UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

NOV 2_5 2013 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

BEAD Chemical Profile for Registration Review: Flucarbazone-sodium (114009) 

Sunil 

Biological 

Ratnayake, 

An~~

Ph.D., 

n~h

Biologist 

,9~ 

~ -""'\ 

\ 

~ 

Rafael Prieto,'Environmenf a{ Protection Specialist 

Science Informah on and Analysis Branch 

T J Wyatt, Economist ~ 1 ,/ _ 11 I'lL 

Economic Analysis Branch f(/ '/~ 19 ,)w.n&r- J(JI-$ 

Biologic and Economic Analysis Divisioh (7503P) 

Arnet Jones, Chief 

Biological Analysis Branc 

Science 

Diann Sims, 

Information 

Chief 

and 

~~ Analysis Branch 

Tim 

Economic Kiely, Analysis 

Chief 

Branch 

9J 1 

V 

A 

"\ 

A ~ Biologic and Economic Analysis ivision (7503 

Jolene Trujillo, Chemical Review Manager 

Risk Management and Implementation Branch 5 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel date: May 22, 2013 

SUMMARY 

Flucarbazone-sodium is registered for use on spring wheat, including durum, and winter wheat, 

grasses grown for seed, on conifers (plantations/nurseries), and on ornamental lawns and turf. 

Based on available usage information, flucarbazone-sodium may play a relatively important role 
in the control of weeds in spring wheat production, where about ten percent of the crop is treated 

annually. In winter wheat, only about one percent of the crop is treated annually, suggesting that 

flucarbazone-sodium plays a relatively minor role in weed control. However, recent data show 

that use in winter wheat may be increasing over the past several years. While many weed 

species have developed resistance to ALS-inhibiting herbicides such as flucarbazone-sodium, the 

fairly consistent use of this herbicide in wheat production for the past several years does not 

suggest that growers are having any particular resistance problems at this time that would deter 

them from using it. 

Flucarbazone-sodium may play a role in resistance management as a tank mixed product. 

Furthermore, as a post-emergence herbicide used in wheat production, it can provide growers 

with useful options if pre-plant or pre-emergence herbicides do not provide adequate control of 

weeds. Growers can use this herbicide as a post-emergence application to control competing 

weeds present in wheat fields such as wild oats, foxtails, and other grass and broadleaf weed 

species. However, there are several alternatives to flucarbazone-sodium that can be applied as 

post-emergence treatments for the control of similar weeds. 

BEAD does not have any information to assess the pest management role of flucarbazonesodium in grass grown for seed or in conifer and turf. 

INTRODUCTION 

The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an 

overview of the pest management roles and quantitative usage information for flucarbazonesodium. The BCP includes summaries of previous BEAD products and available public and/or 

private use and usage data for flucarbazone-sodium to describe the role of this chemical in pest 

management. Additional information on use is available in the flucarbazone-sodium PRD Label 

Data Report and the Screening Level Usage Analysis. Information provided in this BCP may be 

used by stakeholders (e.g., users and registrants), OPP risk assessors and risk managers, and the 

general public during the Registration Review process of this pesticide. The document is based 

on information and data available to BEAD as of October 2013. 

Flucarbazone-sodium was first registered in the U.S. in 2000. This herbicide is designated as a 

reduced risk herbicide. Flucarbazone-sodium belongs to the Sulfonylaminocarbonyltriazolinone 

group of herbicides (Weedscience.org, 2013) and it is a systemic herbicide used for the postemergence control of wild oat, green foxtail, and other grass and broadleaf weeds found in crop 

production fields and other sites described under the use sites. According to the Weed Science 

Society of America (WSSA) mechanism of action classification, flucarbazone-sodium belongs to 

the group 2 herbicides. The mechanism of action of this group of herbicides is inhibition of the 

enzyme acetolactate synthase (ALS) enzyme which is also called the acetohydroxyacid synthase 

(AHAS). Inhibition of this enzyme interferes with the biosynthesis of branched-chain amino 

acids such as valine, leucine, and isoleucine and initiates a cascade of events leading to the death 

of susceptible weeds. 

2 
USE SITES 

Agricultural Use Sites 

Flucarbazone-sodium is registered for use in spring wheat, including durum, winter wheat, 

grasses grown for seed, and conifers (plantations/nurseries). 

Non-Agricultural Use Sites 

Flucarbazone-sodium is registered for use on ornamental lawns and turf, including golf courses. 

