UNI T ED STATES ENVIRONMENTAL PROTECTION AGEN CY WASHINGTON , D

. C

. 20460 

## DEC 

## 0 4 2 0

14

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION P REVENTION

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Penoxsulam (119031) 

### FROM: Sunil Ratnayake, Biologist 

# fl**~** L

# · Biological Analysis Branch 

# l**~ ~**  Sepehr Haddad, Environmental Protection Specialist 

# fiJ__... /""'**-~**

THRU: Science Information and Analysis Branch

## r~ Stephen Smearman, Economi st Economic Analysis B ran c h Bio logical and Economic Analysis Division (7503P) Arnet Jones , Chief Biological Analysis Branch ,":), Diann Sims, Chief Science Information and Analysis Branch Timothy Kiely, C hi ef 

## (/:+_.

# ~ Economic Analys i s Branch \) 

# J

_ Biological and Economic Analysts Division ( P) TO: Khue Nguyen, Chemica l Review Manager, RMIB III Pesticide Re-evaluation Division (7508P) 

### Peer Review Panel date: November 19,2014SUMMARY Penoxsulam was fi rst registered in the United States as an herbicide in 2004 (USEPA , 2004). This herbicide belongs to the triazolopyrimidine family of herbicides. It is applied as a postemergence treatment to control annual grasses , sedges, and broad leaf weeds in agricultural and non-agricultural use sites described below. Based on private market usage data from 2005-2012, usage averaged approximately 6,500 pounds active ingredient (a.i.) applied annually on approximately 207,000 acres treated. The average application rate over this time period was pounds 0.03 lbs 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 six crops (almonds, pecans , pistachios, plums, rice and walnuts). During the timeframe of 2004

- 2012, usage of penoxsu l am on rice averaged 6 , 000 lbs a.i. with an average 5 percent crop treated , and for almonds , usage averaged 1,000 lbs. a.i. w ith an average of 5 percent crop treated. For the remainder of the crops l isted in the SLUA (pecans , pistachios , plums , and walnuts) the average pounds a.i. was less than 500 lbs each over this timeframe.
INTRODUCTION The Biological and Economic Analysis Divi s ion (BEAD ) Chemical Profile (BCP) provides an overview of the pest management roles and quantitative usage information for penoxsulam. The BC P includes summari es of · previous BEAD products and available public and/or private use and usage data for penoxsulam to describe the role of this chemical in pe st management. Additional information on use is available the Screening Level Usage Analysis (SLUA). In formation provided in this BCP may be used by stakeholders (e.g. , users and registrants) , OPP risk and benefit assessors , OPP risk managers , and the general public during the Registration Review process of this pesticide. USE SITES Agricultural Use Sites Registered agricultural use sites of penoxsulam include: Fruit trees (non-bearing) , conifer seed orchards , nut trees, rice , and vineya rd s. Non-Agricultural Use Sites Registered non-agricultural use sites of penoxsulam include: ornamental lawns and turf , eucalyptus , non-crop areas , paved and unpaved areas, ponds , reservoirs, rights-of-way, sports arenas, and wetlands.

Page 2FORMULATIONS AND APPLICATION M ET HODS Penoxsulam i s formulated as a foliar s pray on dry-seeded rice crop s or as a foliar spray or granular formulation o n water-seeded rice crops . Th e granular formulation is only reco mmended for use on flooded rice paddies. It is al so formulated as so luble concentrate /liquid, and ready to use (RTU). Application methods inc lud e ground and aerial.
HISTORY O F PENOXSULAM and BEAD PRODUCTS Penoxsulam was first regis tered in the United States as an herbicide in 200 4 (USE PA , 2004). A Sc reening Leve l Usage Analysis (SL UA) was prepared by BEAD for this chemical i n 20 1 4 that pro vides the percent crop treated for six crops (almonds , pecans , pistachios, plums, rice and walnuts )
. For penoxsulam, during the SLUA timefrarne of2004-2012 , usage f or ri ce averaged 6 , 000 lb s a.i. with an ave rage 5 percent crop treated , and for almonds, u sage averaged 1 ,000 lbs. a.i. , a l so with an aver age perce nt crop tre ated of 5 percent. For the remainder of the crops listed in the SLUA (p ecans, pistachios, plums , and walnuts) the ave r age pound s a .i
. was less than 500 lb s each over this time frame. A search of B EAD ' s Offic ial Records did not find any BEA D bene fit s assessments over the last 10 years or emergency exe mption requests fo r p enoxsulam in the las t 8 years. Emergenc y exemptions may indicate that there is a need for a particular chemical that i s n ot registered for use on a particular site. An emergency exempti on request may yield informati on about a particular chemi ca l ' s importance or value that is not foun d in other EPA records. H owever , a lack of emergency exemptio n assessments by B EA D does not spec ific all y indicate th e relative imp ortance of the chemical. USAGE Agricultural Usage Based on private market usage data from 2005-20 1 2, us ag e averaged approximate ly 6,500 pounds act ive ingredi ent (a.i.) ap plied annually on approx ima tely 207 ,000 ac res treated. The average a.i. r ate ove r this time period was pounds 0.03 a.i ./ acre. F i gure 1 presents penoxsulam usage in pounds a .i. , and F ig ure 2 sh ows total area treated i n acres over the 2005

