UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASH IN GTON , D
. C

. 20460 

### MAR 11 2015

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: B EAD Chemica l Profi le (BCP) for Registration Review: Carboxin (090201) and Oxycarboxin (090202) FROM: Leonard Yourman, Ph .D. , Plant Path o logist 

# {t Biological Analysis Branch ·

THRU: Don Atwood , Ph.D., Entomologist

# $~~ ///'

# ?'~ Science Inf ormation and Analysis Branch Michele Ranville, Economi st ( 

# rrYf**~** Economic Analysis Branch 

## V**/~** Biological and Economic Analysis Division (7503P) Arnet J ones, Chief Biological Analysis Branc Diann Sims , Chief Science Information
. an Analysis Branch Timothy Kiely, Chief

# ~ vA-

# \~ Economic Analysis Branch Biological and Economic Anal s Di v ision 3P) TO: Dana Friedman , Chemical Review Manager RMIB 2 Pesticide Re -evaluation Division (7508P)
Product Review Panel date: December 17 , 2014

Page 1SUMMARY Ca rboxin and oxy carbox in were first reg i ste red in the U.S
. in 1968 and 1971 , respect ively. B oth fungicides are m ember s of the oxathiin-carbo xi mide class of systemi c f un g ic ide s . They are class ified by th e Fun g icide Re s is tance Action Co mmittee as Group 7 s uc c inate deh ydrogenase inhibitors (SDHI). Carboxin and oxycarboxin were the first gen eration of SDHI fungicide s, fo ll owed several yea r s l ater by broader spectrum SDHI fungicides such as boscalid and fluopyram, among others (A venot and Michailides , 20 1 0)
. Agricultural use is limited to carboxin as a seed treatment. The major agricu ltural use sites for ca r box in are seed treatme nts of whea t (sprin g and w inter), peanuts , soybean , and cotton. According to avai l able proprietary informat ion, the major usage of carboxin in te rms ofboth to tal pounds appli ed and total acres treated i s on winter wheat seed
. Non -agricultural u se sites for both carbo xin and oxycar boxin include orname ntal s. However, oxycarboxin use (target in g rust pathogens) is limited to foliar application to ornamental s in enclo sed commercial struct ure s su ch as greenh ouses, shadeho uses , and interiorscapes.
INT RODUCTION The Bio logical and Eco nomic Analysis Divi sion (BEAD) C hemical Profile (BCP) provides an overv iew of the pest management roles and qu antitative usage information fo r carboxin and oxycarboxin. The BCP includes summaries of previous BEAD products and available public and/or pri vate use and usage data for carbox in and oxycarboxin to describe the role of this c hemical in pest management. Additional information on use is ava il ab le in the Carboxin Label Data Report and the Oxycarboxi n Label Data Report provided in the publ ic docket for this chemical. Informati on provided in thi s B EAD Chemical Profile ( B CP) may be used b y stakeholders (e.g. , users and registrants), OPP risk assessors and risk managers, and the general public during the Registration Review proce ss of this pest ic ide.
AGRICULTURAL USE SITES Carboxin is registered as a seed treatment of barley , beans, canolalrape , corn (field , p op , and sweet), cotton, grasses grown for seed, mustard , oats , onion, peas, rice, rye , safflower , sorghum , soybeans, triticale , and wheat. Oxycarboxin is not r eg istered for agricultural use.
NON-AGRICULTURAL USE SITES O rnamental s are the only non-agricultural use s ites for which carboxin dip application is labeled in some locat i ons. Oxycarbox in is onl y registered for foliar applicati on on ornamenta l s grown in enc lose d commercial structures such as greenhouses , s hadehouses, and interiorscapes. Page 2

### FORMULATIONS AND APPLICATION METHODS Carboxin i s formulated for seed or dip treatment as a flowable conce ntrate, emu l sifiab le concentrate , dust, and ready-to-use product. Car bo xin i s applied as either a seed or dip treatment both by commercial seed treaters and on - farm appl icators. Depending upon the formulation , application equipment may include cup , dip tank, mist-type seed treater, slurry-type seed treater, hopper box , and planter /see d box. Ox ycarbox in is formulated as a wettable powder and may only be applied as foliar application by commercial applicators utilizing hand held equipment.