COMMON FORMULATIONS AND APPLICATION METHODS 

Flucarbazone-sodium is formulated as water dispersible granules, emulsifiable concentrate, and 

soluble concentrate. Use in grass grown for seed is limited to soluble concentrate and use in 

conifers and turf is limited to the emulsifiable concentrate. This chemical is applied as broadcast 

and spot treatment. According to the information provided on the product label of Everest® 

herbicide, aerial and ground applications are recommended as the application methods of this 

herbicide. 

HISTORY OF BEAD ASSESSMENTS FOR FLUCARBAZONE-SODIUM 

BEAD has not previously assessed the benefits associated with the use of flucarbazone-sodium. 

USAGE 

Based on private market pesticide usage data from 2008-2012, flucarbazone-sodium's annual 

agricultural usage averaged 36,000 pounds of active ingredient (A. 1.) treating an average of2.4 

million acres, for an average application rate of 0. 015 pounds A. I. per acre. Use in grass seed, 

conifer, and turf production is not included in this estimate as usage survey data do not cover 

these sites. 

USE TRENDS 

Figure 1 shows the overall trend offlucarbazone-sodium use from 2001 through 2012. Use has 

risen steadily since registration in 2000. Use fluctuated around an average of 30,000 pounds A. I. 

applied per year in the latter half of the decade, but recent data suggests the upward trend may 

continue (Proprietary data, 2001-20 12). Thus, the average use reported here may underestimate 

future use. 

3 
Fi re 1. Total Pounds of Flucarbazone-sodium A 

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 

(Source: Proprietary data, 2001-2011) 

During this timeframe, spring wheat accounted for the largest percentage of usage in terms of 

total pounds of A. I. applied and total area treated. See Table 1 below. The average application 

rate of0.015 lb A.I. per acre is approximately the same for both winter and spring wheat. Less 

than 0.5 percent of the total amount was applied to fallow and barley according to survey data. 

These are not registered use sites and the survey results could indicate misuse, response errors in 

the survey, or reflect the respondents' interpretation of the question (e.g., fallowed land to be 

planted with wheat). 

Table 1. Flucarbazone-sodium's Top Crops in Terms of Avg. Lbs. Applied & TAT (2008-

2012) 

Crop Pounds Applied (A.I) Total Acres Treated 

Wheat, Spring 77.0% 77.8% 

Wheat, Winter 22.3% 21 .9% 

(Source: Propnetary data, 2008-2012) 

Over the 2004 to 2011 time period, about five percent of U.S. wheat acreage was treated each 

year, on average, with flucarbazone-sodium (BEAD, 2011). According to data from the U.S. 

Department of Agriculture (NASS, 2010), flucarbazone-sodium has been used on less than one 

percent of the U.S. winter wheat acreage. Use is somewhat more prevalent on spring wheat, with 

less than five percent of durum wheat treated and between seven and nine percent of acres in 

other spring wheat. 

4 
As seen on Table 2 below, flucarbazone-sodium's top states in terms of both pounds (lbs.) 

applied and total area treated (TAT) are North Dakota, Montana, and Minnesota. These three 

states accounted for about 80 percent of total acres planted to spring wheat in the U.S. between 

2009 and 2011 (NASS, 2012). There is substantial acreage of winter wheat in Montana as well. 

Table 2. Flucarbazone-sodium's Top States in Terms of Avg. Lbs. Applied & TAT (2008-

2012) 

STATE Pounds Applied Total Acres Treated 

North Dakota 63.0% 63.4% 

Montana 15.0% 13.5% 

Minnesota 5.8% 6.8% 

(Source: Proprietary data, 2008-20 12) 

Figure 2 depicts flucarbazone-sodium's agricultural usage, in terms of pounds applied, for winter 

and spring wheat (proprietary data, 2001-2012). Since about 2005, use in spring wheat has 

fluctuated from year to year, but does not appear to be trending up or down while use in winter 

wheat has been stable or increasing, especially in the most recent year data are available. 

Fi ure 2. Pounds of Flucarbazone-sodium A lied on Major Cro s er Year 

40,000 -.---- - ----- ----- --------------

"C 

.!!! 

ii 

Q. 

"' 

-lbs applied, Spring Wheat 

- - ·lbs applied, Winter Wheat 

/' ~ / ' -~ ~ / ' ,." .... --- - -/ ' .................... ,J' ~ .... ,. 

I 

I 

I 

I 

I 

I 

0 +---.--.--.---.--.--,---.--.---.--.--.--~ 

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 

Year 

Note: A minimum percentage of barley and fallow was treated with flucarbazone-sodium. 