-20 12 timeframe (Proprietary Data, 2005

- 2012). Figures 1 and 2 s how that over this time period in terms of pounds appl ied and acres treated there has been an in crease in use f rom 2005 through 20 12, and especially between 2010 and 2011
.

Page 3

### FIGURE 1. 

### Penoxsulam Us age in Pounds Active Ingredient (2005-2012) 14,000

"0**~** 0.. a. <( ....:. .:i. VI "0 c**~** 0 a..

0 2005 2006 2007 2008 2009 2010 2011 201 2 Years So urce: Proprietary Data, 2005-2012


### FIGURE 2
. Penoxsulam Total Area T reated in Acres (2005-2012) 500000

VI Q)

.... u**~** "0 Q) 

# - ro Q)

.... 1- ro Q)

.... <( ro 

# - 0 1-
0 2005 2006 2007 2008 2009 2010 2011 2012 Years Source: P ropriet ary Data , 2005 -2012 Table 1 shows t hat th e crop with the most pound s applied during the 2008-2012 timeframe has been rice accounting for appro x imately 90 percent of total pounds app li e d
. The average annual usage in pounds during this timeframe h as b ee n approximately 8 , 600 lb s/year.

Pag e 4

### Table 1. 

### Crops with Highest Use ofPenoxsulam

- Percent of Total Lbs. Applied (2008- 2012) 2008

- 2012 Ave r age annual = 8 , 600 lbs/yr 

### Crop %Lbs Rice 89% Almond s 6%

Other* 5 % *Other crop s include wa lnuts, pecan s, and plum s Sou r ce : Proprietary Data, 2008-2012. As shown in Table 2 , between 2008 and 2012 , California was the top state with the highest use of pe noxsulam account ing fo r app roximately 70 percent of total pounds app li ed, followed by Louis · iana (15 percent ) and Arkansas (11 percent). 

### Table 2. States with Highest Use of Penoxsulam- Percent of Total Lbs. Applied (2008

- 2012) 2008-2012 Average annual 

### = 8 , 600 lbs/yr 

### State %Lbs California 68% Louisiana 15% Arkansas 1 1 %

Other* 6% TOTAL 100% * Other states include T ex as, Mi ss ouri , and New Me x ico Source: Proprietary Data , 2008-2012 Application Rates and Percent Crop Treated The average a.i. rate for the top crop (rice) in terms of pounds a.i. app lied was lbs 0.037 a .i./acre as shown in Table 

### 3
. Table 3. Penoxsulam U se on Top Crop (Rice): Average A
. I. Rate, 2008

- 2012 Annual Average Annual Average Avg. A
. I. Rate (lbs Crop Pounds Total Acres a. i./acres) Treated* Rice 8,600 231 , 000 0.037 *Total Acres Treated s um s all acres treated for a crop , mcludmg those acres that re ce ive multip l e treatments. Source: Proprietary Data, 2008-2012 Geographic Distribution of Penoxsulam Use Figure 3 provides a very broad geographi ca l view of the average annual amount (in pounds ) of penoxsulam applied per 1 , 000 acres of crop acres grown. The calculated values presented 

### in the map 

### are not equi valent to an applicat i on rate (lb 

### a.i ./ A), therefore , the map may show areas of high use intensity that do not necessarily correspond to the states listed in Tabl e 2 Page 5since those are the states with the highest use of penoxsulam based on pound s active ingredient applied. How e ver , in this case , the map does demonstrate that California and Louisiana which account for more than 70 percent of penoxsulam usage in terms of pounds a .i. applied are also the states with the highest use intensity because of application to rice fields. Please see Appendix A for a more detailed explanation of the information presented on the map . FIGURE 3. Annual Average Agricultural Use Intensity of Penoxsulam (2008-2012)

