerous raw agricultural and processed commodities rang ing from 0.01 ppm to 35 ppm; including tolerances for barley grain (0.1 ppm), barley

hay (0.05 ppm), barley

straw (0.05 ppm), wheat grain (0.1 ppm), wheat forage (0.1 ppm), and wheat straw (0.1 ppm) . Import tolerance s are also established for a number of raw agricultural commodities (RACs), including rye grain (0.1 ppm). [Note: Inaccordance with 40 CFR 180.1(g), tolerances established in/on wheat RACs ap ply

to triticale RACs.] Tolerances for difenoconazole on livestock commodities are currentl y established under §180.475(a)(2) and are expressed in terms of difenoconazole and its metabolite, CGA - 205375 [ 1 - [2 - chloro - 4 - (4 - chloro - phenox y)phen yl ] - 2 - [1,2,4]triazol - 1 - yl - ethanol ] . T olerances are established for tissue, milk, and egg rang ing from 0.01 ppm to 0.20 ppm. Under PP# 0F7785, Amended Section F submitted to T. Kish ( via email from R. Rezaaiyan dated 4/2 7/11) , Sy

ngenta Crop Protection, Inc. (hereafter referred to as S yn genta) is proposing the establishment of tolerances for residues of difenoconazole [1 - [2 - [2 - chloro - 4 - (4 - chlorophenox y)phen yl ] - 4 - methyl - 1,3 - dioxolan - 2 - ylmethyl] - 1H - 1,2,4 - triazole] in/on the following raw agricultural commodities:

Oat s , grain ................................ ................................ ............ 0.1 ppm Oat s , forage ................................ ................................ .......... 0.1 ppm Oat s , hay ................................ ................................ .............. 0.1 ppm Oat s , straw ................................ ................................ ............ 0.1 ppm Rye, grain 1

................................ ................................ ............ 0.1 ppm Rye, forage ................................ ................................ ........... 0.1 ppm Rye, straw ................................ ................................ ............ 0.1 ppm Wheat , hay ................................ ................................ ........... 0.1 ppm 1 Note that a lthough difenoconazole is not currently registered in the U.S. for use on rye, an import tolerance is currently established under 40 CFR §180.475 (a)(1) for residues of difenoconazole in/on rye grain at 0.1 ppm. In conjunction with PP#0F7785, Sy ngenta is requesting an amended Section 3 registr ation for a 3.1 lb/gal flowable concentrate for seed treatment (FS) formulation (Dividend® Fungicide; EPA Reg. No. 100 - 740) to add seed treatment uses on oats and ry e at a maximum use rate of 11 g ai/100 lb seed; the same use currently registered in the U. S. on other cereal grain seed, including barley , wheat, and triticale. There is a proposed restriction for the grazing of green oat and rye forage s until 55 day s after planting on the submitted proposed label but not on Section B of the petition; this sam e restriction is currently registered for the grazing of green wheat and triticale forage s . No new residue chemistry data were submitted with the current petition. Instead the petitioner has requested the translation of available wheat and barley magni tude of the residue data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses ofDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 3 of 23 d ifenoconazole on oats and rye. These data have been re - evaluated herein primarily for the purposes of harmonization and secondarily f or the purposes of setting tolerances in accordance with current guidance . [Note: S ince no new residue chemistry data were submitted, o nly the subject wheat and barley field trial data have been discussed in depth under Detailed Consideration. ] Because difenoconazole is a triazole compound, HED requires that samples from any metabolism, field trial, and/or processing study be anal yz ed for the triazole metabolites triazolylalanine (TA), triazolyl acetic acid (TAA), and 1,2,4 - triazole (1,2,4 - T). H ED issued guidance on the residue chemistry data requirements for the triazole - based metabolites under DP# 327788 (4/25/06, M. Dohert y). The supporting barley and wheat magnitude of the residue data consider herein were submitted prior to the HED issued guidance, and do not include any triazole metabolite data. This issue will not be discussed further. It is important to note that the first food use of difenoconazole, which was reviewed under a previous petition, PP#2E4051 ( DP# s 172067 and 178394, 10/26 /92, R. Lascola), was for the establishment of import tolerances in/on barley , rye, and wheat resulting from seed treatment uses of difenoconazole o n rye and wheat at 27.2 g ai/100 lb seed and on barley at 10.2 g ai/100 lb seed. Hence, taking into account the proposed maximum seed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley , rye, wheat, and triticale (both domestic (Dividend® Fungicide (EPA Reg. No. 100 - 740) ) and non - domestic (use inform ation previously provided under PP#2E4051 ( DP# s 172067 and 178394, 10/26/92, R. Lascola) ), HED has evaluated the available data for the following maximum seed treatment use rates: 27.2 g ai/100 lb seed for the rye, wheat, and triticale and 11 g ai/100 lb seed for barley and oats. The nature of the residue in plants is understood based on acceptable plant metabolism studies reflecting foliar applications in canola, grape, potato, tomato, and wheat, and seed treatment in wheat. HED concludes that the res idue of concern for both tolerance enforcement and risk assessment for crops included in this petition is difenoconazole per se . The nature of the residue in livestock is understood based on acceptable goat and hen metabolism studies. The residues of con cern for both tolerance setting and risk assessment for livestock commodities are difenoconazole per se and its metabolite CGA - 205375. An adequate tolerance enforcement method, Method AG - 575B, is available for crop commodities. The method determines residues of difenoconazole per se in/on crop commodities by gas chromatography

with nitrogen - phosphorus detection (GC/NPD). The method limi ts of quantitation (L OQs) range from 0.01 - 0.05 ppm. A confirmatory GC method with mass - selective detection (MSD) is also available for crop commodities. An adequate tolerance enforcement method, Method REM 147.07b, is available for livestock commodities. The method determines residues of difenoconazole and CGA - 205375 in livestock commodities by

