UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

NOV 0 6 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

BEAD Chemical Profile (BCP) for Registration Review: Diuron (035505) 

Sunil Ratnayake, Biologist 

Biological Analysis Branch ~h~ ... V'~ Sepehr 

Science 

Haddad, 

Information 

Environmental 

and Analysis 

Protection 

Branch 

Specialist 

'1-~ Stephen Smearman, Economist ./' ./ I tJ 

Economic 

Biological 

Analysis 

and Economic 

Branch 

Analysis Division 

~~ 

(7503P) 

Arnet Jones, Chief 

Biological Analysis Branch. j) . DiannSims,Chief ~~In ,j,~ Science Information ana Analysis Iifanch t 

Economic 

Timothy Kiely, 

Analysis 

Chief 

Branch ~ lA.\, ~ 

Biological and Economic Analysis ivision ( 503 ) 

Kathrine St. Clair, Chemical Review Manager, RMIB II 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: October 15, 2014 
SUMMARY 

Diuron was first registered in the United States in 1967 and it is used as a pre and post-emergent 

herbicide, algaecide, and mildewcide (USEPA, 2003). Diuron is a broad-spectrum residual 

herbicide registered for control ofbroadleaf and annual and perennial grassy weeds. In the U.S., 

diuron is registered for the control of weeds in agricultural crops (see use sites below). Also, it is 

used in non-agricultural sites such as irrigation and drainage systems, industrial and rights of 

way uses, and total vegetation control where it is used in combination with other herbicides. 

A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 

that provides the percent crop treated for 31 crops. For diuron, during the SLUA timeframe of 

2004-2012, usage for cotton and oranges had the highest use in terms of average pounds active 

ingredient (a.i.) used with 1.4 million lbs a.i. for cotton with an average 25 percent crop treated, 

and 1.2 million lbs a.i. for oranges with an average percent crop treated of 45 percent. The 

highest percent crop treated over the SLUA timeframe is for asparagus with an average 65 

percent crop treated. These percent crop treated numbers for cotton, oranges and asparagus may 

indicate high benefits of diuron for these crops. 

INTRODUCTION 

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

overview of the pest management roles and quantitative usage information for diuron. The BCP 

includes summaries of previous BEAD products and available public and/or private use and 

usage data for diuron to describe the role of this chemical in pest management. Additional 

information on use is available the LUIS Label Data Report and Screening Level Usage Analysis 

(SLUA). Information 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 

Diuron registered agricultural use sites include: alfalfa, apples, artichokes, asparagus, bananas, 

barley, caneberries, citrus, clover, com, cotton, grapes, nut trees, mint, oats, papayas, pasture, 

peaches, pears, peas, pineapple, sorghum, sugarcane, ornamental trees, flowers and shrubs and 

wheat. 

Non-Agricultural Use Sites 

Diuron registered non-agricultural use sites include: paints and coatings; adhesives, ornamental 

fish ponds, and catfish production; patios, rights-of-way and industrial sites. Residential uses 

include ponds, aquariums, and paints. 

Page2 
FORMULATIONS AND APPLICATION METHODS 

Diuron is formulated as a liquid, emulsifiable concentrate, dry flowable, flowable concentrate, 

pellet/tablet, and ready-to-use solution. 

Applications are made using the following equipment: ground sprayer, aerial equipment, and 

chemigation. 

HISTORY OF DIURON and BEAD PRODUCTS 

Diuron was first registered in the United States as a pre and post-emergent herbicide, algaecide 

and mildewcide in 1967 (USEPA, 2003). A Reregistration Eligibility Decision (RED) was 

completed for diuron in 2003. 

Benefits Assessments - A search of BEAD's Official Records data base for BEAD benefits 

assessments specifically for diuron did not find any records of prior BEAD assessments 

specifically for this chemical in the last 1 0 years. 

A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 

that provides the percent crop treated for 31 crops. For diuron, during the SLUA timeframe of 

2004-2012, usage for cotton and oranges had the highest use in terms of average pounds active 

ingredient (a.i.) used with 1.4 million lbs a.i. for cotton with an average 25 percent crop treated, 

and 1.2 million lbs a.i. for oranges with an average percent crop treated of 45 percent. The 

highest percent crop treated over the SLUA timeframe is for asparagus with an average 65 

percent crop treated. 

