UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C

. 20460 

## JUNO 42015 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION
MEMORANDUM

SUBJECT: FROM:

THRU:

TO: 

### Sulfentrazone Qualitative Benefits Assessment (PC# 129081). Bill Chism, Ph.D., Senior Biologist Biological Analysis Branch Elizabeth Hill, M.S., Economist Economic Analysis Branch 

### /.?-#/**~** 

# "'J3e-P**~** 

# -

Biological and Economic Anal sis Division (7503P) Arnet Jones, Chief Biological Analysis Branc Timothy Kiely, Chief

# ~**~** Economic Analysis Branch )· ' Biological and Economic Analysis 1 • 

### ision (75 Christina Scheltema, Chemical Review Manager Neil Anderson, Chief RiskManagement and Implementation BranchIII Pesticide Re-evaluation Division (7505P) BEAD Product Review Panel date: 

### May 6, 2015

### SUMMARY Sulfentrazone is undergoingregistrationreviewby the Pesticide Reevaluation Division (PRD). The Biological and Economic Analysis Division (BEAD) conducted a qualitative assessment of the benefits ofsulfentrazone. Sulfentrazone is registered on field crops, fruits, ornamentals, turfgrass, andvegetable crops. This qualitative assessmentreviews five example crops to demonstrate that sulfentrazone is an affordable and effective tool for the control ofherbicide resistant and difficultto control weeds in com, dry beans/peas, soybeans, sunflower, and tobacco. 

### BACKGROUND The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) authorizes EPAto register pesticides under 40 Code ofFederal Regulations (CFR) Part 158. FiFRArequires the EPAto regulate the use ofa pesticide to the extentnecessaryto preventunreasonable adverse effects on the environment, including humanhealth, where 'unreasonable' is defined as taking into account the economic, social, and environmental costs and benefits ofthe use ofthe pesticide. The primaryrisk concern for sulfentrazone is riskto non-targetplants, primarily from spray drift. The riskthresholds for chronic effects to birds and estuarine/marine invertebrates are also exceeded. Furthermore, the Agencyhas significantuncertainty in the risk estimate for estuarine/marine invertebrates. The Agency has a risk concern for any workers who handle sulfentrazone without wearing chemical-resistant gloves; however, most sulfentrazone product labels require use ofgloves (EPA, 2015b ). Sulfentrazone is a broad spectrum, selective herbicide which canbe applied eitherpreplant incorporated orpreemergence for the control ofbroadleaf, grass and sedge weeds. Itis used on field crops, fruits, ornamentals, turf grass, and vegetable crops in many states. Sulfentrazone is a ProtoPorphyrinogen Oxidase (PPO) Inhibitor (WSSA Group 14). This herbicide inhibits the protoporphyrinogen oxidase enzyme which is importantinthe production ofchlorophyll which causes a peroxidation oflipidsinthe cell membrane, leading to cell leakage (WSSA, 2014). PPO herbicides provide growers the option ofusing an additional mechanism ofaction for herbicide resistant weeds. For agricultural uses, sulfentrazone is generally soil directed using ground equipment, with low booms and larger droplet sizes. Aerial applications account for 2% ofthe total soybean acres· and 5% ofthe total sunflower acres treated with sulfentrazone. Aerial treatments occurwhen fields are too wet for ground equipment and whentreating large acreage fields. 

### QUALITATIVE BENEFITS Sulfentrazone is used on alfalfa, asparagus, barley, beans (green), beans (lima), cabbage, com, cucumber, dry beans/peas, fallow, peanuts, peas (green), potatoes, rice, soybeans, strawberries, sugarcane, sunflowers, tomatoes, tobacco, watermelons, and wheat (Chism et. al., 2015). In

Page2selecting crops for this analysis, percent crop treated and average total acres treated were considered. Reviewed crops include com, dry beans/peas, soybeans, sunflowers, andtobacco. Table 1. Screening Level Usage Analysis (SLUA) Estimates ofAgricultural Uses of Sulfentrazone. Maximum Average Average Single Annual Total Average Crop Application Rate Application Acres Percent Crop (lb ai/acre) Treated

.. ,

### .. (2008-2012) From Label Treated (2004-2013) Ob ai/acre) (2008-2012) Asparagus 0.19 0.38 5,550 15 Barley 0.09 0.19 150 <l Cabbage 0.22 0.38 950 <2.5 Com 0.06 0.25 28,700 <1 Cucumbers 0.2 0.25 500 <2.5 Dry 0.09 0.25 414,000 15 Beans/Peas LimaBeans 0.08 0.19 950 10 Peas (Fresh/Green 0.13 0.19 <50 <l /Sweet) Soybeans 0.15 0.38 3,084,800 5 Strawberries 0.22 0.38 2,200 5 Sunflowers 0.11 0.25 1,233,950 50 Tobacco 0.18 0.38 173,500 45 Tomatoes 0.11 0.38



## - <2.5 Watermelons 0.11 0.25 400 <2.5 Wheat 0.06 0.19

- <l Source: EPAProprietary Data, 2004-2013 and 2008-2012.

Corn Sulfentrazone is applied at an average application rate of0.06 lb/Ato approximately 28,700 total acres annually, orless than onepercent ofthe comcrop (EPA Proprietary Data, 2008-2012). Although only appliedto a limitednumber ofacres, comwas considered inthis analysis given the overall importance ofthis crop inU.S. agriculture. In com, sulfentrazone is recommended for the control ofa number ofdifficult to control weeds such as cominon waterhemp, giant ragweed, and marestail (Owen, 2011). Overall, for com sulfentrazone controls several difficult to control weeds and is slightly less expensivethan several ofthe competing herbicides. 