liquid chromatograph y with tandem mass spectrometry detection (L C/MS/MS). The method LOQs are 0.01 ppm (for each analy te) for livestock tissues and 0.005 ppm (fo r eachDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 4 of 23 anal yt e) for milk. Adequate confirmatory methods, Method AG - 544A and Method REM 147.06, are available for the determination of residues of difenoconazole and CGA - 205375, respectivel y, in livestock commodities. Adequate cattle and poultry feeding studies are available for difenoconazole , and tolerances for difenoconazole residues of concern in livestock commodities were recently re - evaluated in conjunction with a petition for tolerances in/ on carrots, chickpeas, so ybeans, stone fruits, strawberries, and turnip greens (PP# 9F7676; DP# 378829, 2/23/11, B. Cropp - Kohlligian). Using the Agency ’s most recent guidance on constructing reasonably balanced livestock diets (ChemSAC memo, 6/30/08), the maximum dietary burdens (MDB) of livestock for difenoconazole residues were calculated to be 6.0 ppm for beef cattle, 1.6 ppm for dairy c attle , 0.09 ppm for swine, and 0. 11 ppm for poultry . These diets included barley and wheat livestock feedstuffs. Altho ugh there are several livestock f eedstuffs associated with the proposed uses on oats and rye, the reviewer has determined that they w ill not increase the dietary exposure of livestock to difenoconazole residues and that reassess ment of livestock tolerances is not required for th is petition. No oats and rye field trial data were submitted with the current petition (PP#0F7785). Instead the petitioner has requested the translation of previously submitted wheat and barley field trial data reflecting seed tre atment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye. Given the deliberations by ChemSAC (meetings of 11/25/09 and 9/1/10) on this subject, the requested translations are deemed appropriate since the seed treatment uses under consideration are substantially similar to those reflected in the available wheat and barley

field trial data and the resulting residues were either nondetectable (grain and hay), negligible (straw), or very low (forage) in/on the raw agricultural commodities (RACs) of wheat and barley . Hence, barley grain data may

be translated to oat grain since barley and oat grains are kernels (caryopsis) plus hulls (lemma and palea); wheat grain data may be translated to rye grain since rye and wheat grains are kernels with hulls removed. Wheat forage data may be translated to oat and rye forage. Wheat straw data may be translated to oat and rye straw. Wheat hay

may be translated to oat hay . For grains, n o detectable residues of difenoconazole were found in/on any of the wheat and barley grain samples collected from the supporting field trials. Most of these data were collected with the current enforcement method, Method AG - 575B (GC/NPD), or a substantially similar precursor (Method AG - 575 ), having a LOQ of 0.01 ppm in/on grain. However, a limited number of the older wheat grain data submitted with the first food use of difenoconazole (PP#2E4051; DP# s 172067 and 178394, 10/26/92, R. L ascola) from trials conducted in Europe (France (5 trial s) and Germany (4 trials)) were generated with other, less sensitive data collection methods, precipitating the earlier recommendation to establish tolerances for residues of difenoconazole in/on barley grain, rye grain, and wheat grain at the higher curre nt levels, 0.1 ppm. These established tolerance levels are based primarily on wheat grain samples from trials conducted in France at the maximum seed treatment use rate for wheat (27.2 g ai/100 lb seed) in which residues in/on grain samples were reported as nondetectable, <0.02 ppm; below the reported “limit of sensitivity” of the data collection method (0.02 ppm in/on grain). The originalDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 5 of 23 HED reviewer of these data ( PP#2E4051; DP# s 172067 and 178394, 10/26/92, R. L ascola ) determined that the demonstrated limit of detection, 0.08 ppm in/on grain, was higher than the reported “limit of sensitivity” (0.02 ppm in/on grain) based on the recovery data; hence, a tolerance level of 0.1 ppm was established. Having re - evaluation the chromatograms for the grain samples collected from the trials conducted in France and Germany , the reviewer finds that residues of difenoconazole in/on the treated grain samples were not greater than those in/on the associated untreated grain samples. Hence, taking into account all of the available evidence, the reviewer finds that no detectable residues of difenoconazole ( i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), are expected in/on the grains of barley , oats, rye, and wheat from the propo sed and/or existing maximum seed treatment use rates of difenoconazole on these grains. Therefore, the tolerances proposed b y the petitioner for oat grain (0.1 ppm) and rye grain (0.1 ppm) are too high; tolerances of 0.01 ppm are appropriate . For hay and straw, h aving re - evaluated the previously submitted wheat hay and straw data, the reviewer finds that residues of difenoconazole are not expected to exceed 0.05 ppm (the LOQ of the current enforcement method for hay and straw) in/on barley

hay , barley straw, oat hay , oat straw, rye straw, wheat hay , and wheat straw from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains. Therefore, the tolerances proposed b y the petitioner for oat hay

(0.1 ppm), oat straw (0 .1 ppm), rye straw (0.1 ppm), and wheat hay (0.1 ppm) are too high; tolerances of 0.05 ppm are appropriate. For forage, having re - evaluated the previousl y submitted wheat forage data, and using the OECD MRLcalculator, the reviewer finds that the availabl e data will support a tolerance of 0.15 ppm in/on oat, rye, and wheat forages. Residues of difenoconazole are not expected to exceed 0.15 ppm in/on oat, rye, and wheat forages from the proposed and/or existing maximum seed treatment use rates of difenocon azole on these grains. Therefore, the tolerances proposed b y the petitioner for oat forage (0.1 ppm) and rye forage (0.1 ppm) are too low; tolerances of 0.15 ppm are appropriate. Pregrazing and/or preharvest intervals are not needed for barley forage whi ch is not considered a raw agricultural commodity (RAC) of barley . Pregrazing and/or preharvest intervals are not needed for oat, rye, and wheat forages given that the use pattern is limited to seed treatment and the supporting wheat forage data collected at 34 - to 61 - day s after planting , which were used to set tolerances in/on oat , rye , and wheat forages, reasonably reflect the shortest period possible between planting and grazing/harvesting these forages. No oat and rye processing data were submitted wi th the current petition and none are available. A wheat processing study (MRID 42090055) was previously submitted and reviewed b y HED ( PP#2E4051; DP# s 172067 and 178394, 10/26/92, R. L ascola). Spring wheat seed was treated at 23.2 g ai/100 lb seed and pl anted . Later the wheat was also treated twice foliarly with an emulsifiable concentrate (E C ) formulation of difenoconazole at 100 g ai/A to attempt to achieve detectable residue in/on grain. [Note: Difenoconazole is not registered in the U.S. for foliar uses on cereal grain s . ] Wheat grain was harvested 28 day s after the last foliar treatment and processing into bran, middlings, shorts and germ, and patent flour. No residues of difenoconazole (<0.01 ppm) were detected in the grain and processed commodities. These data may be translated to the processed commodities of barley , oats, and rye given the nature of theDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 6 of 23 subject wheat processing study which was conducted at an exaggerated rate resulting in nondetectable residues in both th e RAC and processed commodities and given the use pattern for these cereal grains. Hence, b ased on the available wheat processing data , tolerances in the processed commodities of barley , oats, rye, wheat, and triticale are not needed for the seed treatment uses under consideration. Previously

