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

## DEC 12 2014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION
MEMORANDUM
SUBJECT: FROM:

THRU:



### TO: BEAD Chemical Profile (BCP) for Registration Review: Diclosulam (129122) Leonard Yourman, Biologist Biological Analysis Branch Rafael A. Prieto, Environmental ProtectiOn

## Speciali~

# Jt:C,**~** Science Information and Analysis Branch

## /7""'1**~** / /l Derek Berwald, Economist

# c;;?'~**~** Economic Analysis Branch Biological and Economic Analysis Division (7503P) Arne!Jones, Chief

# ~~ Biological Analysis Bran , ch 

### 1 . "**~** A**i4~ ,**  Diann Sims, Chief

### --**It ~** **~** Science Information and Analysis Branch Timothy Kiely, Chief

# ~**~"\ \,~**  Economic Analysis Branch**~** Biological and Economic Analysis ivision ( ) Sue Bartow, Chemical Review Manager Risk Managementand Implementation Branch4 Pesticide Re-evaluation Division (7508P)

Product Review**~anel:** November 26, 2014

lINTRODUCTION The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pest management roles and quantitative usage information for diclosulam. The BCP includes summaries ofprevious BEAD products and available public and/orprivate use and usage data for diclosulam to describe the role ofthis chemical in pest management. Additional information onuse is available in the diclosulam Label Data Report. Informationprovided in this BEAD Chemical Profile (BCP) maybe used by stakeholders (e.g., users and registrants), OPP risk assessors, and OPP risk managers, and the general public during the Registration Reviewprocess ofthis pesticide. Diclosulam was first registered in 2000. According to the Screening Level Usage Analyses (SLUA) (BEAD, 2014) diclosulam is only used onpeanut with an average of4,000 pounds active ingredient (a.i.) applied and an average percent crop treated (PCT) of20%. There is an active label (Strongarm, 62719-288) allowing use on soybeans in some states although BEAD has no usage data for this use site.
USE SITES Diclosulam is used for production ofpeanuts and is registered in Alabama, Arkansas, Florida, Georgia, Illinois, Louisiana, Missouri, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia. There are 24(c) Special Local Needs (SLN) registrations indicating a special local need for diclosulam to control tropical spiderwort inpeanut in Georgia, Floridaand Mississippi. Diclosulam is labeled for use on soybean in Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Missouri, NewMexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. A single preplant soil incorporated application, soil surface application, or a preemergent incorporation may be made. BEAD has no information or usage data suggesting that diclosulam is actually used on soybean fields. There are two diclosulam SLN labels for cottonwood plantings in Missouri and Tennessee.
FORMULATIONS AND APPLICATION METHODS Diclosulam is registered as a dry flowable formulation in water soluble packets. Diclosulam is labeled for soil applications for mostpeanutproduction. Itmay be applied preplant incorporated into soil, preplant surface application, orpreemergence through the soil "cracking"phase ofthe peanut emergence (i.e., germinatingplantbreaking through the soil). Forthe 24(c) registrations to control tropical spiderwort, diclosulam should be applied to the weed atthe 1to 2 leafstage while it is actively growing. Forthis use, the chemical can be applied from the soil cracking phase to the initiation offlowering, but no later than 30 days afterplanting. For soybean, a single preplant soil incorporated application, soil surface application, or a preemergent incorporation is indicated on at least one label (Strongarm, 62719-288).

2

### HISTORY OF DICLOSULAM AND BEAD PRODUCTS There is no record ofBEAD documents relating to diclosulam. 

### USAGE For the 2000-2012 timeframe, the annual usage ofdiclosulam averaged 4,000 pounds a.i. treating an annual average of200,000 acres ofpeanuts, with an overall average applicationrate of0.02 pounds a.i. per acre. As shown inFigures 1 and 2, usage for peanut, both in terms ofpounds a.i. and interms oftotal areatreated (TAT) has slightly decreased since a minorpeak in 2005 (Proprietary Data, 2000-2012). The SLN labels effective for Georgia (initially in 2004), Florida (2007), and Mississippi (2008), which allows applications post-emergenceto control tropical spiderwort may help to explain some ofthe higher use after 2003 indicated in Figures 1 and 2. According to the SLUA (BEAD, 2014) diclosulam is onlyused onpeanut with 4,000 pounds active ingredient (a.i.) applied and an average percent crop treated (PCT) of20%. Georgia and Alabamausage constitute over 80% ofdiclosulam pounds used on peanut fields (Table 1 ). BEAD proprietary data showno use for soybean. Usage Trends 