There were no emergency exemption requests for diuron in the last 1 0 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 request may yield information about a 

particular chemical's importance or value that is not found in other EPA records. However, a 

lack of Section 18 assessments by BEAD does not specifically indicate the relative importance of 

the chemical. 

USAGE 

Agricultural Usage 

Based on private market usage data from 1998-2012, usage averaged approximately 4.1 million 

pounds active ingredient (a.i.) applied annually on approximately 4.9 million acres treated. The 

average a.i. rate over this time period was pounds 0.84lbs a.i./acre. Figure 1 presents diuron 

usage in pounds a.i. and total area treated in acres over the 1998-2012 timeframe (Proprietary 

Data, 1998-2012). Figures 1 shows that over this time period in terms of pounds applied and 

acres treated there has been a modest decline in use although recently there has been a slight 

increase in the total number of acres treated from 2010-2012 compared to the years 2006-2009. 

Page 3 
FIGURE 1. Diuron Usage in Pounds Active Ingredient and Total Area Treated in Acres 

(1998-2012) 

7,000,000 

0 

Pounds AI Total Area Treated 

Source: Proprietary Data, 1998-2012 

Since the Re-registration Eligibility Decision was issued in 2003, the two timeframes below 

(1998-2003 and 2007-2012) were selected to compare a time period before the RED was issued 

and the most recent time period. 

Table 1. Comparison of Crops with Highest Use of Diuron- Percent of Total Lbs. 

Applied (1998-2003 and 2007-2012)_ 

1998-2003 2007-2012 

Average annual= 4.7 million lbs/yr Average annual = 3.3 million lbs/yr 

Crop %Lbs Crop %Lbs 

Orange 40% Cotton 37% 

Cotton 29% Orange 35% 

Grapefruit 6% Alfalfa 8% 

Alfalfa 5% Walnuts 4% 

Sugarcane 4% Grapefruit 3% 

Other 16% Other 13% 

TOTAL 100% TOTAL 100% 

Source: Proprietary Data, 1998 -2012. 

Table 1 shows that the crop with the most pounds applied during both the 1998-2003 and 2007-

2012 timeframes have been oranges and cotton accounting for approximately 70 percent oftotal 

pounds applied. The average annual usage in pounds has decreased approximately 30 percent 

from 4.7 million lbs/year to approximately 3.3 million lbs/year in the 2007-2012 timeframe. 

Page4 
Table 2o Comparison of States with Highest Use ofDiuron- Percent of Total Lbso Applied 

(1 998-2003 and 2007-2012) 

1998-2003 2007-2012 

Average annual= 4.7 million lbs/yr Average annual= 3.3 million lbs/yr 

State %Lbs State %Lbs 

Florida 38% Florida 28% 

California 17% California 21% 

Texas 15% Georgia 13% 

Louisiana 7% Texas 10% 

Other 23% Other 28% 

TOTAL 100% TOTAL 100% 

Other states in both time periods includes 30 additional states. 

Source: Proprietary Data, 1998-2012 

As shown in Table 2, Florida, California and Texas were the top states with the highest use of 

diuron in both time frames accounting for approximately 70 percent of total pounds applied in 

the 1998-2003 timeframe, and approximately 60 percent in the latter timeframe, even though 

total pounds applied has dropped 64 percent between the two periods. 

Application Rates 

The average a.i. rate for the top crop (cotton) in terms of pounds a.i. applied was 0.44 lbs 

a.i./acre. The average a.i. rate for oranges is 1.91 lbs a.i./acre as shown in Table 3. 

T a e bl 3 0 n· 1uron u se on T C op rops: A verage A I R t 0 0 a e, 2007 -2012 

Annual Average Annual Average Avgo Aolo Rate (lbs Crop Pounds Total Acres aoi.lacre) Treated* 

Cotton 1.23 million 2.78 million 0.44 

Oranges 1.13 million 593,000 1.91 

Alfalfa 278,000 312,000 0.89 

*Total Acres Treated sums all acres treated for a crop, mcludmg those acres that receive multiple treatments. 