submitted confined rotational crop data are adequate to support the proposed seed treatment uses of difenoconazole on oats and rye. A 30 - day plantback interval is appropriate for the proposed uses on these crops. [Note: Additional confined rotational crop data have been required to support foliar uses of difenoconazole but are not required to support the proposed seed treatment uses. These data have been submitted (MRID 48203402) and are under review in HED (D3 82946).] Codex maximum residue limits ( MRL s ) for residues of difenoconazole have been established . H owever, since no Codex MRL s have been established for residues of difenoconazole in/on oat commodities , rye commodities , and wheat hay , harmonization with Codex is not an issue . Canadian MRL s for residues of difenoconazole have been established at 0.01 ppm for oat grain and 0.01 ppm for rye grain and h armonization with these established C anadian MRL s is recommended. Mexican MRL s for residues of difenoconazole have been established; however, no Mexican MRL s have been established for an y of the cereal grain commodities . **I. CONCLUSIONS**  HED has examined the residue chemistry database for difenoconazole and pending submission of a revised Section F (see requirements under Proposed Tolerances), there are no residue chemistry issues that would preclude granting a registration for the requested seed treatment uses of difenoconazole on oats and rye or establishment of tolerances for r esidues of difenoconazole only in/on the raw agricultural commodities listed below. Furthermore, pregrazing restrictions on forages are not needed for the requested seed treatment uses (see Directions for Use).

Oat, grain ................................ ................................ .............. 0.0 1 ppm Oat, forage ................................ ................................ ............ 0.1 5 ppm Oat, hay ................................ ................................ ................ 0.05 ppm Oat, straw ................................ ................................ ............. 0.05 ppm Rye, grain ................................ ................................ ............. 0.0 1 ppm Rye, forage ................................ ................................ ........... 0.1 5 ppm Rye, straw ................................ ................................ ............ 0.0 5 ppm Wheat, hay ................................ ................................ ........... 0.05 ppm **Note s**  **to the**  **PM: (1)**  **The recommended tolerance for rye grain (0.01 ppm) should replace the existing import tolerance for rye grain (0**  **.1 ppm).**Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 7 of 23 **(2) H**  **aving re -**  **evaluated the available barley and wheat**  **magnitude of the residue data**  **which were translated to support the proposed seed treatment uses of difenoconazole on oats and rye,**  **HED finds**  **that , with regards to the maximum seed treatment uses**  **of difenoconazole on barley**  **, wheat, and triticale : (i)**  **the existing permanent tolerances for residues of difenoconazole in/on barley hay (0.05 ppm)**  **and barley str**  **aw (0.05 ppm) are appropriate; (ii)**  **the exi**  **sting permanent tolerance for residues of difenoconazole in/on**  **barley grain may be decreased**  **from 0.1 ppm to 0.0 1**  **ppm to harmonize with the existing**  **Canadian MRL (iii) the existing permanent tolerance for residues of difenoconazole in/on**  **wheat grain may be**  **decreased from 0.1 ppm to 0.02 ppm**  **to harmonize with the existing C**  **odex MRL**  **; (iv) the existing permanent tolerance for residues of difenoconazole in/on**  **wheat straw may be decreased**  **from 0.1 ppm to 0.05 ppm consistent with the**  **tolerances recommended for**  **oa t and rye straw**  **; and (v) the existing permanent tolerance for residues**  **of difenoconazole in/on wheat forage should**  **be increased**  **from 0.1 ppm to 0.15 ppm consistent with the**  **tolerances recommended for oat and rye forages**  **.** 860.1200 Directions for Use

 P regrazing restrictions are not needed for barley , oat, rye, and wheat forages and should be removed from the proposed and currentl y registered Dividend® Fungicide (EPA Reg. No. 100 - 740) labels. [Note: Pregrazing restrictions were not included in Section B of petition PP#0F7785.] 860.1550 Proposed Tolerances

 The proposed tolerances should be revised to reflect the recommended tolerance levels and correct commodit y definitions as specified in Table 3 .Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 8 of 23 **II. DETAILED CONSIDERATIONS**  **Background** Difenoconazole is a broad spectrum fungicide belonging to the triazole group of fungicides (Group 3) that acts by

inhibiting sterol demeth yl ation . The chemical structure s and nomenclature of difenoconazole are presented in Table 1 and the phy sicochemical properties of the technical grade of difenoconazole are presented in Table 2. **Table 1. Structures and**  **Nomenclature** . Chemical structure of difenoconazole

Common name Difenoconazole Com pany experimental name CGA - 169374 IUPAC name 1 - ({2 - [2 - chloro - 4 - (4 - chlorophenoxy)phenyl] - 4 - methyl - 1,3 - dioxolan - 2 - yl}methyl) - 1H - 1,2,4 - triazole CAS name 1 - [[2 - [2 - chloro - 4 - (4 - chlorophenoxy)phenyl] - 4 - methyl - 1,3 - dioxolan - 2 - yl]methyl] - 1H - 1,2,4 - triazole CAS registry number 119446 - 68 - 3 End - use product s (EP) Dividend ® Fungicide , 3.1 lb/gal FS ( EPA Reg. No. 100 - 740) . O O O Cl N N N C H 3 ClDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 9 of 23 **Table 2. Physicochemical Properties of**  **Difenoconazole .**  Parameter Value Reference Melting point 78.6 oC DP#s 172067 and 178394, 10/2 6 /92, R. Lascola pH 6 - 8 at 20 oC (saturated solution) Density 1.37 g/cm3 at 20 oC Water solubility 3.3 ppm at 20 oC Solvent solubility g/100 mL at 25 oC : n - hexane: 0.5 1 - octanol: 35 toluene: 77 acetone: 88 ethanol: 89 Vapor pressure 2.5 x 10 - 10 mm Hg at 25 oC Dissociation constant, pK a 1.1 for pure grade (99.3% ± 0.3%) difenoconazole in water (with 4% methanol) at 20oC DP# 375159, 5/26/10, B. Cropp Kohlligian Octanol/water partition coefficient, Log(KOW ) 4.2 at 25 oC DP#s 172067 and 178394, 10/26/92, R. Lascola UV/visible absorption spectrum  max at about 200 and 238 nm (in methanol at 26 oC) PMRA Proposed Regulatory Decision Document on Difenoconazole, 4/14/99 (PRDD99 - 01)Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 10 of 23 **860.1200 Directions for Use** Residue Chemistry Memo : PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola Dividend ® Fungicide (EPA Reg. No. 100 - 740 ; EPA accepted 10/22/10 ) is a sy stemic seed dressing , formulated as a flowable concentrate for seed treatment (FS) containing 3.1 lb/gal (32.8%) of difenoconazole , which controls or suppresses certain seed - borne, soil - borne, and earl y season foliar diseases of wheat, barley, and triticale , and certain seed and seedling diseases of canola, sweet corn, and cotton . Applications are made as w ater - based slurry though standard slurry or mist - ty

