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

## NOV

# ro 20"

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM
SUBJECT:
FROM:

THRU:

TO: BEAD Chemical Profile for Registration Review: Diflufenzopyr (005108) and Diflufenzopyr-sodium (005107) Bill Phillips, II, PhD,

# AgrOnOmi**~** Biological Analysis Branch

### ~ 

# f / Sepehr

### Haddad, EnvironmentalProtection Specialist 

# h./;w-u
Science Information and Analysis Branch 

# 7 Derek Berwald, Economist 

# .G r 

# 4 VI\:**~** Economic Analysis Branch

### ~

# J
. Biological and Economic Analysis Divlsion (7503P Arnet Jones, Chief Biological Analysis Branc Diann Sims, Chief

# ~ Science Information and Analysis Branch

# 95~ Timothy Kiely, Chief Economic Analysis Branch 

## J

# . Biological and Economic AnalYSlS Division (7503P) Julia Stokes, Chemical Review Manager Risk Management and Implementation Branch**~** Pesticide Reevaluation Division (7508P) 

### ProductReview Panel date: October 26, 2010
INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest managementroles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status 1ofdiflufenzopyr and diflufenzopyr-sodium, and eventually the general public. This document builds upon the data already provided in the 

### "Vsage and Label 

### Vse DataPackages" that are also providedto Registration Review teams by BEAD. The document is based oninfonnation and data available to BEAD as ofOctober 2011. Diflufenzopyr-sodium is applied as a postemergence herbicide that controls annual and perennial broadleafweeds as well as some grass species in agricultural and non-agricultural sites. The herbicide diflufenzopyr-sodium is a semicarbazone with the mechanism ofaction of inhibiting the transportation ofthe synthetic (e.g. herbicides and growth regulators) and the miturally occurring planthonnone auxin (e.g. indoleacetic acid). Weed control is achieved by causing the buildup ofauxins at the growing points (shoots and roots) ofplants. This chemical is classified as a group B herbicide bythe Weed Science Society ofAmerica. Currently in the V.S. there have been no reports ofresistant weed biotypes ofany plant species. Atthis time there is no known mechanism in plants known to convey resistance to this herbicide.


### USE SITES Agricultural 

### Vse Sites Diflufenzopyr-sodium is labeled for use on com (field, pop and sweet), wheat, cotton, soybeans, forage grasses, hay, rangeland, and non-crop areas. The only registration for diflufenzopyr is a technical registration. Non-Agricultural 

### Vse Sites Diflufenzopyr-sodium is labeled for the following non-agricultural use sites: airports, rights-ofway, tank farms and fence rows. 

### COMMON FORMULATIONS AND APPLICATION METHODS Diflufenzopyr-sodium is fonnulated as water dispensable granules or emulsifiable concentrate. It is applied as foliar, soil and seed treatment. . Application methods are broadcast (spray and banded) and aerial.


### USAGE Agricultural 

### Vsage Based onprivate market usage data from 2001-2010, usage averaged approximately 120,000 pounds active ingredient (a.i.) for 3.2 million acres treated. Figure 1presents diflufenzopyrsodium usage overthis time period. The average a.i. rate was**approxim~tely** 0.04 pounds per acre during 2001-2006, and decreased to about 0.03 pounds per acre from 2007-2010.**~e** crop2with the major use interms ofpounds a.i. applied and total area treated is com with close to 100% ofthe total use; however, very minor use was reported on soybeans, cotton and sweet com during 2001-2010 (Proprietary Data, 2001-2010). 

### FIGURE 1. 

### Diflufenzo yr-sodium Usa e on Corn 180,000 ,--------- --------- ---



### o 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Source: Proprietary Data, 2001-2010

KANSAS

4% WISCONSIN 4%OHIO 4%

5%
7% Source: Proprietary Data, 2001-2010 Years

7%



### 3As shown in Figure 1, the use on compeaked in 2002. From 2001

- 2010, an average of3.1 million com acres were treated with diflufenzopyr-sodium; the amount applied on com over the same period averaged about 100,000 lbs. a.i. Although applied to a large acreage, that acreage is well under 5% ofthe com crop. Itappears that use has beentrending down, with a temporary reversal when comprices and acreage increased in 2007. Figure 2 presents the states with the most agricultural usage in terms ofpounds a.i. applied. These are: Minnesota (15%), Illinois (14%), Iowa (12%) followed by North Dakota, Nebraska, and Indiana each at (7%), and South Dakota, Ohio, Wisconsin, and Kansas at 5% or less. The "other" category ofstates which comprise 21% ofthe usage include Texas, Colorado, Michigan, Kentucky, and Missouri among other states. Non-Agricultural Usage Usage data are not available for the labeled non-agricultural use sites for diflufenzopyr-sodium.
BIOLOGICAL ASPECTS RELEVANT TO DIFLUFENZOPYR-SODIUM Diflufenzopyr-sodium is usually sold inproduct mixtures with dicamba. This is due to the unique way that the two herbicides interact to result in the control ofbroadleafand grass weed species. Because diflufenzopyr-sodium inhibits the transport ofthe naturally occurring plant hormone indoleacetic acid and the synthetic auxin-like plant hormone dicamba, these plant hormones become concentrated inplant shoots and roots. Weed control is achieved through this buildup ofbothnatural and synthetic auxins at the plant's growing points (shoots androots). As a result ofthis action, reduced rates ofdicamba can be used to obtain the same weed control efficacy as the full rate. Currently inthe U.S. there have been no reports ofweed biotypes resistant to diflufenzopyrsodium. This is postulated to be because there is no known mechanism for resistance to this group ofherbicides in plants.
BEAD ASSESSMENTS FORDIFLUFENZOPYR-SODIUM Although there have not been any BEAD assessments ofdiflufenzopyr-sodium in recent years, it appears that diflufenzopyr-sodium does not have particularly high benefits. Itis applied to a relatively small share ofthe total com acreage, and use appears to have beentrending down over time. INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK BEAD will appreciate any information on uses where diflufenzopyr-sodium is particularly important orhas few alternatives, or situations where the standard alternatives are unavailable. This data will assist analysts in characterizing any use ofthis herbicide that may be vital to a specific production system.

4REFERENCES 

### Proprietary Data, 2001-2010. Senseman, S.A. Herbicide Handbook, Ninth Edition. 2007. Weed Sci. Soc. OfAmerica. Lawrence, Kansas 66044-8897



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