Pounds Active Ingredient per 1,000 Crop Acres Grown 

### :::::J < 0
.02 c::::J o. o2

- 0
. 10

. 0.11

- 0
. 25

- >0
. 25 0 N oDa ta

N on-Agricultural U s ag e Non

- agr i cultural data for penoxsulam is limited. The only availa ble national level data from public or private databas es show less than 

### 200 lbs a.i. used on turf and ornamental lawns in 

### 2011 (Proprietary Data , 

### 20 12).

Page 6BIOLOGICAL ASPECTS RELEVANT TO PENOXSULAM Penoxsulam belongs to the triazolopyrimidine family of herbicides. It is a systemic herbicide which provides a broad spectrum of weed control, including grasses, sedges , and broadleaf weeds. Similar to imidazolinone and sulfonylurea herbicide s, penoxsulam inhibits the activity of acetolactate synthetase (ALS) enzyme. Inhibiti on of this enzyme interferes with the production of bran ched chain amino acids (valine, leucine and isoleucine) in susceptible weed species
. Penoxsulam is absorbed by leaves, shoots , and roots. In jury symptoms can be observed 7 to 14 day s after foliar applications. Visual injury symptoms are inhibition of growth , chlorosis at growing points, and necrosis of terminal buds (Herbicide Handbook, 20 14).
ROLE OF PENOXSULAM IN PEST MANAGEMENT Penoxsulam is used for weed control in agricultural use sites such as rice , orchards, and vineyards. Penoxsulam is also applied on non-agricultural use sites as described previously. Peno xsu lam is a broad spectrum herbicide applied as a post-emergence treatment for weed control in rice production. Penoxsulam effectively controls weeds found in rice product ion such as ducksalad 

### (Heteranthera limosa) , rice flatsedge 

### (Cyperus iria) , barn yardgrass 

### (Echinochloa crus-galli), jointvetch 

### (Aeschynomene spp.) , and hemp sesbania 

### (Sesbania exaltata) (Uni versity of Arkansas, Undated). During the 2008 to 2012 timeframe , the hi ghest average annual usage (approximately 90 percent) , was in rice production (Table 1 ). During the same timeframe, the highest average annual usage (68 percent) was observed in California (T able 2). Use of penoxsulam is increasing significantly since the year 20 l 0 in the United States (Figures l and 2). Penoxsulam is used for the control of herbicide resistant biotypes of barnyardgrass in rice production (Talbert and Burgos, 2007). This may be a factor t hat contributed to the increased us e of penoxsulam
. Penoxsulam also applied for weed control on warm-season turfgrasses such as Bermuda grass 

### (Cynodon dact ylon), centipede grass 

### (Eremochloa ophiuroides), kikuyu grass 

### (Pennisetum clandestinum), St. Augustine grass 

### (Stenotaphrum secundatum), and zoys ia grass 

### (Zoys iajaponica) , (Turfcare Supply Corp., (Undated)). Furthermore , in F lorida, foliar or in-water applications of penoxsulam are made for the control of aquatic and invasive weeds such as hydrilla 

### (Hydrilla verticillata), water hyacinth 

### (Eichhornia crassipes), mosquito fern 

### (Az olla pinnata) , duck weed 

### (Spirodela spp.) , water meal 

### (Wolffia columbiana) and salvinia 

### (Salvinia spp.) (U niv. of Florida, 

### 2014). Penoxsulam is the only aquatic herbicide that can be applied to exposed sedimen t after drawdown to inhibit the regrowth of susceptibl e weeds (Masser et al. , 20 13).

Page 7In the United States , 46 weed species have developed resistance to ALS inhibiting herbicides (Heap , Undated (1)). Although penoxsulam is also an ALS inhibitor , only rice flatsedge ( Cy perus iria) has dev elop ed resistance to penox s ulam (Heap, Undate d (2)).
DATA NEEDS The Agency currently does not have complete i nformation for penoxsulam. Obtaining the foll owin g information may improve future assessments conducted by the Agency related to the use and importance of this herbicide: Data on non-a g usage such as turf and ornamental lawns in term s of pounds a.i. applied and application t imi ng and rates.
REFERENCES B EAD (Bio logical and Economic Analysis Division). 2014. Penoxsulam Screenin g Le vel Usage Analys i s. Biological and Economic Analysis Division , Office of Pesticide Programs, US Env ironmental Protection Agency. Heap , I. Undated (I ).The international Survey of Herbicide Resistant Weeds. Online Publication. 2014. Available at: www.weedscience.org. Access ed on Nov. 