pe seed treatment equipment. Tank mixed with other seed treatment products is permitted. The use of an EPA - approved dye or colorant that imparts an unnatural color to seed is required . Also bags contain ing treated seed are to be labeled with the following restrictive language: (1) Do not use for feed, food, or oil purposes ; (2) Stor e away from feeds and foodstuffs ; (3) Green wheat or triticale forage may not be grazed until 55 day s after planting ; (4) Green barley

forage may

not be grazed until 30 day s after planting ; and (5) Do not plant any crop other than those on this label within 30 days to fields in which treated seeds were planted. In conjunction with the current petition ( PP#0F7785 ) Sy ngent a is requesting an amended registration for Dividend ® Fungicide (EPA Reg. No. 100 - 740) to add use as a seed treatment on oats and rye at 11 g ai/100 lb seed, the same maximum use rate it is currently registered on barley , wheat, and triticale . The petitioner has submitted a Section B reflecting proposed use rates for the 3.1 lb/gal FS formulation ( Dividend ® Fungicide; EPA Reg. No. 100 - 740 ) on oats and rye without any

additional restrictive language ; supporting draft labeling (dated 9/20/10) wa s also submitted . Consistent with the currentl y regist ered grazing restrictions for green wheat and triticale forage, the proposed label restricts the grazing of green oats and rye forage until 55 day s after planting. It is important to note that non - domestic seed treatment uses of difenoconazole on barley , rye, and wheat have been previously considered b y the Agency and are different from the registered/proposed domestic use rates . T he f irst food use of difenoconazole, which was reviewed under a previous petition ( PP#2E4051 ; DP# s 172067 and 178394, 10/26/92, R. Lascola), was for the establishment of import tolerances in/on barley , rye, and wheat resulting from seed treatment uses of difenoconazole o n barley reported to the Agency at 10.2 g ai/100 lb seed , and on rye and wheat at 27.2 g ai/100 lb seed. While the reported non - domestic maximum seed treatment use rate on barley is slightl y less than the currentl y registered domestic maximum use rate, the reported non - domestic maximum seed treatment us e rates on rye and wheat are roughl y 2.5x higher than the proposed domestic maximum use rate on rye and the currently registered domestic maximum use rate on wheat. Conclusions . The proposed use directions are adequate to allow evaluation of the residu e data relative to the proposed use s of difenoconazole on oats and rye . No oats and rye field trial data were submitted with the current petition (PP#0F7785). Instead the petitioner has requested the translation of previousl y submitted wheat and barley f ield trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment uses of difenoconazole on oats and rye.Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 11 of 23 The maximum proposed seed treatment use rate for oats and rye is 11 g ai /100 lb seed, the same maximum use rate currently registered for barley , wheat, and triticale. Based on the use of an EPA - approved dye or colorant to impart an unnatural color to the treated seed and the equipment used for application, the use appears lim ited to commercial facilities although this is not specified on the proposed Dividend ® Fungicide (EPA Reg. No. 100 - 740) label. It is important to note that non - domestic seed treatment uses of difenoconazole on barley , rye, and wheat have been previously c onsidered by

the Agency

and are different from the registered/proposed domestic use rates. The first food use of difenoconazole, which was reviewed under a previous petition (PP#2E4051; DP# s 172067 and 178394, 10/26/92, R. Lascola), was for the establishm ent of import tolerances in/on barley , rye, and wheat resulting from seed treatment uses of difenoconazole o n barley reported to the Agency

at 10.2 g ai/100 lb seed and on rye and wheat at 27.2 g ai/100 lb seed. T aking into account the proposed maximum se ed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley , rye, wheat, and triticale (both domestic (Dividend ® Fungicide (EPA Reg. No. 100 - 740) and non - domestic (use information previously

provided under PP#2E4051 ( DP# s 172067 and 178394, 10/26/92, R. Lascola) ) , HED will evaluate available data for the following maximum seed treatment use rates: 27.2 g ai /100 lb seed for the rye, wheat, and triticale and 1 1 g ai/100 lb seed for barley and oats . B ased on the available data, p regrazing restrictions are not needed for barley , oat, rye, and wheat forages and should be removed from the proposed and currently registered Dividend® Fungicide (EPA Reg. No. 100 - 740) labels.Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 12 of 23 **860.1500 Crop Field Trials** Residue Chemistry Memos: PP#2E4051; DP#s 172067 and 178394, 10/26/92, R. Lascola (MRIDs 42090055 and 42090056) PP#2F4107; DP# s 248285 and 248419 , 10/28/98, S. Chun (MRID 44602001) PP#6F4748; DP# 228403 , 9/23/96, G. Kramer (MRID 44056001) No oats and rye field trial data were submitted with the current petition (PP#0F7785). Instead the petitioner has requested the translation of available acceptable wheat and barley field trial data reflecting seed treatment uses of difenoconazole to suppo rt the proposed seed treatment uses of difenoconazole on oats and rye. The available wheat and barley field trial data reflecting seed treatment use of difenoconazole have been re - evaluated and are discussed below. Wheat field trial data (MRIDs 4209055 and 4209056) conducted in the U.S. and Europe were submitted for the first food use of difenoconazole and reviewed under a previous petition, PP#2E4051 ( DP# s 172067 and 178394, 10/26/92, R. L ascola). Later , a new and substantially complete set of wheat fi eld trial data (MRID 44602001) were submitted under another petition, PP#2F4107 (DP#s 248285 and 248419, 10/28/98, S. Chun) . Barley field trial data (MRID 44056001) were submitted under yet another petition, PP#6F4748 ( DP# 228403, 9/23/96, G. Kramer). Related d ata deficiencies were addressed over a period of several y ears under a number of HED reviews. **Wheat Fi**  **eld Trials** MRID 42090055