### HISTORY OF CARBOXIN/OXYCARBOXIN AND BEAD PRODUCTS Carboxin was first registered for use in the 

### U.S. in 1968 (EPA 2004). Oxycarboxin was registered for use in 1971. A Reregistration Elig ibility Deci sio n (RED) was issued for carboxin in 2004. An addendum to the RED for oxycarboxin was issued in 2005. The carboxin RED required additional label language to avoid environmental hazards and occupational exposure. A search of BEAD's Official Records and the OPP Section 18 database did not find any Section 18 requests or benefits assessments for carboxin or oxycarboxin in the last 10 years. Emergency exemptions may indicate that there is a need for a particular ch emica l that is not registered for use on a particular site. An emergency exemption reque st may yie ld information about a particular che mical's importance or value that is not found in other EPA records. · However , a lack of Section 18 asse ssments by BEAD does not specifically indicate the relative importance of the chemical.


### CARBOXIN USAGE Agricultural Usage Usage of carboxin in terms of number of acres treated and totallbs applied was minor from 2006-2008 (Figure 1). In 2009, carboxin usage s howed an apparent increase which remained re l atively constant through 20 1 1. The increase during this time frame is likely related to increased use on soybeans and new usage on wheat. From 20 11 to 2012, there was a reduction in carboxin usage resultin g from decreased usage on both soybeans and winter wheat. Figure 1 shows a sharp increased usage from 2008 to 2009 and a decreased usage from 2011 to 20 12. This may be due at least in part to its scale. The crops listed in Tab le 1 are planted on a total o f well over one hundred million acres per year (fluctuating by millions of acres per ye ar). Considering the fluctuation of p l antings of these major crops and the low range of percent crop treated (e.g. , soy bean: < 1 to < 2.5 PCT) (Table 2), the change of usage on seed that might be planted on approximately 1 million acres out of more than 100 million acres for these crops Page 3would appear in line with the PCT ranges and may explain the large increase and decrease in usage between 2008 and 20 12.

-o "' Ql Ql
.... ._ IV

... Ql <t ... 1- 1400000

0 Historical Carboxin Us age



# ........ 

# ,_.•----· 2006 2007 2008 2009 Year 2010 2011

Sum ofTotal Area Treated - •- Sum of Pounds AI Figure 1. National Carboxin Agricultural Usage from 2006 to 2012. Source: Proprietary Data , 2006-2012 60000

0 2012

A review oftotal carboxin usage from 2009-2012 indicates that the primary use site is wheat , accounting for approximately 56% of both totallbs applied and 66% of total acres treated (Table 1

). Carboxin average app li cation rates range from 0.010 to 0.89 lbs a. i./acre for the major use sites in the United States with lowest application rate on cotton and the highest application rate on peanuts. H owever , while wheat has the high est percentage of lbs applied and total acres treated, the cr op with the highest percent crop treated is peanuts with an average of 5% c rop treated and a maximum of 10% crop treated (Tab le 2).

Page4Table 1. Crops with Highest Use ofCarboxin (2009 -2012). Crop Lbs A.I. %of Total Total Ac r es % ofTota l Avg. A.l. Rate App li ed Carboxin Treated* Carboxin Lbs Applied Treated Acres (lbs a .i./acres) W inter Wheat 78 ,424 4 6 2 ,200,158 54 0.036 Soybean 53 ,3 23 31 1 , 089 , 933 27 0.049 Peanuts 21 , 060 12 236 , 635 6 0.089 Spring Wheat 17 , 285 10 475 ,4 88 1 2 0.036 Cotton 514 0 52 , 584 1 0.0 1 0 *Total Acres T reated s um s all acres treated for a crop , m c ludmg those acres that rece1v e mult1ple treatments. Source: Proprietary Data , 2009