(Source: Proprietary data, 200 1-20 12) 

5 
Geographic Distribution of Flucarbazone-sodium Use 

Figure 3 depicts the regions of the United States where use offlucarbazone-sodium is reported. 

The map indicates the relative intensity of use where the use intensity is expressed as the pounds 

A .I. applied per 1,000 acres of cultivated crop land. This differs from the application rate, which 

is expressed as the pounds A.I. applied per treated acre. The average application rate for the 

period 2008-2012 is 0.015 pounds A.I. per acre, or 15 pounds A.I. per 1,000 treated acres. As 

shown in Figure 3, however, use intensity range is well under one pound per 1,000 acres of crop 

land. The area of highest intensity is in North Dakota reflecting a relatively high percent of 

spring wheat treated with flucarbazone-sodium and a high proportion of spring wheat in 

farmland. Relatively low intensity of use is shown in Kansas, Oklahoma, and Texas. These 

three states account for almost 50 percent of winter wheat acreage in the U.S. (NASS, 2012), but, 

as noted above, less than one percent of U.S. winter wheat is treated with flucarbazone-sodium 

(NASS, 2010). 

Figure 3. Flucarbazone-sodium Usage by State (2008-2012) 

Pounds Acitve Ingredient 

per 1,000 Crop Acres Grown 

0No0ata 

D <O.o2 

- 003 · 012 

. 0.13 · 0.32 

- >0.32 

See Appendix A for explanation of the methodology and data used to generate Figure 3, as well 

as a discussion of data limitations and uncertainties. 

6 
CHEMICAL AND USE CHARACTERISTICS 

Flucarbazone-sodium belongs to the sulfonylaminocarbonyltriazolinone group of herbicides 

(Weedscience.org, 2013). Herbicides belong to this group inhibit the acetolactate synthase 

(ALS) enzyme which is also called the acetohydroxyacid synthase (AHAS). Inhibition ofthis 

enzyme interferes with the bio-synthesis of branched chain amino acids (valine, leucine, and 

isoleucine) in susceptible weeds (WSSA, 2013). Other major classes ofherbicides which inhibit 

this enzyme are imidazolinones, pyrimidinylthiobenzoates, sulfonylureas, and 

triazolopyrimidines. Variations on residual activity, crop selectivity, and spectrum of weeds 

controlled may be observed with the application of herbicides included in these classes (Univ. of 

Tennessee, 2013). The majority ofthese herbicides are systemic herbicides and they are active 

on annual and perennial weed species. The major weed species controlled by :flucarbazonesodium are green foxtail (Setaria viridis), wild oats (Avena sativa), barnyard grass (Echinochloacrusgalli), brome species (Bromus spp.), redroot pigweeds (Amaranthus retrojlexus), wild 

mustard species (Brassica spp.), curly dock (Rumex crispus), and Pennsylvania smart weed 

(Polygonum pensylvanicum). 

Generally, injury symptoms occurring due to the applications of ALS inhibitors appear within a 

week after the herbicide treatments. Significant symptoms are chlorosis, purple leaf veins, and 

bottlebrush appearance of roots in some weed species. Complete death of susceptible weed 

species may occur within two to three weeks after the herbicide applications. It has been reported 

that currently, 131 different weed species have developed resistance to ALS inhibiting herbicides 

in more than 400 locations in the world (Weedscience.org, 2013). Clodinafop, fenoxaprop, 

pinoxaden, and propoxycarbazone-sodium are some of the herbicides that can be used as alternatives 

to control wild oats, Italian ryegrass, and other grass weed species in spring wheat production 

(Morishita and Lyon, 2012). 

Flucarbazone-sodium is applied as a post-emergence treatment (herbicide applied after the 

emergence ofthe crop) in wheat. Generally, post-emergence treatments are highly effective when 

applied at the seedling stage of weeds. The use of post-emergence herbicides, including 

flucarbazone, is important when pre-plant or pre-emergence treatments do not provide adequate weed 

control. The alternatives noted above can also be use post-emergence. Furthermore, flucarbazonesodium is used for the selective control of grass and broadleaf weed species in tolerant cool and 

warm season turf grass species. In addition, this herbicide is used for the growth management and 

seedhead suppression of certain turf grass species (Align Product Label, 201 0). 