– Data previously submitted and reviewed b y HED under PP#2E4051 (DP# s 172067 and 178394 , 10/26/92, R. Lascola ) Sprin g wheat seed was treated with difenoconazole at either 11 or 23.2 g ai/100 lb seed and planted at 3 sites (ND (1), WA (1), and MT (1) ) Spring wheat seed was treated with difenoconazole at 11 g ai/100 lb seed and planted at 3 sites ( MN (1), SD (1), and IL (1)). Plants were grown to maturity ; forage samples w e re collected 54 - 92 day s after planting, and grain and straw samples w e re collected 81 - 119 day s after planting . Samples were analyzed with an acceptable data collection method ( Method AG - 575 (GC/NPD) ) ; based on recovery data the demonstrated LOQ was 0.01 ppm for grain, forage , and straw . N o detectable residues (<0.01 ppm) of difenoconazole were found in/on an y of the grain or straw samples. No detectable residues (<0.01 ppm) were found in/on forage i n 5 of the 6 trials; only the SD trial , conducted at 11 g ai/100 lb seed, showed any detectable residues ( 0.02 ppm). Winter wheat seed was treated with difenoconazole at either 9.5 or 21.2 g ai/100 lb seed and planted at 5 sites (NY (1) , AR (1) , TX (1) , O K (1) , and WA (1) ). Winter wheat seed was treated with difenoconazole at 9.5 g ai/100 lb seed and planted at 1 site ( KS (1) ). Spring wheat seed was treated with difenoconazole at 9.5 or 21.2 g ai/100 lb seed and p lanted at 2 sites (AZ (1) and CA (1) ) . T his corresponds to 7 trials in the following regions: Region 1 (1 trial), Region 4 (1 trial), Region 6 (2 trials), Region 8 (1 trial), Region 10 (2 trials), and Region 11 (1 trial). F orage samples were collected 56 - 67 day s after planting, and grain and s traw samples were collectedDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 13 of 23 149 - 328 day s after planting. Forage samples from CA, OK, and WA were not viable for various reasons. Samples were analyzed with an acceptable data collection method ( Method AG - 575 (GC/NPD) ) ; based on recovery data the demonstr ated L OQ was 0.01 ppm for grain, forage, and straw . No detectable residues (<0.01 ppm) of difenoconazole were found in/on any of the samples with the following exceptions: (1) for forage, detectable residues ( ≤0.02 ppm) were found at the NY and AR trials and (2) for straw, detectable residues ( ≤0.03 ppm) were found at the AR , TX, and AZ trial s . MRID 42090056

– Data previously submitted and reviewed b y HED under PP#2E4051 (DP#s 172067 and 178394 , 10/26/92, R. Lascola ) European Trials. Residues trials were conducted in France (5 trials) and German y (4 trials) using wheat, barley , or rye seed treated with difenoconazole. In France, wheat seeds were treated at 8.2 g ai/100 lb seed (1 trial) , 16.4 g ai/100 lb seed (1 trial) , or 27.3 g ai /100 lb seed (3 trials) and grain samples were collected . In Germany, wheat seed (1 trial) , barley seed (2 trials) , and rye seed (1 trial) were treated at 27.3 g ai/100 lb seed and grain, forage, and straw samples were collected . No detectable residues o f difenoconazole were reportedl y found in/on any of the grain and straw samples; detectable residues of difenoconazole were reportedly found in/on the rye forage sample and one of the two barley forage samples from the trials conducted in German y (reported as 0.02 ppm and 0.03 ppm , respectivel y). Grain samples from the trials in France were analyzed with Method REM 07/86 (GC/ECD) with a reported “limit of sensitivity” of 0.02 ppm in/on grain ; the original HED reviewe r determined that the d emonstrated lim it of detection was 0.08 ppm in/on grain based an evaluation of the recovery data . Grain samples from the trials in German y were anal yz ed with a modified version of Method AG - 537 (GC/ECD) or a modified version of Method AG - 514, which is essentially identical to Method AG - 537 , with a reported “limit of sensitivity” of 0.02 or 0.03 ppm in/on grain; the original HED reviewer determined that the demonstrated LOQ was 0.05 ppm in/on grain . MRID 44602001

– Data previously submitted and reviewed b y HED und er PP#2F4107 (DP#s 248285 and 248419 , 10/28/98, S. Chun ) Wheat seed was treated with difenoconazole at 10.9 g ai /100 lb seed and planted at 15 sites ( OK (2), TX (1), NC (1), MT (1), KS (2), CO (1), ND (1), SD (1), AR (1), ID (1), MO (1), MN (1), and NE (1) ) . Wheat seed was treated with difenoconazole at 21.8 g ai/100 lb seed and planted at 3 sites (OK (1), KS (1), and (ND (1)). F orage samples were collected 34 - 112 day s after planting, additional forage samples were collected 164 - 241 day s after planting (11 out of 15 trials) , hay samples were collected 48 - 281 day s after planting, and grain and straw samples were collected 83 - 322 day s after planting. Samples were anal yz ed with an acceptable data collection method ( Method AG - 575B (CG/NPD) ); based on recov ery data the demonstrated LOQ was 0.01 ppm for grain and 0.05 ppm for forage, hay , and straw . No detectable residues of difenoconazole were found in/on any

of the grain (<0.01 ppm) , straw (<0.05 ppm) , and hay (<0.05 ppm) samples. Residues of difenoconazo le were detectable in/on 4 of the 52 forage samples collected from theDifenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 14 of 23 trials conducted at 10.9 g ai/100 lb seed; they ranged from <0.05 to 0.077 ppm . No detectable residues of difenoconazole were found in/on the forage samples from the 3 trials conducted at 21.8 g ai/100 lb seed . [Note: The trials which found detectable residues of difenoconazole in/on forage were only

conducted at the lower, 10.9 g ai/100 lb seed, treatment rate.] **Barley Fi**  **eld Trials** MRID 4 4 056001

– Data previously submitted and reviewed b y HED under PP#6F4748 (DP# 228403 , 9/23/96, G. Kramer) Barley seed was treated with difenoconazole at 10.9 g ai/100 lb seed and planted at 9 sites (ID (1), ND (1), MN (1), MT (1), ND (1), SD (1), VA (1), CO (1), and CA (1)). Barley seed was treated with difenoconazole at 21.8 g ai/100 lb seed and planted at 1 site (ND). F orage samples were collected 32 - 152 day s after planting; hay samples were collected 54 - 191 day s after planting ; and grain and straw sampl es were collected 89 - 224 day s after planting . Samples were anal yz ed with an acceptable data collection method (Method AG - 575B (CG/NPD)); based on recovery data the demonstrated LOQ was 0.01 ppm for grain and 0.05 ppm for forage, hay , and straw. No detect able residues of difenoconazole were found in/on any of the grain (<0.01 ppm), forage (<0.05 ppm), straw (<0.05 ppm), and hay (<0.05 ppm) samples. **Conclusions:** No oats and rye field trial data were submitted with the current petition (PP#0F7785). Instea d the petitioner has requested the translation of previously submitted wheat and barley