- 2012 

### T bl 2 P

a e . ercent 

### C T rop d
. hC b
. reate Wit ar oxm. Crop Percent Crop Treated Average Maximum Winter Wheat <2.5 <2
. 5 Soybean < 1 <2.5 Peanuts 5 1 0 Spring Wheat < 2.5 <2.5 Cotton <1 <2.5 So urce: BEAD 2014 SLUA
Table 3 indicates states with highest usage o f carboxi n in terms of lbs a.i. applie d and acres treated. Loui siana and Georgia are the states wi th highest car boxin u s age in terms of total lbs of carboxin applied ( 1 3%). The six states in Table 3 w ith most lbs applied represe nt 60% of total lbs applied and are the only states which e x ceed 5% of total carboxin lb s applied. Washington, Louisiana, and Texas are the states with the hi ghest percent of total acres treated at 11%. The se states with most usage acco unt for 57% of total ac re s treated w ith carboxin with no ot her state exceedin g 6% of acres treated
. Highes t app li cation rate, 0
. 062 lbs a.i./acre , i s used in Georgia and lowest application rate is in T e xas , 0.035 lbs a.i./acre.
Table 3. States with Hi g hest U se of Carboxin (2009-20 12)
. State Total Lbs %of Total Total %of Total Applied Carboxin Acres Acres Treated Avg. A.I
. Rate Lbs Applied Treated* witb (lbs a.i./acres) Carboxin* Louisiana 22,598 1 3 438 , 500 11 0.052

Geo r gia 22 , 092 13 372,200 9 0.062 Washington 17 , 033 10 453,600 11 0
. 038 Texas 15 , 068 

### 9 427 , 800 11 0.035 Mississippi 14 ,3 19 8 294 , 100 7 0.051 Oklahoma 1 1 , 525 7 3 11 ,6 00 8 0.037 *Total Acres Treated s um s all acres treate d , mcludmg those acres that rece1ve multtpl e treatments. So urce: Proprietary Data, 2009-2012 Page 5Geog raphic Distribut ion of Car boxin Use Carbox in has wide u sage in the United States (Figure 2) w it h th e exception of New England and Southwest ern United States. States with highest pounds per 1 ,000 crop acres grown include Washington, Louis i ana , Georgia, and Mississippi and primari ly reflect use on winter wheat , soybeans, p eanuts , and soybeans, respectively.

Pounds Active Ingredient per 1 , 000 Crop Acres Grown 0 NoData 

## D < o . o3 CJ o .o3

- 0
. 1 O o . 1-0
.3 .0
. 3-0
. 6 ->0
.6 Figure 2. Annual average agricultural use intensity of carboxin (2008

- 20 12).
Non -Agricultural Usage No estimate of non-agricultural usage of carboxin on o rnam ental s is avai l able from proprietary data sources. Special Local Need 24C labels are in effect for carboxin-containing products in O regon for treating g rass seed for export only.

P age 6OXYCARBOXIN USAGE Agricultural Usage There is no agricultural usage for oxycarboxin. Non - Agricultural Usage Non-agricultural usage data for oxycarboxin are not available.
BIOLOGICAL ASPECTS RELEVANT TO CARBOXIN AND OXYCARBOXIN Carboxin and oxycarboxin are classified by the Fungicide Re sis tance Action Committee as Group 7 succinate dehydrogenase inhibi tors (SDHI). Carboxin and oxycarboxin were the first generation of SDHI fungicides, followed severa l years later by broader spectrum SD HI fungicides suc h as boscalid and fluopyram among others (Avenot and Michai lides, 20 10)
. SDHI fung icide s interrupt respiration by blocking electron transport in the mitochondria. The systemic characteristic of carboxin and oxycarboxin make them valuable where required for controlling seed-borne and seedling diseases, primarily basidiomycete pathogens, such as rusts, smuts, and bunts (Ulrich and Mathre, 1972). Oxycarboxin i s lab eled for use to manage ru st diseases on ornamental plants grown in enclosed structures.
ROLE OF CARBOXIN AND OXYCARBOXIN IN PEST MANAGEMENT The first ge neration SDHI fungicide carboxin is generally effective as a seed treatment against seed and seedling diseases caused by basidiomycete fungi, s uch as loose smut, common bunt of wheat, covered smut , scab seedling blight, flag smut, as well as some seed lin g diseases such as Rhizoctonia root rots of soybean (e.g., McKay et al., 2011; Schu ltz and French, 2011 ). Carboxin Until the registration of carboxin as a seed treatment winter wheat was susceptible to new races of smut fungi (Crop Profiles for Winter Wheat in Oregon , 1999). Eastern Oregon winter wheat seed was nearly all treated with fungicide. Until 1995, the seed treatment of choice was carboxin alone or mixed with other fungicides and/or insecticides. Since the mid