Source: Proprietary Data, 2007-2012 

Geographic Distribution ofDiuron Use 

Figure 3 provides a very broad geographical view of the average annual amount (in pounds) of 

diuron applied per 1,000 acres of crop acres grown. The calculated values presented in the map 

are not equivalent to an application rate (lb a.i./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 of diuron based on pounds active ingredient applied. 

As shown in the map, Florida and New Jersey depict a high use intensity of acres treated with 

diuron. Please see Appendix I for a more detailed explanation of the information presented on 

Page 5 
the map. 

FIGURE 2. Annual Average Agricultural Use Intensity ofDiuron (2008-2012) 

Pounds Active Ingredient 

per 1,000 Crop Acres Grown 

0 <6 

0 6-19 

D 2o-3o 

- 31-129 

- >129 

0NoData 

Non-Agricultural Usage 

Most available non-agricultural usage data for diuron is limited and dated. There are two data 

sources for non-agricultural usage. These are the publically available USDA's National 

Agricultural Statistics Service (NASS) 2006 and 2009 Nursery and Floriculture reports, and the 

proprietary Kline & Company data. In addition to NASS 2006 and 2009 data which reported 

2,300 lbs a.i. used in 2006 and 3,300 lbs a.i. used in 2009 for nursery, other reported data is 

available from Kline for the years 2002, 2004, 2006 for nursery/greenhouse, 2004 and 2006 for 

landscape/lawn care operators, and 2003 and 2005 for aquatic areas as shown in Table 4. Total 

non-agricultural usage between 2003 and 2005 appears to have increased for aquatic areas, and 

between 2004 and 2006 for nursery/greenhouse, however, more recent data (post-2006) are not 

available to determine if this trend has continued since only one category of non-agricultural 

usage (turf and ornamentals) was available for 2011 showing 3,700 lbs a.i. used. 

Page 6 
Table 4. Diuron Non-Agricultural Usage (Pounds A.I) (2002-2011) 

Site 2002 2003 2004 2005 2006 2011 

Aquatic Areas N/A 500 N/A 28,000 NIA N/A 

Landscape/Lawn Care N/A NIA 2700 N/A 6200 NIA 

Operators 

Nursery/Greenhouse 7100 N/A 5100 N/A 6800 NIA 

Turf & Ornamentals N/A N/A N/A NIA 100 3700 

N/A= Not Available 

Source: Proprietary Data 2002-2011 

BIOLOGICAL ASPECTS RELEVANT TO DIURON 

Diuron is a systemic herbicide belongs to chemical family of urea (Group 7). Herbicides in this 

family interfere with photosynthesis. Diuron is primarily applied before the emergence of the 

crop and weeds. Diuron has residual activity and continues to control weeds until the crop 

become competitive with weeds. Diuron may also be applied as directed post-emergence 

treatments to avoid contact with crop foliage. Diuron can also be applied as a bum-down 

treatment to control annual weeds before planting. Diuron is taken up from soil solution by the 

root system and rapidly translocated into stems and leaves by moving primarily via the xylem. 

ROLE OF DIURON IN PEST MANAGEMENT 

Diuron is a broad-spectrum herbicide with residual activity and it is registered for the control of 

broadleaf and annual and perennial grassy weeds in agricultural and non-agriculturallands. 

Cotton and oranges are the top agricultural crops with the highest usage of diuron (Table 3). In 

cotton production, diuron is tank-mixed with bum-down herbicides to achieve a longer residual 

activity (Steckel, 2014). According to a publication in Georgia, diuron is a unique tool for cotton 

growers as it offers excellent control of small emerged Palmer amaranth. (Culpepper, 2012). In 

citrus production, tree growth and yield can be reduced due to the weed competition. Preemergence application of diuron is recommended to minimize these yield reductions (Futch and 

Sing, 2014). 

As previously mentioned a SLUA was prepared by BEAD for this chemical in 2014 that 

provides the percent crop treated for 31 crops. For diuron, during the SLUA timeframe of2004-

2012, for cotton, the percent crop treated was an average of25 percent, and for oranges the 

percent crop treated averaged 45 percent. The highest percent crop treated over the SLUA 

timeframe was for asparagus with an average 65 percent crop treated. These percent crop treated 

numbers for cotton, oranges and asparagus may indicate high benefits of diuron for these crops. 