field trial data reflecting seed treatment uses of difenoconazole to support the proposed seed treatment use s of difenoconazole on oats and rye . Given the deliberation s by ChemSAC (meetings of 11/25/09 and 9/1/10) on this subject, the requested translation s are deemed appropriate since the seed treatment uses under consideration are substantially similar to those reflected in the available wheat and barley field trial d ata and the resulting residues were either nondetectable (grain and hay), negligible ( a few detectable residues in/on some straw samples below the LOQ of the current enforcement method for straw ), or very low ( a few detectable residues in/on some forage samples ) in/on the raw agricultural commodities (RACs) of wheat and barley . Hence, b arley grain data may be translated to oat grain since barley and oat grains are kernels (caryopsis) plus hulls (lemma and palea); wheat grain data may be translated to rye grain since rye and wheat grains are kernels with hulls removed. Wheat forage data may be translated to oat and rye forage. Wheat straw data may be translated to oat and rye straw. Wheat hay data may be translated to oat hay . Taki ng into account the proposed maximum seed treatment use rates of difenoconazole on oats and rye and the existing maximum seed treatment use rates on barley , rye, and wheat (both domestic (Dividend ® Fungicide (EPA Reg. No. 100 - 740) and non - domestic (use information previously provided under PP#2E4051 ( DP# s 172067 and 178394, 10/26/92, R. L ascola) ), HED will need to evaluate the available data for the following maximum seed treatment use rates: 27.2 g ai/100 lb seed for the rye and wheat and 11 g ai/100 lb seed for barley and o ats.Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 15 of 23 Grains. No detectable residues of difenoconazole were found in/on any of the wheat and barley grain samples collected from the supporting field trials. Most of these data were collected with the current enforcement method, Method AG - 575B (GC/NPD) , or a substantially similar precursor (Method AG - 575), having a LOQ of 0.01 ppm in/on grain . However, a limited number of the older wheat grain data submitted with the first food use of difenoconazole (PP#2E4051; DP# s 172067 and 178394, 10/26/92, R. Lascola) from trials conducted in Europe (France (5 trials) and Germany (4 trials)) were generated with other, less sensitive data collection methods , precipitating the earlier recommendation to establish tolerances for residues of difenoconazole in/on barley grain, rye grain, and wheat grain at the higher current levels, 0.1 ppm . These established tolerance levels are based primarily on wheat grain samples from trials conducted in France at the maximum seed treatment use rate for wheat (27.2 g ai/100 lb s eed) in which residues in/on grain samples were reported as nondetectable, <0.02 ppm ; below the reported “limit of sensitivity” of the data collection method ( 0.02 ppm in/on grain ) . T he original HED reviewer of these data ( PP#2E4051; DP# s 172067 and 17839 4, 10/26/92, R. L ascola ) determined that the demonstrated limit of detection , 0.08 ppm in/on grain , was higher than the reported “limit of sensitivity” (0.02 ppm in/on grain) based on the recovery data ; hence, a tolerance level of 0.1 ppm was established. Having r e - evaluat ion the chromatograms for the grain samples collected from the trials conducted in France and German y, the reviewer finds that residues of difenoconazole in/on the treated grain samples were not greater than those in/on the associated untreated grain samples . H ence, taking into account all of the available evidence, the reviewer finds that no detectable residues of difenoconazole ( i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), ar e expected in/on the grains of barley , oats, rye, and wheat from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains. Hay and Straw. Available wheat straw data were translated to oat and rye straw. Available wheat hay

data were translated to oat hay . Available barley hay and straw data are considered supporting data. Having re - evaluated the previously submitted wheat hay and straw data, the reviewer finds that residues of difenoconazole are not expected to exceed 0.05 ppm ( the LOQ o f the current enforcement method for hay and straw) in/on barley

hay , barley

straw, oat hay , oat straw, rye straw, wheat hay , and wheat straw from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains . Forage. Available wheat forage data were translated to oat and rye forage. Available barley forage data are considered supporting data . Having re - evaluated the previously submitted wheat forage data, and using the OECD MRL calculator, the reviewer finds that the available data will support a tolerance of 0.15 ppm in/on rye, oat, and wheat forages. The tolerance calculation is presented in Appendix I . The wheat forage field trial data selected for inclusion in the OECD MRLcalculat ion was a large dataset (24 field trials) reflecting the maximum p roposed seed treatment use rate for oats and rye (11 g ai/100 lb seed), the same maximum use rate currently regist ered in the U.S. for barley , wheat,Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 16 of 23 and triticale, and reflecting foraging/harvesting 34 - to 61 - day s after planting treated seed . Taken as a whole, the available wheat forage data indicate that residues of difenoconazole are not expected to exceed 0.15 pp m in/on rye, oat, and wheat forages from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains. Pregrazing and/or preharvest intervals are not needed for barley forage which is not considered a raw agricultural commodity (RAC) of barley . Pregrazing and/or preharvest intervals are not needed for oat, ry e, and wheat forages given that the use pattern is limited to seed treatment and the supporting wheat forage data collected at 34 - to 61 - day s after planting , whic h were used to set tolerances in/on oat , rye, and wheat forages, reasonabl y reflect the shortest period possible between planting and grazing/harvesting these forages. [Note: Agricultural practices information provided via personal communication with B. Schneider of HED. R eference: http://northerngraingrowers.org/wp - content/uploads/managing small - grains - for - forage.pdf ] Furthermore, a ccording to the Agency ’s most recent guidance on constructing reasonabl y balanced livestock diets (ChemSAC memo, 6/30/08), oat, rye, and wheat forages are fed to high - production dairy cattle only

and the most recently constructed dairy cattle diet (PP# 9F7676; DP# 378829, 2/23/11, B. Cropp - Kohlligian) included wheat forage which contributed little (0.04 ppm) to the 1.6 ppm maximum dietary burden ( MDB ) for dairy

cattle which was dominated b y the contribution of wet apple pomace (1.13 ppm). Hence, even a relativel y signific ant increase in residues of difenoconazole in/on oat, rye, and wheat forage s is expected to have no significant impact on the MDB for dairy cattle.Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 17 of 23 **860.1550 Proposed Tolerances** Tolerances for plant commodities are established under §180.475(a)(1) , and are expressed in terms of difenoconazole per se . The tolerance s proposed by S yn genta are also expressed in terms of difenoconazole per se and are listed in Table 3 along with the tolerance levels recommended b y HED and corrected commodity definitions. No new residue chemistry data were submitted with the current petition. Instead available barley and wheat magnitude of the residue data were translated to support the proposed uses on oats and rye. These data were re - evaluated primarily for the purposes of harmonization and secondarily for the purposes of setting tolerances in accordance with current guidance. See Table 3 for details. Based on the available wheat processing data, tolerances in the processed commodities of barley , oats, rye, wheat, and triticale are not needed for the seed treatment uses under consideration. Codex maximum residue limits ( MRL s) for residues of difenoconazole have been established . Codex MRL s for residues of difenoconazole per se have been established at 0. 02 ppm (absent at the limit of quantitation) for wheat grain and 3 ppm for wheat straw and fodder, dry ; these levels are based on a foliar use of difenoconazole which is not reg istered in the U.S. S ince no Codex MRL s have been established for residues of difenoconazole in/on oat commodities, rye commodities, and wheat hay , harmonization with Codex is not an issue. Canadian MRLs for residues of difenoconazole per se have been es tablished at 0.01 ppm for barley grain; 0.01 ppm for oat grain; 0.01 ppm for rye grain; and 0.1 ppm for wheat grain. H armonization with the established C anadian MRL s of 0.01 ppm for residues of difenoconazole in/on oat grain and rye grain is recommended. Mexican MRL s have been established for difenoconazole; however, no Mexican MRL s have been established for an y cereal grains . **Table 3**  **. Tolerance Summary for Difenoconazole.**  **Comm odity**  **Proposed**