- 1990s, other seed treatment fungicides have been available, some of whic h have been more effective than carboxin (Crop Profi les for Winter Wheat in Oregon, 1999). For wheat g rain production, in determining if there is a value from treating seed the grower must balance the cost of seed treatment with the return (Dewolf , 2013; Byamuka ma and Fanning , 20 14; Paul , 20 11 ). Where there is no prior history of seed-borne diseases (such as smuts and bunts) in the field, the value of a fungicide seed treatment may be minimal, especially in good planting weather. Seed treatment for loose smut where it ha s been observed requires a systemic fungicide, including carboxin, tebuconazole, and difenoconazo le. However, extension specialists Page 7recommend that wheat kept for seed the next season be treated with fungicide(s). Fungicide treatments may help seed with low germination rates (less than 90%) improve stand esta blishment (DeWolf, 2013). Where wet soils are encountered durin g planting fungicide seed treatments have been recommended (e.g. , Bosley, 2009; Paul, 20011; Byamukama and Fanning, 20 14). For wheat seed used for seed production systemic treatments such as carboxin and others , fungicides are recommended (Dewold , 2013) to reduce the likelihood of smuts and bunts being introduced into stocks. Because of the value of seed stock, treatment i s usually considered economically justifiable. Damping off and seedling rots, including Rhizoctonia, can be problem seedlin g diseases of soy bean. Carboxin is one of severa l seed treatments avai l able (e.g., Giesler and Ziems, 2008 ; Osborne and Ruden , 20 11 ). As with the case in wheat, soybean seed treatments are indicated when conditions indicate that seedling diseases may be a problem either due to past experience in the field or because of impending weather causing cool wet soils at planting. Seed treatments are also advised when planting seeds of margina l quality (e.g., Koenning et al. , 2000). It was estimated that 60-70% of the 20 14 soybean seed planted was treated with fungicides , compared with 30% in 2008 and 8% in 1996 (USB, 2014). All commercial cotton seed is treated with fungic ide s . Typically systemic fung icides such as carboxin are combined with protectant fungicides s uch as captan for greater see d protection (e.g. , Koenning, undated). Commo n cotton seedling diseases that fungicide seed treatments target are Pythium, Rhizoctoni a, and Fusarium rots (Wrather and Sweets, 2009; Padgett et al. , 2002). All commercial peanut seed is treated with fungicides. Several multi-a.i. products are used as peanut seed treatment , including those with carboxin. Treated seed generally provide improved germination , seedling rot inhibition, and can help prevent field-contamination of Cylindrocladium para siticu m (e.g., Spears et al , 2002)
. Carboxin may be used as a seed treatment and is typically mixed with other fungicides (OSU, 2012). Other fu ngici des may be app li ed in-furrow at planting. Three 24C SLN labels are currently in effect for carboxin to treat grass seed for export to control seedling diseases such as damping-off, Pythium damping-off , Rhizoctonia rots (WSU, 2014). According to the Oregon Seed Association (Perkowski, 2013): "The value and volume of ryegrass seed exports surged in 2011 , stayed strong in 2012, and saw a healthy uptick during the first quarter of 2013
... Higher sales in early 2013 likely represented the tail end of the upswing in exports ... The dimming prospects for exports are largely due to the market outlook in Europe , a major buyer of perennial rye grass seed for turf. Unseasonably low temp erat ures and adverse weather in Europe have hampered demand for perennial ryegrass seed
. .. "

Page 8Oxycarboxin Several fungicides are availab le for managing rust diseases on ornamentals in enclosed structures such as greenhouses (UMass , undated). These include myclobutanil , fludioxonil , fluoxastrobin, fluto lanil , chlorothalonil , and azoxystrobin. BEAD did not extensively evalua te the relative efficacy of reg i stered a.i.s , although one early efficacy study found that oxycarboxin generally was eff ect i ve (along with myclobutanil) for managing carnation rust i n California greenhouses (Ferrin and Rohde , 1991 ).
D ATA NEED S The Agency current ly does not have important i nformation on carboxin and oxycarboxin
. Obtaining the following information for all regi s tered non - agricultural sites may improve future assessments conducted by the Agency related to the use and importance of carboxin and oxycarboxin: Usage • Total pounds acti ve ingredient applied • Percent crop/ site treated
. • Application rates : typical and maximum • Fr equency of app lication • App li ca t ion Intervals • Methods of application • Targe t or niche pests • Efficacy information/product p erformance

