UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D.C

. 20460 

## OCT 0 62014

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Phenmedipham

FROM:

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_ Biological and Economic Analysis Division (75**~** TO: Miguel A. Zavala, Chemical Review Manager Risk Management and Implementation Branch III Pesticide Re-evaluation Division (7508P) PeerReview Panel date: September 10,2014 SUMMARY Phenmedipham was first registered inthe United States as an herbicide in 1970 (USEPA, 2005). A Reregistration Eligibility Decision (RED) was completed for phenmedipham in 2005. Based onprivate market usage data from 1998-2012, usage averaged approximately 120,000 pounds active ingredient (a.i.) applied annually on approximately 1.9 million acres treated. Theaverage a.i. rate overthis time period was 0.064 pounds a.i./acre. A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 that provides the percent crop treated for spinach and sugar beets. Forphenmedipham, during the SLUA timeframe of 2004-2012, usage for spinach averaged 3,000 lbs a.i. with an average 10 percent crop treated, and for sugar beets (the major use), usage averaged 80,000 lbs. a.i. with an average percent crop treated of45 percent. There are no non-agricultural uses ofphenmedipham. Phenmedipham is a postemergence herbicide that is used to control small seeded broadleaf weeds in spinach and sugarbeets. This herbicide is most often applied in combination with other broadleafand grass herbicides. Combinations with other herbicides provide for a broader spectrum ofweeds control. Given relative lowusage ofphenmedipham on spinach this herbicide may have limited utility for this crop. A major portion ofthe sugar beet crop is treated with this herbicide and it is likelythatthis herbicide is important for weed control in this crop. However, the number ofacres treated with this herbicide has declined since 2007, which may indicate that other herbicides are being used as alternatives.
INTRODUCTION The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pest management roles and quantitative usage information for phenmedipham. The BCP includes summaries ofprevious BEAD products and available public and/or private use and usage data for phenmedipham to describe the role ofthis chemical inpest management. Additional information onuse is available the Screening Level Usage Analysis (SLUA). Informationprovided in this BCP maybe used by stakeholders (e.g., users and registrants), OPP risk and benefit assessors, OPP risk managers, and the general public during the Registration Reviewprocess ofthis pesticide. Phenmedipham is a phenylcarbamate (Group 5) herbicide according to the Weed Science Society ofAmerica classification. Herbicides inthis group control weeds by inhibiting photosynthesis by blocking the fixation ofC02, which subsequently blocks the production ofthe energy products ofphotosynthesis (e.g. ATP) (Senseman, 2007).

USE SITES Agricultural Use Sites Phenmediphamregistered agricultural use sites include: beets and spinach Non-Agricultural Use Sites There are no registered non-agricultural use sites for phenmedipham.

Page2FORMULATIONS AND APPLICATIONMETHODS Phenmedipham is formulated as an emulsifiable concentrate and canbe applied as a broadcast or spray treatment with ground, aerial, or sprayer equipment. Foliar applications are made postemergence (to the plant)

..
HISTORY OF PHENMEDIPHAM and BEAD PRODUCTS Phenmedipham was first registered in the United States as an herbicide in 1970 (USEPA, 2005). A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 thatprovides the percent crop treated for spinach and sugarbeets (Table 4). A Reregistration Eligibility Decision (RED) was completed for phenmedipham in 2005. A search ofBEAD's Official Records database for BEAD benefits assessments specifically for phenmedipham did not find any records ofprior BEAD assessments specifically for this chemical in the last 10 years. A search ofBEAD's Official Records and the OPP Section_18 database did not find any Section 18 requests for phenmedipham in the last 10 years. Emergency exemptions may indicate that there is a need for a particular chemical that is not registered for use on a particular site. An emergency exemption requestmay yield information about a particular chemical's importance or value that is not found in other EPArecords. However, a lack ofSection 18 assessments by BEAD does not specifically indicate the relative importance ofthe chemical.