Bermudagrass (Cynodon dactylon), crabgrass (Digitaria ischaemum and D. sanguinalis), 

goosegrass (Eleusine indica), and Johnsongrass (Sorghum halepense) are major grass weeds 

controlled by diuron. cocklebur (Xanthium strumarium L),jimsonweed (Datura stramonium), 

hop hornbeam copperleaf (Acalypha ostryifolia), common lambsquarters (Chenopodium album), 

Page 7 
pigweeds (Amaranthus spp.), prickly sida (Sida spinosa), common purslane (Portulaca 

oleracea), common ragweed (Ambrosia artemisiifolia), horseweed (Conyza canadensis) are 

major broadleafweeds susceptible to applications of diuron. Most of these weeds are found in 

crop production fields in the southern United States. 

The major non-agricultural use sites of diuron are roadside vegetation management, industrial 

sites and other non-agricultural use sites are listed under the heading of non-agricultural use sites 

of this document. Furthermore, diuron has been used as an algaecide and mildewcide agent in 

paints. 

It has been reported that total of 144 weed species identified with resistance to different modes of 

action of herbicides in the United States. Ofthese weed species, 9 were found to have developed 

resistance to the herbicides belongs to family of urea herbicides. In these 9 weeds, biotypes of 5 

weed species have shown resistance to diuron herbicide (Heap, Undated). 

DATA NEEDS 

The Agency currently does not have complete information for diuron for some of the herbicide 

uses and for antimicrobial (algaecide and mildewcide agent) l!Se. Obtaining information on the 

annual number of pounds and the average rates for applied diuron on a national level for roadside 

and other rights-of-way vegetation management uses as well as antimicrobial application rates, 

timing and amount of active ingredient used would be helpful to our future assessments. 

REFERENCES 

Biological and Economic Analysis Davison (BEAD). USEPA, 2014. Diuron Screening Level 

Usage Analysis. Biological and Economic Analysis Division, Office ofPesticide 

Programs, US Environmental Protection Agency. 2014 

Cotton Weed Control. 2014. Online Publication available at: 

http://extension.missouri.edu/p/G4251 .Accessed on October 17, 2014. 

Culpepper, S. 2012. Georgia Cotton: Diuron, Direx Offer Flexibility- But Be Careful. Online 

Publication. Available at: http://agfax.com/20 12/04/04/georgia-cotton-diurun-direx-offerflexibility-but-be-careful/. Accessed on October 24, 2014. 

Futch, S. H .. and M. Singh. 2014. 2014 Florida Citrus Pest Management Guide: Weeds. 

University of Florida IFHS Extension Service Publication No. HS-107. Online 

Publication. Available at: http://edis.ifas.ufl.edu/cg013. Access on October 24, 2014. 

Heap, I. (Undated). The International Survey of Herbicide Resistant Weeds. Available at: 

http://www.weedscience.org/summary/CountrySummary.aspx. 

Accessed Date. September 3, 2014. 

Herbicide Handbook. 20 14. 1Oth edition. Weed Science Society of America. Sethoxydim. Pp 

413-414. 810 E. lOth Street, Lawrence, KS 66044-8897. 

Page 8 
Proprietary Data. 1998-2012. (pesticide agricultural usage data). 

Steckel, L. 2004. Southeast Farm Press. Online Publication. Available at: 

http.:/ I southeastfarmpress.com/ cotton/residual-cotton-herbicide-options-late-burndowntennessee. Accessed on Oct, 24, 2014. 

USDA, 2006 and 2009. NASS Nursery and Floriculture Report. Online Publication Available at: 

http://quickstats.nass.usda.gov/results/E4B4FA4B-15DB-35DO-A5CD-9889E6D7689F. 

Accessed on September 3, 2014. 

USEPA. 2003. Re-registration Eligibility Decision (RED) for Diuron. 

http://www.epa.gov/oppsrrd1/REDs/diuron red.pdf. Accessed on Oct. 24, 2014. 

Ware, G. W. 2000. The pesticide book. Fifth Edition. Fresno, CA. Thomson Publications. Pp 

193-194. 

Page 9 
APPENDIX I. 

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 a.i./ 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. 

Page 10