UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460 

## OC12 2 20\4

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Propoxycarbazone sodium (122019) 

### FROM:

THRU:

TO: Carl Chen, Plant Pathologist Biological Analysis Branch CynthiaDoucoure, Environmental Protection Specialist 

## (j·

## ~ Science Information and Analysis Branch Stephen Smearman, Economist

### -- "'J•._ 

# )w._ Economic Analysis Branch

### ~**u. ~**  Biological and Economic Analysis Division (7503P) Arnet Jones, Chief Biological Analysis Branch Diann Sims,

# Chief**~** Science Information and Analysis Branch TimothyKiely,Chief

# ~A~ Economic Analysis Branch '-....J Biological and Economic Analysis ivision ( 03 ) Wilhelmena Livingston, Chemical Review Manager Risk Management and Implementation Branch IV Pesticide Re-evaluation Division (7508P)


### ProductReview Panel date: October 8, 2014

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### SUMMARY Propoxycarbazone sodium, an herbicide that controls certainpost-emergent grasses and broadleafweeds in wheat, triticale, rangeland, and pastures was initially registered in June 2004. There are currently 6 active Section 3 registrations for propoxycarbazone sodium, including one technical. Based on available proprietary usage data, the predominant use ofpropoxycarbazone sodium is on winter wheat. The average annual pounds a.i. applied to winter wheat during the 2005-2012 period was 30,000, while the average annual pounds a.i. applied to spring wheat was 3,000. The available data shows that overall use ofpropoxycarbazone on winter wheat has decreased since 2005. For spring wheat, use ofpropoxycarbazone has remained relatively low. The average percent crop treated (PCT) for winter wheat is 5% while the PCT for spring wheat is <2.5%.


### INTRODUCTION The purpose ofthis document isto convey usage information and a broad overview ofthepest management roles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofpropoxycarbazone sodium, and eventually the general public. This document builds upon the dataBEAD provides in the Label Use Information System (LUIS) reports and the Screening Level Usage Analysis (SLUA) to Registration Reviewteams. The document is based on information and data available to BEAD as ofJuly 2014.


### HISTORY OFBEAD ASSESSMENTS FORPROPOXYCARBAZONE SODIUM BEAD prepared a Screening Level Usage Analysis (SLUA) for propoxycarbazone in July 2014 based on available data from 2004 to 2012 which showed that the primary use ofthis chemical in the U.S. is on winter wheat. Approximately 5 percent ofthe winter wheat crop is reportedly treated using an average annual amount of30,000 pounds a.i. Propoxycarbazone is used less on spring wheat. Less than 2.5 percent ofthe spring wheat is reportedly treated using an average annual amount of3,000 pounds a.i. Benefits Assessments- A search ofBEAD's Official Records data base for BEAD benefits assessments specifically for propoxycarbazone sodium did not find any records ofprior BEAD assessments specifically for this chemical inthe last 10 years. Emergency Exemptions- A search ofBEAD's Official Records did not find any Section 18s requests for propoxycarbazone sodium inthe last 10 years. Emergency exemptions may indicate that there is a need for a particular chemical that is notregistered for use on a particular site. An emergency exemptionrequest may yield information about a particular chemical's importance or value that is not found in other EPA records. However, a lack ofSection 18 assessments by BEAD does not specifically indicate the relative importance ofthe chemical.

Page 2 of9COMMON FORMULATIONS AND APPLICATION METHODS Propoxycarbazone sodium is formulated as a water dispersible granule and applied as a preplant, pre-emergence and postemergence application via ground or aerial application equipment.
USE SITES Agricultural Use Sites: Propoxycarbazone sodium is registered for use on wheat, triticale, rangeland, pastures, and Conservation Reserve Program. Non-Agricultural Use Sites: There are no non-agricultural use sites registered for propoxycarbazone sodium.
PROPOXYCARBAZONE SODIUM USAGE Agricultural Usage Trend Propoxycarbazone sodium is reportedly used on spring and winter wheat inthe U.S. Since 2005, overall use ofpropoxycarbazone sodium on winter wheat has declined overthe seven yearperiod (2005-2012), while use on spring wheat which accounts for approximately 10 percent ofthe total pounds ofpropoxycarbazone applied (Figure 1) has remained relatively steady but significantly lower compared to winterwheat as shown in Figure 1. In terms ofarea treated, the number of winter wheat acres has declined slightly overthe same seven yearperiod while the number of acres ofspring wheat has increased slightly as shown in Figure 2. When comparing the trend in the number ofacres treated to the number ofpounds applied, the continued use of propoxycarbazone indicates that growers ofboth spring and winter wheat still find benefits from using itto control various weed pests. Approximately 130,000 lb a.i. are applied annually on average to 5,609,000 acres at an overall application rate of0.023 lb a.i. per acre. The average a.i. rate ofapplication on winterwheat is slightly higher (0.026 lb a.i. peracre) than the overall average a.i. rate while the average a.i. rate ofapplication on spring wheat is lower (0.011 