### FIGURE 1. 

### Diclosulam TotalArea Treated in Acres (2000-2012) on Peanuts

VI QJ

..... u <( c: !;{ !:::. "C (IJ
..... tU QJ

..... 1- tU QJ

..... <( ftj

..... 0 1- 350,000

0 0

..... 0 0 0 0 N N N 

### 8 N
Source: Proprietary Data, 2000-2012 ,.,., 0 0 N '<t LJ') 0 0 0 0 N N 10 0 0 N Year ,.... 00 0 0 0 0 N N en 0 0 N 0

..... ..... ..... 0 0 N N N

..... 0 N



### 3

### FIGURE 2. 

### Diclosulam TotalPounds Applied (2000-2012) 

### on Peanuts 6,000

<i: VI "'C r.:::: :::::s 0 a..

0 M N m**~ ~** **~ ~**  00 m 0 M N 0 0 0 0 0 0 0 0 0 0 M M M 0 0 0 0 0 0 0 0 0 0 0 0 0 N N N N N N N N N N N N N Year Source: Proprietary Data, 2000-2012


### TABLE 1. 

### States with Highest Use ofDiclosulam on Peanuts-Share of National Use ofDiclosulam (2008-2012) 

### Share ofNationalUse of Average AI Rate State Diclosulam (%) 

### (lbs/acre) Georgia 46 0.017 Alabama 36 0.020 Florida 8 0.016 North Carolina 6 0.016 Virginia 4 0.017 Source: Propnetary Data, 2008-2012

4Geographic Distribution ofDiclosulam Use Figure 3 shows the geographic distribution ofdiclosulam use. The map shows that diclosulam is used in states that growpeanuts except inthe peanut growing areas ofTexas, Oklahoma and NewMexico where diclosulam use is prohibited by label.

PoundsActive Ingredient per 1,000 Crop Acres Grown UNoData

- <0
.001

- 0
.001

- 0.05

. 0
.05-0
.1

- >0.1 Figure 3. Annual Average agricultural use intensity ofdiclosulam (2008-2012). More information about this map is presented in Appendix A.



### 5CHEMICAL AND USE CHARACTERISTICS Diclosulam is a triazolopyrimidine sulfonanalide chemical ofthe acetolactate synathase (ALS) inhibitor group ofherbicides (WSSA Group 2). Therefore, it will not control ALS-resistant weeds. It was originally developed for broadleafweed control inpeanut and soybean (Clewis and Wilcut, 2004).
ROLE OF DICLOSULAM IN PEST MANAGEMENT Diclosulam is used for broadleafcontrol-itprovides good to excellent control ofbristly starbur, wildpoinsettia, eclipta, and copperleaf. Ithas provided poor control ofsicklepod and inconsistent control ofnutsedges (Marshall, 20 12). Several herbicides ofdifferent chemical groups are available for preplant incorporation orpre-emergent application and generallyprovide a range ofefficacy against the various problem weeds. Forexample, imazethapyr (also an ALSinhibitor) is effective against nutsedges. Commonly, more than one herbicide are used to expand the range oftargeted weeds. The product label restricts the use ofdiclosulam in Oklahoma, Texas, and NewMexico due to alkaline soils and the risk ofcrop injury. In field plot experiments diclosulam applied preemergent resulted in 50% crop injury (Dotray et al., undated). The SLN labels approved for Georgia, Florida, and Mississippi for the postemergence use ofdiclosulam to control tropical spiderwort indicate that there is a value for diclosulam with a different use pattern. In alkaline soils research in Texas indicatedthat post-emergence use reduced the incidence of crop injury observed in preplant orpre-emergence applications (Dotray et al., undated). Currently diclosulam is labeled for preplant orpre-emergence soil application in peanut production in Alabama, Arkansas, Florida, Georgia, Illinois, Louisiana, Missouri, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia. Diclosulam is one among several herbicides that can be used inpeanut production. The preharvest interval for diclosulam is 30 days. In soils with iron-induced chlorosis the use of diclosulam may exacerbate the effect. Soybeans and peanut may be planted without a rotation interval restriction after peanut crops where diclosulam has been used. There are substantial restrictions on rotations to other crops after the use ofdiclosulam, however. These range from four months for wheat and barley to 30 months for sugarbeets, sunflower, and other crops that do nothave a specified rotation interval. Diclosulum is labeled for use on soybean in Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Missouri, NewMexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. According to the pesticide label, a single preplant soil incorporated application, soil surface application, or a preemergent incorporation may be made. A wide range ofbroadleafweeds are targeted although additional herbicides may be necessary to increase the efficacy against some weeds (e.g., nutsedges). However, BEAD has no informationthat diclosulam is actually used on soybean fields.