**Tolerance (ppm)**  **Recommended**

**Tolerance (ppm)**  **Correct Commodity Definition;** 

**Comments** Oat s , grain 0.1 0.01 Oat, grain. The proposed tolerance is too high. Based on the translation and re - evaluation of available barley grain data, no detectable residues of difenoconazole per se are expected in/on oat grain from the maximum seed treatment use under consideration. Therefore, the tolerance should be established at the limit of quantitation (LOQ) of the current enforcement method, 0.01 ppm in/on grain; a level consistent with the es tablished Canadian MRL in/on the same commodity. Oat s , forage 0.1 0.15 Oat, forage. Based on the translation and re - evaluation of available wheat forage data, and using the OECD MRL calculator, a tolerance of 0.15 ppm is appropriate for the maximum seed treatment use under consideration.Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 18 of 23 **Table 3**  **. Tolerance Summary for Difenoconazole.**  **Comm odity**  **Proposed**

**Tolerance (ppm)**  **Recommended**

**Tolerance (ppm)**  **Correct Commodity Definition;** 

**Comments** Oat s , hay 0.1 0.05 Oat, hay. Based on the transl ation and re - evaluation of available wheat hay data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on hay, for the maximum seed treatment use under consideration. Oat s , straw 0.1 0.05 Oat, straw. Based on the translation and re - evaluation of available wheat straw data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on straw, for the maximum seed treatment use under consideration. Ry e, grain 0.1 0.01 Based on the translation and re - evaluation of available wheat grain data, no detectable residues of difenoconazole per se are expected in/on oat grain from the maximum seed treatment use under consideration. Therefore, the toler ance should be established at the limit of quantitation (LOQ) of the current enforcement method, 0.01 ppm in/on grain; consistent with the established Canadian MRL in/on the same commodity. **Note: The recommended tolerance for rye grain (0.01 ppm) should**  **replace the existing import tolerance for rye grain (0.1 ppm** **).** Ry e, forage 0.1 0.15 See comments above under Oat, forage. Ry e, straw 0.1 0.05 See comments above under Oat, straw . Wheat, hay 0.1 0.05 Based on the re - evaluation of available wheat hay data, residues of difenoconazole are not expected to exceed the LOQ of the current enforcement method, 0.05 ppm in/on hay, for the maximum seed treatment use under consideration.

**R eferences**  DP#s: 172067 and 178394 Subject: PP#2E4051. CGA - 169374 (Difenoconazole, Dividend®) in Imported Wheat,

Barley , and Rye Grain. First Food Use. CBTS# 9029, 9895. From: R. L ascola To: J. Stone/C. Giles - Parker Dated: 10/22 /92 MRIDs: 42090001 - 42090004, 42090032 - 42090059, and 42303901Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 19 of 23 DP# : 228403 Subject: PP# 6F4748 . Difenoconazole (Dividend) in or on Barley , Oats, and Triticale.

Evaluation of Residue Data and Analy tical Methods. Case 28 7954 . Chemical 128847. CBTS# 17407 . From: G. Kramer To: C. Eiden/D. McCall Dated: 9/23 / 9 6 MRIDs: 4 4056001 DP# s : 248285 and 248419 Subject: PP# 2F4107. Dife noconazole (Dividend) in/on Wheat and Animal RACs.

Amendments of 7/8/98 and 7/30/98. Chemical 128847. From: S. Chun To: C. Giles - Parker/J. Bazuin Dated: 10/28/98 MRIDs: 4 4602001 - 44602001 and 44619401 DP# : 375159 Subject: Difenoconazole. Dissociation Constant in Water Data to Satisfy OPPTS 830.7370 Guideline Requirements. From: B. Cropp - Kohlligian To: Rosemary Kearns/Ton y Kish Dated: 5/26/10 MRID: 47957001 DP#: 378829 Subject: Difenoconazole. Application for Amended Section 3 Registration to Add Uses on

Carrots, Chickpeas, So yb eans, Stone Fruits (Group 12), Strawberries, and Turnip Greens. Summary

of Analy tical Chemistry

and Residue Data. From: B. Cropp - Kohlligian To: Rosemary Kearns/Ton y Kish Dated: 2/23/11 MRIDs: 47929801 - 47929805 **F. DOCUMENT TRACKING**  Petition Number: 0F7785 ( oat commodities, rye commodities, and wheat hay) DP Barcode(s): 384073 PC Code: 128847 Template Version September 2003Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 20 of 23 