### lb a.i. peracre) as shown in Table 1. The top states, in terms ofthe percentage ofthe total pounds a.i. applied, are Washington (26%), Kansas (24%), and Oklahoma (21%). Washington, Kansas and Oklahoma also have higherthan average a.i. application rates than other states as shownin Table 2.

Page 

### 3 of9Figure 1. Propoxycarbazone Sodium Usage: Pounds AI Applied, 2005-2012



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# ., c :I 0 1:1. 60,000

0 2005 2006

Source: Proprietary Data, 2005-2012 2007 2008 2009 2010 Year Wheat, Spring ...-wheat, Winter

Figure 2: Propoxycarbazone SodiumUsage: Total Area Treated, 2005-2012 2,000,000

0 2005 2006
. 2007 2008 2009 2010 Year Wheat, Spring ...-wheat, Winter Source: Proprietary Data, 2005-2012 Page 4 of9 2011

2011 2012

2012T bl 1 P a e b ropoxycar azone

# s d" 

# u o tum sage on Wh t 2005 2012 ea, 

## - Crops Proportion of Proportion of Avg AI. Rate Total Pounds AI. Total Area (lb a.i./acre) Applied Treated Wheat, spring 10% 20% 0.011 Wheat, winter 90% 80% 0.026 Source: Propnetary Data, 2005-2012
T bl 2 T St t fi U f P

a e op a es or se o b ropoxycar azone 

# s d" o tum, 2005 2012 

## - Top States Proportion of Proportion of Avg A.I. Rate Total Pounds AI. Total Area (lb a.i./acre) Applied Treated Washington 26% 20% 0.029 Kansas 24% 20% 0.028 Oklahoma 21% 18% 0.027 Montana 10% 11% 0.022 Oregon 7% 7% 0.024 Other* 0.2-5% 0
.5-12% 0.008-0.029 *Other states include CO, ID, NE, ND, SD, and TX.
Agricultural Use Intensity ofPropoxycarbazone Sodium Use inthe U.S. Another measure ofusage is the use intensity
. Inthis analysis, the use intensity is expressed as the average annual amount (in pounds) ofthe active ingredient applied per 1,000 acres ofcrop acres grown. This differs from the application rate, whichis expressed as the pounds a.i. applied pertreated area. Figure 3 spatiallyrepresents propoxycarbazone sodium's use intensity inthe U.S. inWashington, Kansas, Oregon, Oklahoma, and Montana show significant use intensity compared to other states where propoxycarbazone is used. Formore information onFigure 3, see Appendix A.

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### Figure3: Annual Average Agricultural Use Intensity ofPropoxycarbazone, 2008-2012

PoundsActive Ingredient per 1,000 Crop Acres Grown 

## D No Data 0 <0
.02 

## D o .o2

-o .1

- 0
.1

- 0
.25

. 0
.25

- 0
.5

- >0
.5 

### Source: ProprietaryData, 2008-2012

BIOLOGICALASPECTS RELEVANT TO PROPOXYCARBAZONE SODIUM Propoxycarbazone sodium belongs to the chemical family ofsulfonylaminocarbonyltriazolinone. Its site ofaction is to inhibit acetolactate synthase (ALS) classified by the Herbicide Resistance Action Committee (HRAC) and coded as HRAC Group B. It is listed by the Weed Science Society ofAmerica (WSSA) as a WSSA Group 2 herbicide. Ingeneral, the Group 2 or ALS inhibiting herbicides are associated withthe highest rank ofrisk on occurrence ofresistance (WSSA, 2010). Some genera composed ofweeds such as pigweed targeted by propoxycarbazone sodium are also associated withthe highest rank ofresistance risk (WSSA, 2010; Heap, 2010).