ROLE OF FLUCARBAZONE-SODIUM IN PEST CONTROL 

Given the low percentage of the crop treated, flucarbazone-sodium does not appear to play an 

important pest control role in winter wheat production. However, the relatively higher 

percentage of spring wheat treated suggests that :flucarbazone-sodium may be important for weed 

control in spring wheat production. While many weed species have developed resistance to 

ALS-inhibiting herbicides such as :flucarbazone-sodium, the fairly steady usage of this herbicide 

in wheat production for the past several years does not suggest that growers are facing resistance 

7 
problems at this time. Flucarbazone-sodium may play a role in resistance management, for 

example, in a tank mix in combination with herbicides with different mechanisms of action. 

As a post-emergence herbicide, it can provide growers with useful options if pre-plant or preemergence herbicides do not provide adequate weed control. Flucarbazone-sodium is likely to 

be an effective product for the control of wild oats, foxtails, Italian rye grass, and other grass 

weed species found in wheat. However, it is not unique in either the weeds it controls or in its 

use as a post-emergence herbicide. 

BEAD does not have sufficient information on the use of flucarbazone-sodium to assess its value 

in grass grown for seed, in conifer production, or in turf. 

INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 

FLUCARBAZONE-SODIUM 

The Agency currently does not have important information on some uses of flucarbazonesodium. To understand the role of flucarbazone-sodium in the production of grass seed, conifers, 

and turf, and any benefits it provides users, useful information would include 

• acres treated and application rates, 

• timing and frequency of applications, and 

• target pests 

REFERENCES 

Align Herbicide Product Label. 2010. Arysta LifeScience, North America LLC. 15401 Weston 

Parkway, North Carolina, NC 27513. Accessed on Nov, 5, 2013. 

BEAD. 201 3. Screening Level Usage Analysis. Biological and Economic Analysis Division, 

Office of Pesticide Programs, U.S. EPA. 

Morishita, D., and D. Lyon. 2012. Spring Wheat. Pacific Northwest Weed Management 

Handbook. E. Peachy, ed. Pacific Northwest Extension Publication, Oregon State 

University, Washington State University, and University of Idaho. Available at 

http://pnwhandbooks.org/weed/agronornic/cereal-grain-crops/spring-wheat. Accessed 

Date. May 15, 2013. 

NASS. 2012. Crop Production, 201 1 Summary. National Agricultural Statistics Service, U.S. 

Department of Agriculture. January. Available at 

http://usdaO l.library.cornell.edu/usda/nass/CropProdSu//20 1 Os/20 12/CropProdSu-0 l-12-

2012.pdf. Accessed Date. May 8, 2013. 

8 
NASS. 2010. 2009 Wheat Chemical Use. National Agricultural Statistics Service, U.S. 

Department of Agriculture. May. Available at 

http://www.nass.usda.gov/Oata and Statistics/PreDefined Queries/2009 Wheat Chern Usage/index.asp. Accessed Date. May 8, 2013. 

Proprietary data, 2001 -2011 

Univ. of Tennessee. 2013 . Mode of Action Definitions. University of Tennessee, Knoxville. 

Available at http://hortweeds.tennessee.edu/webapp/test/moa.htm. Accessed Date May 

6, 2013. 

Weedscience.org. 2013. International Survey of Herbicide Resistant Weeds. 

http://www.weedscience.org/summary/home.aspx. Accessed Date May 7, 2013. 

WSSA. 2013. Summary of Herbicide Mechanism of Action. Weed Science Society of 

America. Available at http://wssa.net/wp-content/uploads/WSSA-Mechanism-ofAction.pdf . Accessed Date May 8, 2013. 

9 
Appendix A. Flucarbazone Use Intensity by State (2008- 2012) 

The map included herein is primarily for the use of the risk assessors in the Environmental Fate 

and Effects Division. The map provides a very broad geographical view of the average annual 

amount (in pounds) of the active ingredient applied per 1,000 acres of crop acres grown. These 

data are included in the maps because risk assessors are interested in the amount of a 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 of the maps 

should consider the underlying data and the associated limitations carefully. 

The numerator (annual average pounds applied) is based on private market surveys of pesticide 

use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys 

cover about 60 crops and are targeted in states that produce the majority of the crop. Although 

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 types of pesticides are surveyed in every crop in every year 

• Many specialty crops with very small acreages are not included in the survey 

The result of these limitations is that states that show no usage may actually have a small amount 

of the 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 of all of the surveyed crops. This value is independent of pesticide usage and pesticide 

registration. It is important to note that the surveyed crops (about 60) are sampled from states 

that are major producers of each 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. 

The reader should pay particular 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. 

10