### International Residue Limits

Difenoconazole (128847; 3/21/11) Summary of US and International Tolerances and Maximum Residue Limits Residue Definition : US Canada Mexico 2 Codex 3 40 CFR 180.475: Plant: difenoconazole, 1 - [2 - [2 - chloro 4 - (4 - chlorophenoxy)phenyl] - 4 - methyl - 1,3 - dioxolan - 2 - yl methyl] - 1H 1,2,4 - triazole Livestock: difenoconazole, 1 - [2 - [2 - chloro - 4 - (4 - chlorophenoxy)phenyl] - 4 - methyl - 1,3 - dioxolan - 2 - yl methyl] - 1H 1,2,4 - triazole, and its metabolite, CGA - 205375, 1 - [2 - chloro - 4 - (4 - chloro -phenoxy)phenyl] - 2 - [1,2,4]triazol - 1 - yl - ethanol 1 - [2 - [4 - (4 - chlorophenoxy) - 2 - chlorophenyl] - 4 - methyl - 1,3 - dioxolan - 2 - yl methyl] - 1 H 1,2,4 - triazole Plant commodities: difenoconazole Animal commodities: sum of difenoconazole and 1 - [2 - chloro - 4 - (4 - chloro -phenoxy) -phenyl] - 2 - (1,2,4 - triazol) - 1 - yl ethano), expressed as difenoconazole. The residue is fat soluble. Commodity 1 Tolerance (ppm) /Maximum Residue Limit (mg/kg) US Canada Mexico 2 Codex Oat, grain 3 0. 01 0.01 Oat, forage 0. 1 5 Oat, hay 0.05 Oat, straw 0.05 Ry e, grain 3 0. 01 0.01 Ry e, forage 0. 1 5 Ry e, hay 0.05 Ry e, straw 0.05 Wheat, hay 0. 05 Com pleted: M. Negussie; 03/28/2011 Subsequently Edited by B. Cropp - Kohlligian to Provide More Information With Additional Footnote 3 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 Having re - evaluated the available barley and wheat field trial data w hich were translated to support the proposed seed treatment uses of difenoconazole on oats and rye , the reviewer finds that no detectable residues of difenoconazole ( i.e., no residues above the LOQ of the current enforcement method, 0.01 ppm in/on grain), are expected in/on the grains of barley, oats, rye, and wheat from the proposed and/or existing maximum seed treatment use rates of difenoconazole on these grains. A lthough difenoconazole is not currently registered in the U.S. for use on rye, an import tolerance is currently established under 40 CFR §180.475 (a)(1) for residues of difenoconazole in/on rye grain at 0.1 ppm .Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 21 of 23 **Appendix I. Tolerance Assessment Calculations.**  For each of the crops listed below, the OECD MRL Calculator User Guide (SOP), along with the tolerance spreadsheet, was used for calculating recommended tolerances. As specified in the SOP, the tolerance calculation is in the region of the 95 th percentile of the underlying residue distribution, and is more likely to overest imate rather than underestimate the 95 th percentile. The rounding procedures specified in the SOP were also used. The OECD tolerance spreadsheet does not require the use of maximum - likelihood estimation (MLE) procedures for values <LOQ. Wheat forage The dataset us ed was large (24 samples) and consisted of field trial data representing seed treatment at a maximum seasonal application rate of 9.5 - 11 g ai/100 lb seed (consistent with the proposed domestic use rate) and reflecting 35 - 61 day PHI s . Sevent y - five percent of the data were censored. Data reflecting longer PHIs w ere excluded from the calculation; they were all censored data. [Note: Exclusion of data reflecting longer PHIs had no effect on the tolerance estimate.] The residue values that were entered into the OECD tolerance spreadsheet are provided in Table I - 1. Using the OECD spreadsheet (Figure I - 1) the appropriate tolerance is 0.15 ppm in/on wheat forage and , by translation , oat and rye forages . **Table I -**  **1. Residue data used to calculate tolerance for difenoconazole in/on wheat forage.**  Trial No. Trial Site

Trial ID Region PHI (days) Residues Found

(ppm) Average Residues

Used i n OECD MRL Calculations (ppm) **MRID 42090055 ;**  **Data previously reviewed by HED under PP#2E4051 (DP#s 172067 and 178394, 10/26/92, R. Lascola)**  **.** 1 ND MW - FR - 504 - 89 Region 5 60 <0.01, <0.01 <0.01 2 MT MW - FR - 503 - 89 Region 7 60 <0.01, <0.01 <0.01 3 MN MW - FR - 703 - 89 Region 5 61 <0.01, <0.01 <0.01 4 SD MW - FR - 603 - 89 Region 5 60 0.02, 0.02 0.02 5 IL 04 - FR - 001 - 89 Region 5 54 <0.01, <0.01 <0.01 6 NY 05 - FR - 004 - 89 Region 1 60 0.02, <0.01 0.015 7 AR 0S - FR - 208 - 89 Region 4 61 <0.01, 0.02 0.015Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 22 of 23 **Table I -**  **1. Residue data used to calculate tolerance for difenoconazole in/on wheat forage.**  Trial No. Trial Site

Trial ID Region PHI (days) Residues Found

(ppm) Average Residues

Used i n OECD MRL Calculations (ppm) 8 TX OS - FR - 208 - 89 Region 6 59 <0.01, <0.01 <0.01 9 AZ OW - FR - 504 - 89 Region 10 56 <0.01, <0.01 <0.01 1 0 KS MW - FR - 304 - 89 Region 5 61 <0.01, <0.01 <0.01 **MRID 44602001; Data previously reviewed by HED under PP#2F4107 (DP#s 248285 and 248419, 10/28/98,**  **S. Chun) .**  11 Caddo County, OK OS - FR - 101 - 95 Region 8 45 < 0.05, <0.05 <0.05 12 Wayne County, NC OS - FR - 601 - 95 Region 9 42 <0.05, <0.05 <0.05 13 Yellowstone County, MT OW - FR - 201 - 95 Region 9 52 <0.05, <0.05 <0.05 14 Paw

nee County, KS MW - FR - 301 - 95 Region 8 40 <0.05, <0.05 <0.05 15 Edwards County, KS MW - FR - 302 - 95 Region 8 42 <0.05, <0.05 <0.05 16 Weld County, CO MW - FR - 303 - 95 Region 8 42 0.074, 0.062 0.068 17 Ward County, ND MW - FR - 501 - 95 Region 7 35 <0.05, <0.05 <0.05 18 Corson County, SD MW - FR - 502 - 95 Region 7 34 <0.05, <0.05 <0.05 19 Jackson County, AR OS - FR - 101 - 96 Region 4 42 <0.05, 0.077 0.064 20 Caddo County, OK OS - FR - 750 - 96 Region 8 42 <0.05, <0.05 <0.05 21 Latah County, ID OW - FR - 601 - 96 Region 9 42 <0.05, <0.05 <0.05 22 Jackson County, MO MW - FR - 210 - 96 Region 5 42 <0.05, 0.061 0.056Difenoconazole Summary of Analytical Chemistry and Residue Data DP#: 38 4073

Page 23 of 23 **Table I -**  **1. Residue data used to calculate tolerance for difenoconazole in/on wheat forage.**  Trial No. Trial Site

Trial ID Region PHI (days) Residues Found

(ppm) Average Residues

Used i n OECD MRL Calculations (ppm) 23 Traverse County, MN MW - FR - 503 - 96 Region 5 36 <0.05, <0.05 <0.05 24 York County, NE MW - FR - 610 - 96 Region 5 42 <0.05, <0.05 <0.05 Figure I - 1. OECD tolerance spreadsheet summary of difenoconazole field trial data for wheat forage. **Difenoconazole Wheat Forage**  **Use Rate: 9.5 -**  **11 g ai/100 lb seed**

**PHI: 35**  **- 61 days**  **Total number of data (n)** 24 **Percentage of censored data** 75% **Number of non -**  **censored data** 6 **Lowest residue** 0.010 **Highest residue** 0.068 **Median residue** 0.050 **Mean** 0.036 **Standard deviation (SD)** 0.021 **Correction factor for censoring (CF)** 0.500 **Proposed MRL estimate**

**- Highest residue**  0.068

**- Mean + 4 SD**  0.120

**- CF x 3 Mean**  0.054 **Unrounded MRL** 0.120 **Rounded MRL 0.15**  High uncertainty of MRL estimate. [High level of censoring]