6DATA NEEDS The Agency currently does not have complete information on use and usage ofdiclosulam for peanutproduction. Obtaining additional information may improve future assessments conducted by the Agency related to the use and importance ofdiclosulam. For example, BEAD has little information as to additional possible niche uses, use patterns, or specific problem weeds where diclosulam might fill a need that is currently lacking for growers. The 24( c) labels indicate a potential value for postemergence use for tropical spiderwort. Onthe otherhand, the presence of ALS-resistant weeds will likely reduce the usefulness ofdiclosulam where resistant populations have developed or where resistant populations develop or spread. Information onchanges inuse and usage as a result ofweed resistance may help determine the future use trends for diclosulam and ultimately the comparative benefits ofthe herbicide. BEAD information indicates no use ofdiclosulam in soybean fields inthe U.S. Information on diclosulam use on soybean fields in general and particularly in Texas, Oklahoma, and New Mexico may be valuable. These are areas where use onpeanut fields is prohibited and where diclosulam-induced injury to peanuts has been observed. BEAD has no information on diclosulam SLN uses for cottonwood plantings. Presumablythere is some benefit not available with other herbicides. Information onparticularweed issues may be helpful ifa benefits assessment is required.
REFERENCE BEAD. 2014. Diclosulam Screening Level Usage Analysis. Biological and Economic Analysis Division, Office ofPesticide Programs, U.S. Environmental Protection Agency. Clewis, S. B. and Wilcut, J. W. Economic assessment ofdiclosulam and flumioxazin in stripand conventional-tillage peanut. 26th Southern Tillage Conference. Auburn University Extension. http://www.ag.aubum.edu/auxiliary/nsdl/scasc/Proceedings/2004/Clewis3.pdf Dotray, P. A., Murphree, T. A., Light, G. G., Grichar, W. J., Keeling, J. W., Baughman, T. A., Langston, V. B. (Undated) Weed control systems inpeanut with diclosulam postemergence. Texas A&M AgriLife Research & Extension Center at Lubbock.http://lubbock.tamu.edu/programs/disciplines/weeds/peanut/weed-control-systems-in-peanutwith-diclosulam-postemergence/ Marshall, M. 2012. Weed Control inPeanut. South Carolina Pest Management Handbook for Field Crops. Clemson University Extension. http:/ /www.clemson.edu/extension/rowcrops/pest/files/2012%20PMH%20Web%20Page%20Ver sion/2012%20PMH PEANUTWC.pdf Proprietary Data. 2000-2012.

7APPENDIX A The map included herein is primarily for the use ofthe risk assessors in the Environmental Fate and Effects Division. The map provides a very broad geographical view ofthe amount (in pounds) ofthe active ingredient applied per 1,000 acres of"land in farms". These data are included inthe maps because risk assessors are interested in the amount ofa pesticide used across farmland. Because ofthe definition ofLand in Farms, as discussed below, the calculated values presented inthe map are not equivalent to an application rate (lbs ai/ A). The data used to make these maps have many limitations. Any interpretation ofthe maps should considerthe underlying data and the associated limitations carefully. The smallest areas shown onthe maps within each state are Crop Reporting Districts (CRD). CRDs are defined by USDA and each consists ofmultiple counties that have similar soils, growing conditions, and farming practices. The CRDs within many states have roughly the same area. Because it is not feasible to conduct an agricultural survey that samples every county in the United States, the use ofCRDs allow for a sample to be collectedthat represent a much larger area with relatively homogeneous agricultural characteristics. The numerator (annual average pounds applied) is based onprivate market surveys ofpesticide use in agriculture averaged over the last five years (Proprietary Data, 2007-2011). 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 inevery crop in every year • Many specialty crops with very small acreages are not included in the survey The result ofthese limitations is that CRDs that showno usage may actually have a small amount ofthe active ingredient being used. The denominator (1,000 Acres oflandin farms) was selected from the 2007 Census of Agriculture (http:/ /www.agcensus.usda.gov/Publications/2007/Full Report/Volume 1, Chapter 1 US/usv1. pdt) to represent agricultural acreage that is actively managed and includes most ofthe areas

8treated withpesticides. The category "Land in Farms" is defined bythe Census ofAgriculture as being made up offour components: • Total cropland • Permanent pasture • Total woodland • Land in farmsteads, buildings, livestock facilities, ponds, roads, wasteland, etc. This category includes land in the various USDA conservation programs. It should be noted that the Census ofAgriculture does not include grazing land rented (on a per-animal basis) from the Bureau ofLand Management orForest Service, thus it is an underestimate ofthe land being managed for agricultural purposes. The reader 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. Scale and units ofmeasurement do matter and may be different between maps.

9