### 6 , 2014. Heap , I. Undated (2). The International Survey of H erbicide Resistant Weeds. Weeds Resistant to the Herbicide Peno xs ulam
. Online Publication. Available at: http: //www. weedscience.org/summary/ ResistbyActive.aspx
. Accessed on Nov. 7 , 2014
. Masser, M.P., Murphy 

### T. R. , and J. L. Shelton. 20 1 3. Aq uatic Weed Management: Herbicide s. Southern Regional Aquaculture Center. Online Publication. Available at : http://www2.ca.uky.edu/wkrec / 36 1 aqplant.pdf. Accessed on Nov. 6, 2014
. Proprietary Da ta. 2005-2012. Propr ietar y Data
. 2012. Talbert , R.E. and N. R. Burgos. 2007. History and Management of Herbicide Resistant Barnyardgrass (Echinochloa Crus-galli) in Arkansas Rice. Weed Technology 21 (2):324-33 1
. Turf Care Supply Corp. Product Label. (Undated). Online Publication. Available at: http:/ / www.turfcaresupply.com/up l oad/documents/ label/900621.pdf. Accessed on Nov. 3, 20 1 4. University of Arkansas Research and Extension. (Undated). Arkansas Rice Production Handbook. Public ation Number MP 192. Onl ine Publication. Available at: http: //www.uacx.edu/publications/pdf / mp 192 / mp 192.pdf Accessed on Nov. 6 , 2014. Page 8University ofF 1 orida
. 2014
. Plant Management in Florida Waters: An Integrated Appr oach. Extension Center for Aquatic and Invasive Plants. Online Publication. Avai1 able at: http: //plants.ifas.ufl.edu/manage/deve 1 oping-management-p1ans/herbicideconsiderations/penoxsulam-considerations
. Accessed on Nov. 4, 20 1 4.
USEPA.2004
. EPA Fact Sheet for Penoxsu lam. Online Publication. Available at: http: //www .epa . gov/pesticides/ chem search/reg actions/registration/fs PC119031 27-Sep-04.pdf. Accessed on Nov. 7, 2014.

Page9APPENDIX A. The map included h ere in i s primarily for the use of the risk assessors in th e Env ironmental Fate and E ffects Divi s i on. The map pro vides a very broad geog raphi cal vi ew of the average a

nnual amount (in po und s) of the active in g r e di e nt applied per 1 , 000 acres of crop acres grown. These data are included in t he map s because risk assessors are interested in the amount of a pesticide used ac ross agricultural land. The calc ulated values presented in the map are not equivalent to an app li cat i o n r ate (lb a.i ./ A). The data used to make th ese maps have several limitations. Any interpretation of the maps sho uld consider th e u nderlying data and the associated limitations carefully. The numerator (annua l average pounds appli e d) i s base d on private market s urveys of pesticide use in agri culture averaged over the las t five years (Proprietary Data, 2 008-2012). These s urveys cover about 60 crops and are tar geted in s t a te s that produce the majority of the crop. A lthough the surveys capture most of the 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 sampled • Not all type s of pesticides are surveyed in every crop in every year • Many specialt y crops w i th very small acreages are no t include d in the s urv ey T he result of th ese lim itations is that states that 

### s h

9w no usage may actua ll y have a sm all amount of the active ingredient being used. In some cases the displayed use intensity may b e distorted because the s urveyed crops and the reported pestic ide usage may not accurate ly represent the actual pesticide usage on the crops produced 

### ill the sta te. T he d e nominator (1 ,000 crop acres grown) was also obtai ned from the same private market survey database. The "Crop Acres Grown" variab le represents the t otal acres grown in a g iv en state of all of th e surveyed crops. This value is independent of p estic id e usage and pesticide registration. It i s important to note that the surveyed crops (about 60) are sampled from states that are m ajor producers of each cro p. Therefore, there are cases where the actual crop ac reage in a sta te is higher t han that reported by crop acres grown in the s u rvey because either that sta te and/or crop was not included in the survey. The reader should pay particular attention t o the fig ure legends and reali ze that a map prepared for a particular chemical is not directly comparable to a map prepared for a different c h emica l as the leg e nd bins will likely be d iffere nt.

Page 10