RE FE RE N C E S Avenot , H. F
. and Michai lides , T. J. 2010. Progress in understanding molecular mechanisms and evolution ofresistance to succinate hehydrogenase inhibiting (SDHI) fungicides in phytopathogenic fungi. Crop Protection 29:643

- 651. BEAD
. 2014. Screeni ng Level Usage Analys i s (SLUA) for Carboxin
. Bosley , D. B. 2009. Wet year may mean fungus i n wheat harvest , seed crop s . Fort M organ (Colorado) Times , Aug. 27 , 2009. http: //www.fortmorgantimes.com/fort-morganagriculture/ ci 13217356 Byamukama, E
. and Fanning , B
. 2014. South Dakota wheat: Planning fungicide seed treatments . Agfax.com. http 

### : I I

agfax.com/20 14 /08/ 22/ south

- dako t a-wheat

- planning- fungicide-seed



### treatments/ Page 9Crop Profiles for Win ter Wheat in Oregon. 1 999
. http: //www .ipmcenters.org/ cropprofiles/ docs/ orwheat. pdf DeWo lf, E. 2013. Fungicide seed treatments for wheat. No-Till Farmer. Oct. 7 , 2013
. http: //www .no - tillfarmer.com/pag e s/News--- Fungicide-Seed

- Treatments-For- Wheat.php EPA. 2004. Carboxi n Fact Sheet. http: //www. e pa. govI oppsrrd 1 / REDs/factsheets/00 l2fact carboxin.pdf Ferrin, D. M. and Rohde, R. G. 1 991. Tests com p are fung i c i des for control of rust on greenhouse carnations
. California Ag riculture 45:16

- 17. htt p: // ucanr.edu/re posi toryfiles/ca4504p 1 6

- 69551.pdf Gies ler, L. J. and Ziems, A. D. 2008. Seed treatm ent fung i cides for soybeans. University of Nebraska Extension. http: //ianrpubs
. unl.edu/pages/publicationD.jsp?pub li cationld= 1 007 Koenning , S., Ferguson, 

### J. and Dunphy , E. 

### J. 2000. Soybean seed and seedling diseases. North Carolina S tate Un i ve r sity Extension. http: //www .ces.ncsu.edu / depts/pp/notes/S oybean/soy002/s o y 002.htm Koenning , S. Undated. Cotton seedling diseases. North Caro li na Sta te Uni versity Ex tension. http: //www. ces. ncsu.edu/ depts/pp / notes/C otton/ cdin 1Icdi n l .htm McKay, A H. , Hagerty , G. C., F o ll as, G
. B. , Moore, M
. S., Christie, M.S., and Beresford, R. M. 2011. Succinate dehydrogenase inhibitor (SDH I) fu n gicide res i stance prevention strategy. New Zealand P lant Protection 64:119

- 124. http: //nzpps.org/journal/64/ nzpp 641190.pdf Osborne , L. and Ruden, K. 20 1 1
. Seed treatment f u ngicide options for soybeans in South Dakota. S outh Dakota State University Extension Pub l. FS966. http: / /pu bstorage. sdstate.edu/ AgBio P ub li cations/articles/FS966.pdf OSU. 20 1 2. Peanut disease contro l guide li nes. Okl ahoma S tate Uni versity Extension. http ://entop lp.okstate.edu /profi l es/j d/20 12%20Peanut%20Disease%20Control.pdf Padgett, B., Colyer, P. , Burris, E. and Whitam, K. 2002. Hopper box app lied fungicides for man agement of cotton seedli ng diseases
. http://www.lsuagcenter.com/en/communications/publications/agmag/Archive/2002/Wi nter/Hopp er

+ Box +Applied+Fungicides + for+Management+of +C otton+ Seedling+Diseases. h tm Paul , P. 2011. Wi nter wheat seed needs f ungicide seed treatment. Prairie Star, Oct. 8, 2011. htt p: //www. theprairiestar.com/news/ crop /winter