Page 6 of9ROLE OF PROPOXYCARBAZONE SODIUM IN PEST MANAGEMENT Propoxycarbazone sodium is an herbicide that can be appliedpreplant, preemergence, or postemergence, and was used mainly inpostemergence applications (Proprietary Data, 2011- 2012). Itis registered to control a number ofgrasses and broadleafweeds including cheat grass, downy brome,jointed goatgrass, pigweed, and wild oat ormustard in crops such as wheat and triticale. The major agricultural use ofpropoxycarbazone sodium is on wheat. Approximately five percent ofwinter wheat in the United States is treated withpropoxycarbazone sodium (SLUA, 2014). Inthe Pacific Northwest region, approximately 7.7% ofwinter wheat was treated in Washington during the period of2011-2012. The use in Oregon increased from approximately 6% in 2011 to 17% in 2012 ofwinter wheattreated (Proprietary data, 2011-2012). Section 2(ee) ofthe Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) allows that a pesticide may be mixed with anotherpesticide not prohibited bythe label to control a targetpest not specified onthe label ifthe application is to the crops specified onthe label. The single active ingredientproduct ofpropoxycarbazone sodium has received several Section 2(ee) recommendations for use in over 10 states such as CO, ID, KS, MT, MN, NE, ND, OK, OR, SD, WA, and WY. Ithas a supplemental label for a preplant/pre-emergence bum-down application tank-mixed with glyphosate in the fall for control or suppression ofBromus species in winter wheat (CDMS, 2014). Propoxycarbazone sodium is also co-formulated with mesosulfuronmethyl, both ofwhich are Group 2 herbicides, for postemergence control ofcertain grasses and broadleafweeds.
INFORMATION THAT MAY BEUSEFUL FORBEAD'S FUTURE WORK ON PROPOXYCARBAZONESODIUM The Agency currently does not have important information onpropoxycarbazone sodium. Obtaining the following usage information may improve future assessments conducted bythe Agency related to the use and importance ofpropoxycarbazone sodium:
• Propoxycarbazone sodium typical usage information (pounds a.i. applied, average applicationrate and average number ofapplications) for triticale, rangeland, pastures, and Conservation Reserve Program.

REFERENCES CDMS. 2014. Crop DataManagement Systems. Accessed August 2014. EPA, Propoxycarbazone sodium Screening Level Usage Analysis (SLUA), July 2014

Page 7 of9Heap, I. 2010. International Survey ofHerbicide Resistant Weeds. Online: http://www.weedscience.org. Accessed March 2014.

· Proprietary Data, 2005-2012

WSSA, 2014. Summary ofHerbicide Mechanism ofAction. Weed Science Society ofAmerica. Online: http:/ /wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf. Accessed March 2014.

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### APPENDIX A
The map included herein is primarily for the use ofthe risk assessors in the Environmental Fate and Effects Division. The map provides a verybroad geographical view ofthe average annual amount (in pounds) ofthe active ingredient applied per 1,000 acres ofcrop acres grown. These data are included in the maps because risk assessors are interested in the amount ofa pesticide used across agricultural land. The calculated values presented in the map are not equivalent to an application rate (lb ail A). The dataused to make these maps have several limitations. Any interpretationofthe maps should considerthe underlying data and the associated limitations carefully. The numerator (annual average pounds applied) is based onprivate market surveys ofpesticide use in agriculture averaged overthe last five years (Proprietary Data, 2008-2012). These surveys cover about 60 crops and are targeted in states that produce the majority ofthe crop. Although the surveys capture most ofthe use ofa particular active ingredient in agriculture, there are several limitations to these surveys.
• States with minorproduction ofa surveyed crop are not sampled • Not all types ofpesticides are surveyed inevery crop in every year • Many specialty crops with very small acreages are not included in the survey The result ofthese limitations is that states that show no usage may actually have a small amount ofthe active ingredient being used. In some cases the displayed use intensity may be distorted because the surveyed crops and the reported pesticide usage may not accurately represent the actual pesticide usage on the crops produced in the state. The denominator (1,000 crop acres grown) was also obtained from the same private market survey database. The "Crop Acres Grown" variable represents the total acres grown in a given state ofall ofthe surveyed crops. This value is independent ofpesticide usage and pesticide registration. It is important to note that the surveyed crops (about 60) are sampled from states that are major producers ofeach 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 state and/or crop was not included in the survey. Thereader should payparticular 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 likely be different.

• Page 

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