USAGE Agricultural Usage Based on private market usage data from 1998-2012, usage averaged approximately 120,000 pounds active ingredient (a.i.) applied annually on approximately 1.9 million acres treated. The average a.i. rate over this time period was 0.064 pounds a.i./acre. Figure 1presents phenmedipham usage in pounds a.i., and Figure 2 shows total areatreated in acres overthe 1998- 2012 timeframe (Proprietary Data, 1998-2012). Figures 1 and 2 showthat over this time period in terms ofpounds applied and acres treated !herehas been a sharp decrease in use from 2007 through 2012 while use had remained fairly steady from 1998 through 2007. Based onprivate market data for agronomic crops, phenmedipham is used to control broadleaf weeds in spinach and sugarbeetproduction (Proprietary Data, 2012). Neither ofthese crops competes well with weeds and as a result can suffer yield loss due to competition (Dexter, undated; Smith et al., 2009). Due to the relatively small size ofthese crops as well as theirbeing slow to shade the ground betweenthe planted rows, any weeds that are allowed to growwill ultimately out-compete these crops for needed resources. Phenmedipham is applied postemergence in both crops in orderto control broadleafweeds such as pigweeds, kochia, and lambs quarter (Proprietary Data, 2012). Because spinach and sugarbeets can be sensitive to this herbicide, applications are made only after the first four leaves ofthe crop plants have fully developed (Dexter, No Date Provided; Smith et al., 2009). Applications ofphenmedipham in Page 3spinach and sugar beets can be applied earlier, approximately two leafstage, ifthe applications are made using two applications each at a lower rate. (Dexter, undated; Smith et al., 2009). This herbicide is most often applied in combination with otherbroadleafand grass herbicides. Combinations with otherherbicides provide for a broader spectrum ofweeds control. Given that, on average, only 10% ofthe spinach crop is treated withphenmedipham, this herbicide may have limited utility for this crop. However, the fact that an average of45% ofthe sugar beet crop is treated withphenmedipham, it is apparent that this herbicide is important for weed control in this crop. The number ofacres treated withthis herbicide has declined since 2007, whichmay indicate that the overall need for this product may be declining (Figure 2). This may be, at least in part (ifnotprimarily), because ofthe dramatic uptake by growers ofgenetically modified sugar beettolerant to glyphosate, which now constitutes over 95% ofsugarbeet planting (e.g., Oeschger et al., 2011).

250,000

0


### FIGURE 1. 

### Phenmedipham Usage in Pounds Active Ingredient (1998-2012) Source: ProprietaryData, 1998-2012

3500000

0


### FIGURE 2. Phenmedipham TotalArea Treated in

### Acres**(1998~2012)** Source: Proprietary Data, 1998-2012 Page4Since the Reregistration Eligibility Decision (RED) was issued in 2005, the two periods below (1999-2005 and 2006-2012) were selected to show any change in use resulting from the RED. 

### Table 1. Comparison ofCropswith Highest Use ofPhenmedipham- Percent ofTotalLbs. Applied (1999-2005 and2006-2012) 1999-2005 2006-2012 Average annual= 170,000 lbs/yr Average annual= 61,000 lbs/yr 

### Crop %Lbs Crop %Lbs Sugar Beets 99% Sugar Beets 95%

Spinach 1% Spinach 5% Source: ProprietaryData, 1999-2012. Table 1 shows thatthe crop withthe mostpounds applied during boththe 1999-2005 and 2006- 2012 timeframes has been sugar beets accounting for approximately 95-99 percent oftotal pounds applied. The average annual usage inpounds has decreased approximately 64 percent from 170,000 lbs/year to approximately 61,000 lbs/year in the 2006-2012 timeframe. 

### Table 2. Comparison ofStates with Highest Use ofPhenmedipham- Percent ofTotalLbs. Applied (1999-2005 and 2006-2012) 1999-2005 2006-2012 Average annual= 170,000 lbs/yr Average annual= 61,000 lbs/yr



### State %Lbs State %Lbs Minnesota 33% Minnesota 45% North Dakota 22% North Dakota 14% Michigan 14% Michigan 14%

Idaho 14% Idaho 9% Other 17% Other 18% TOTAL 100% TOTAL 100% Other states in bothtime periods includes 12 additional states. Source: ProprietaryData, 1999-2012 As shown in Table 2, Minnesota, North Dakota, Michigan, and Idaho are the top states withthe highest use ofphenmedipham accounting for approximately 82 percent oftotal pounds applied in bothtimeframes, even though total pounds applied has dropped 64 percentbetween the two periods. Application Rates and Percent Crop Treated The average a.i. rate for the top crop (sugarbeets) interms ofpounds a.i. applied was 0.06lbs a.i./acre. The average a.i. rate for spinachthe only other registered use is 0.75 lbs a.i./acre as shown in Table 3.