- wheat

- seed

- needs

- fu n gicide-seedt reat ment / article f13a3096

- fl b6

- 1 1 e0

- b175

- 00lcc4c002eO.html Perkowski , M. 2013. Ex perts say ryegrass see d exports have likely peaked. Oregon Seed Association. http: //www . .oregonseed.org/experts-say-ryegrass-seed-exports-have-likely-peaked/
Page 10Proprietary Data. 2006-2012. Proprietary Data. 2008-2012 Proprie tary Data. 2012 Schultz, D. and French , R. D
. 2011. Fungicide seed treatment decisions for use on winter wheat. Texas A&M University Extension. http: //amarillo.tamu.edu/files/ 20 1 0111 /WheatFungSeedTrtPLPA WhtSdO 11-1.pdf Spears, J. F
. , Jordan , D. L. , and Bailey , J. E. 2002. Peanut seed production: A guide for producers of Virginia-type peanut seed. North Ca rolina State University Extension Publ. AG622. http: //www.peanut.ncsu.edu/PDFFiles/004968 /Peanu t Seed Production Guide.p df U lrich, J. T. and Mathre , D. E. 1972. Mode of action of oxathiin systemic fungicides. Journal of Bacteriology , 110:628-632. http: //www.ncb i.nlm .nih.gov / pmc / articles/PMC247458/ pdf /jbacter00361-0 188.pdf UMass. Undated. Rusts

- Fungicides. University of Massachusetts Ex tension. (accessed 1 2/2/2 0 14). http: / I greenhousediseaseguide.

### urn ass. edu/rusts2 USB. 20 1 4. Six things fa rm ers should now about seed treatments. United Soybean Board, Feb. 20, 2014. http: / / unitedsoybean.o r g/art icl e/s i x -things-farmers

- shou l d-know-about-seed

treatments/ Wrather , A. and Sweets , L. 2009. Cotton seedling diseases: Answers to frequently asked questions. U niv erity of Missouri Extension Publ. MP734. http: //extension.missouri.edu / explorepdf/miscpubs/mp0734.pdf WSU
. 20 1 4
. Washington and Oregon SLNs. (accessed 12/2/2014). http://pico l s ln .wsu.edu/s ln Disp lay.aspx?state = OR

Page 11APPENDIX A The map included herein is primarily for the use of the risk assessors in the Environmental Fate and Effec ts Division. The map provides a very broad geographical view of the average annual amount (in pounds) of the active ingredient applied per 1 , 000 acres of crop acres grown. These data are included in the maps becau se risk assessors are interested in the amount of a pest icide used across agricultural land. The calculated values presented in the map are no t equivalent to an application rate (lb ai/ A). The data used to make these maps have several limitation s. Any interpretation of the maps should consider the underlying data and th e associated limita tions carefully. The numerator (annual average pounds applied) is based on private market surveys of pesticide use in agriculture averaged over the last five year s (Proprietary D ata, 2008-2012). These survey s cover about 60 crops and are targeted in state s that produce the majori ty of the crop . Alt hough the s urveys**capt~re** most of th e use of a particular active ingredient in agriculture, there are several limitations to these surveys.
• States with minor production of a surveyed crop are not sa mpl ed • No t all types of pesticides are surveyed in every crop in every year • Many specialty crops with very small acreages are not included in the survey The r esult of th ese limitations is that states that show no usage may actually have a small amount of the active ingredient being used. In some cases the displayed use intensity may be d is torted beca use the s urveyed crops and the reported pesticide u sage may not accurately repre sent the actual pesticide u sage on th e crops produced in the state. The denominator (1 , 000 crop acres grown) was also obtained from the same private mar ket survey database. T h e "Crop Acres Grown" variable represents the total acres grown in a given state of all of the s urveyed crops. This value is indep ende nt of pesticide usage and pesticide registration
. It is important to note that the surve ye d crops (about 60) are sa mpled from states that are major producers of each crop. Therefore, there are cases where the actual crop acreage in a state is higher than that reported by crop acres grown in the survey because either that sta te and/or crop was not included in the survey. The reader s hou ld pay particular attention to the figure legends and realize that a map prepared for a particular chemical is not directly comparable to a map prepared for a different chemical as the legend bins will lik e ly b e diff erent.

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