### Dry beans/peas Sulfentrazone is applied at an average applicationrate of0.09 lb/Ato approximately415,000 total acres annually, or 15 percent ofthe dry beans/pea crop (EPAProprietary Data, 2008-2012). In dry beans/peas, sulfentrazone is used inNorth and SouthDakotafor the control ofALS Page 3resistant kochia, anemerging problem weed, with 6 to 8 weeks ofresidual control (Zollinger, 2004 and Deneke et. al., 2009). Based on EPA Proprietary Data (2009-2013), sulfentrazone is the second most used herbicide for the control ofkochia and other resistant weeds. In dry beans/peas, sulfentrazone effectively controls ALS resistant kochia and is comparable in price to available herbicides. 

### Soybeans Sulfentrazone is applied at an average application rate of0.15 lb/ A to over 3 million acres annually, or 5 percent ofthe soybean crop (EPA Proprietary Data, 2009-2013). In soybeans, sulfentrazone is recommended as part ofa resistance managementprogram for control of glyphosate resistant Palmer amaranth which can cause extensive crop loss (Sprague, 2013). Of the herbicides used to control Palmer amaranth on soybeans, EPA Proprietary Data showthat, on average, from 2009 to 2013 sulfentrazone was the sixth mostused active ingredient and accounted for 9% oftotal acre applications. Sulfentrazone is applied aerially to 2% oftotal soybean acres nationally (Chism et. al., 2015). In soybeans sulfentrazone effectively controls glyphosate resistant Palmer amaranth and is comparable in price to other available herbicides. 

### Sunflower Sulfentrazone is applied at an average application rate of0.11 lb/ A to over 1.2 million acres annually, or 50 percent ofthe sunflower crop (EPA Proprietary Data, 2009-2013). In terms of percent crop treated, sulfentrazone appears to be an important chemical control in sunflower production. In sunflowers, sulfentrazone is recommended in Montana for control ofALS resistant kochia, a difficultto control weed (Petroff, 2002). Across the United States, sulfentrazone is the most used active ingredient for controllingkochia on sunflowers. Sulfentrazone is applied aerially to 5% ofsunflower fields (Chism et. al., 2015), effectively controls ALS resistant kochiaon sunflowers, and is comparable in price to other available herbicides. 

### Tobacco Sulfentrazone is applied at an average application rate of0.18 lb/A to 174,000 acres annually, or 45 percent ofthe tobacco

- crop (EPA Proprietary Data, 2009-2013). Interms ofpercent crop treated, sulfentrazone appears to be an important chemical control for tobacco production. In tobacco, inNorth Carolina sulfentrazone is one ofthe few herbicides recommended for control ofyellow nutsedge, an aggressive and difficult to control perennial weed (Bailey et al., 2014). According to EPA Proprietary Data, sulfentrazone is primarily used against morningglory, redroot pigweed, and nutsedge species. In tobacco sulfentrazone effectively controls yellow nutsedge and is comparable inprice to available herbicides. 

### CONCLUSION Sulfentrazone is used for control ofherbicide resistant weeds and difficult to control weeds in corn, dry beans/peas, soybeans, sunflower, and tobacco. In these crops, sulfentrazone is comparable inprice to other available alternative herbicides. Sulfentrazone is generally soil directed using ground equipment with lowbooms and larger droplet sizes. Aerial applications account for 2% ofthe total soybean acres and 5% ofthe total sunflower acres treated with

Page4sulfentrazone. Aerial treatments occurwhen fields are too wetfor ground equipment and when treating large acreage fields.

REFERENCES Bailey, A., T. Lax, B. Hill. 2014. Comparison ofHerbicide Systems for DarkFire-Cured Tobacco. Plant and Soil Sciences Research Report Vol. 3, No. 1, 2014. Accessed online onApril 20, 2015 at http://www.uky.edu/Ag/TobaccoProd/FactSheets/PSSRR/2014/Bailey%20Vol%203%20 No%201.pdf Chism, W., 

### J. Alsadek, E. Hill. 2015. Sulfentrazone Usage Information (PC# 129081). EPA, Office ofPesticide Programs, Biological and Economic Analysis Division. Deneke, D., M. Moechnig, and L. Wrage. 2009. Weed Control in Pulse Crops 2009. Accessed online onApril 17, 2015 at http://www.sdstate.edu/ps/extension/weedmgmt/upload/FS525PC.pdf EPA. 2015a. Proprietary Data 2009-2013. EPA. 2015b. Addendum to the Environmental Fate and Ecological Risk Assessmentfor Sulfentrazone Registration Review. Environmental Fate and Effects Division. Owen, M. 2011. 2011 Herbicide Guide for Iowa Corn and Soybean Production

. Accessed online onApril 17, 2014 at http://www.weeds.iastate.edu/reference/10%20ACU%20WC94.pdf Petroff, R.. 2002. Sunflower Production inMontana. Updated: May 28, 2002. Accessed online onApril 17, 2015 at http://ipm.montana.edu/MPIN/Cropfiles/sunflower.html Sprague, C. 2013. Palmer amaranthmanagement in soybeans. Accessed online onApril 17, 2015 at http://www.msuweeds.com/assets/ExtensionPubs/50737FINALFactSheetPalmerAmarant h-2.pdf WSSA. 2014. Herbicide Handbook, Weed Science Society ofAmerica, Tenth Edition, 2014. Zollinger, R.. 2004. Spartan and dry bean desiccants. Accessed online on April 17, 2015 at http://www.northarvestbean.org/BeanDay04/zollinger.pdf

Page 5