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### T bl 3 Ph a e . enmed' h 

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### op rops: A

### verage AIR 

# .. ate, 2006 2012 

# - Annual Average AnnualAverage Avg. A.I. Rate (lbs Crop TotalAcres Pounds Treated* a.i./acres) Sugar Beets 57,000 956,000 0.06

Spinach 3,300 4,400 0.75 *Total Acres Treated sums all acres treated for a crop, mcludmg those acres that recetve multtple treatments. Source: ProprietaryData, 2006-2012 Forphenmedipham, during the timeframe of2004-2012, usage on spinach averaged 10 percent crop treated, andusage on sugar beets (the major use) averaged 45 percent crop treated. (See Table 4) Given that phenmedipham usage is declining as shownin Figures 1 and 2, the percent crop treated mightbe lower inrecent years thanthe averages over the 2004-2012 time frame. 

### T bl 4 Ph

a e . enmed' h 

### 1p1 am: p 

### t t t d, 2004-2012 

### ercen crop rea e Cro_p Percent Crop Treated Sugar Beets 45 Spinach 10 Source: BEAD, 2014 Geographic Distribution ofPhenmedip

_ ham Use Figure 3provides a very broad geographical view ofthe average annual amount (inpounds) of phenmedipham applied per 1,000 acres ofcrop acres grown. The calculated values presented in the map are not equivalent to an application rate (lb ai/ A), therefore, the map may show areas of high use intensity that do not correspond to the states listed in Table 2 since those are the states with the highest use ofphenmedipham based onpounds active ingredient applied. As shown in the map, Minnesota and NewJersey depict a high use intensity ofacres treated with phenmedipham. Please see Appendix I for a more detailed explanation ofthe information presented onthe map.

Page6Pounds Active Ingredient per 1,000 Crop Acres Grown 0 <0

. 1 0

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.2 0

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### FIGURE 3. AnnualAverage Agricultural Use Intensity ofPhenmedipham (2008-2012)

Non-Agricultural Usage There are no non-agricultural uses ofphenmedipham.

DATA. NEEDS The Agency currently does nothave complete informationfor phenmedipham. Obtaining the following informationmay improve future assessments conducted bythe Agencyrelated to the use and importance ofthis herbicide:

• Informationregarding any specific attributes ofthis herbicide in controlling weeds in either spinach or sugar beetproduction

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### REFERENCES BEAD. 2014. Phenmedipham Screening Level Usage Analysis. Biological and Economic Analysis Division, Office ofPesticide Programs, US Environmental Protection Agency. Dexter, A. (undated). Weed Control in sugarbeet. Available at: http://appliedweeds.cfans.umn

.edu/weedbull/Sugarbeet.pdf Accessed June 2014 Oeschger, T., Schweikhardt, D., and Thornsbury, S. 2011. Regulation ofglyphosate-resistant sugar beets: Challenges and uncertainty. Choices-Magazine ofFood, Farm and Resource Issues. 3rd Quarter 2011 26(3). http://www.choicesmagazine.org/choicesmagazine/submitted-articles/regulation•of-glyphosate-resistant-sugar-beets-challenges-anduncertainty Proprietary Data. 1998-2012. (pesticide agricultural usage data) Senseman, S.A. 2007. Herbicide Hand BookNinth Edition. Weed Sci. Soc. ofAm. 810 E. lOth Street, Lawrence, KS 66044-8897. U.S.A. Smith, R., S. Fennimore, and M. LeStrange. 2009. Spinach Integrated Weed Management. UC PestManagement Guidelines. Available at: http://www.ipm.ucdavis.edu/PMG/r732700111.html. Accessed June 2014. USEPA. 2005. Reregistration Eligibility Decision (RED) for Phenmedipham.

Page 8 -APPENDIX I The map included herein is primarily for the use ofthe risk assessors inthe Environmental Fate and Effects Division. The map provides a very broad geographical view ofthe average annual amount (in pounds) ofthe active ingredient applied per 1,000 acres ofcrop acres grown. These data are included inthe 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 data used to make these maps have several limitations. Any interpretation ofthe maps should consider the underlying data and the associated limitations carefully. · The numerator (annual average pounds applied) is based onprivate market surveys ofpesticide use in agriculture averaged over the last five years (Proprietary Data, 2008-2012)

. These surveys cover about 60 crops and are targeted in states thatproduce 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 in every crop in every year • Many specialty crops with very small acreages are not included in the survey The result of**th~se** limitations is that states that show no usage may actually have a small amount ofthe active ingredientbeing 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 onthe 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. Itis 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 notincluded in the survey. The reader should payparticular attention to the figure legends and realize thata 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.

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