UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHI N G TO N , D

. C

. 204 60 

## JUN 12 2013

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: BEAD Chemica l Profile for Registration Review: 2,4-DP-p (Dichlorprop-p) Case (2,4-DP-p acid, 2,4-DP-p dimethylamine salt (2,4

-DP-p DMAS), and 2,4

-DP-p EHE) (031402 , 031403,03 14 1 6,031464 and 031465) FROM:

THRU: Bill Phillips, Ph.D. Agronomist

## ~ Biological Analysis Branch

### ~ 

### Sepehr Haddad , Environmental Protection Special is•

# ~**~** Science Information and Analysis Branch :;;/'

# ~**~** ""' Derek Berwald, Ph.D. Economist

# ~~**___.,.~~~.,--** Economic Analysis Branch Biological and Economic Analysis Division (7503P)

Timothy Kiely, Chief 

# a VV\**~** Economic Analysis Branch Biological and Economic Analysis Di ·sion (7503P) TO: Christina Scheltema, Chemical Review Manager Risk Management and Implementation Branch 3 Pesticide Re-evaluation Division (7508P) 

### Product Review Panel date: April17, 2013

INTRODUCTION The purpose of this document is to convey usage informat ion and a broad overview of the pest management roles ofpesticides that are beginning to undergo registration review. Theanticipated audience consists of the team of EPA staff currently evaluating the registratio n status of 2,4-DP -p and eve n tual ly the general pub lic. This document builds upon the data already provided in the usage and label use data packages that are also provided to Registration Review teams by BEAD. The document is based on information and data available to BEAD as ofMarch 20, 20 1 3
. 2,4 -DP-p , or dichlorprop-p, is a postemergence herbicide th at controls actively growing annual and perennial broad le afweeds , trees and brush. In l awns, turf and pasture 2,4 -DP-p controls suc h hard to control b roadleafweeds as dande li on 

### (Taraxacum officina/ e) and ironweed 

### (Veronia altissima) whil e on roadsides, industrial s ites, rights-of-way, and forests many aggressive perennial weed spec ies plus tree and brush s pecies , s uch as multiflora ro se 

### (Rosa multiflora), are controlled. 2 ,4 -DP-p is a synthetic auxi n h er bicide that i s in the Weed Science Soc iety of America group 4 herbicides. The "-p " designation in the active ingredient (ai) indicate s that this i s the iso lated
" R " isomer, or the active fraction of th e ingredients. Based on the chemistry of this herbicide it is considered vola ti le (vapor pressure 1 x 1 

# o-s Pa (20 C)) and has little so il acti vity (Senseman, 2007). Th e mechanism of actio n of this herbicide is not well understood but the chemica l is thought to act much like th e endogenous plant hormone auxin. Auxins are primaril y responsible for cell e longation and cell division. The mode of action of this herbicide is abnormal cell growth and e longation at the growing p o int s and plant nodes, le af attachments, and internodes, length of stem between node s. The abno rmal growth re sults in a d istorted and con stricted vascular system and ultimately total blockage of the vascular system. This herbicide is used in p remixes o f mu ltip le herbicides that are broadcast over l awns and turf in o rder to control difficult to manage broadleaf weeds. Overall this is the predominant use of this herb icide with 60% of the annual total of four million pounds applied. T hi s herbicide is commonly formulated into ready-to-use turfgrass products that contain multipl e herbicides as well as some containing fertilizers. These produc t s are used to control a bro ad spectrum of weeds, primarily broadleaf weeds, in a variety of turfgrasses in commercial and homeo wner settings. One of th e most common product mi xtures is 2, 4 -D+dichlorprop-p (2,4-DP -p) + mecoprop -p, whic h is used to control numerous problematic broadleaf wee d species in turf grass . Anoth er area where this herbicide is used i s in the control of trees and brush. App li cation s to trees and brush are via "s pray to wet" foliage us in g wat er a s the diluent and several specialized m eth od s t hat sometimes in c lude mixing the h erbicide with oil or dies e l fuel. One of the application methods u s ing t he oil or diesel fu el mixt ure is the basal bark application where the lower t runk of th e tree is treated. In addition, thi s mixture can also be applied as a cut-stump trea tmen t where applications are made to the freshly c ut stump of a tree. This type of treatment is used to prevent any regrowth of the tree from t he stum p or any below ground vegeta ti ve propagules
. Additi onally, 2,4 -DP-p can be applied as a frill treatment where th e tree is c u t into with an axe around the circumference of the lower trunk and the inside of the c ut i s then treated with the herbicide mixture.
2The herbicide 2,4

- DP

- p ( dichlorprop

-p) was initially reg i st ered in 1968. The Reregistration Elig ibility Decision (RED) document was issued in 2007. As a part of the RED the use of aerial application was removed from the label and changes were made to the use rate. BEAD has not identified alternatives or evaluated the benefits to 2,4-DP-p in past work , including the RED process, so little background information is available. COMMON FORMULATIONS AND APPLICATION METHODS 2 ,4

- DP

- p is formulated as granular , emulsifiable and solub le concentrate, wettab le powder, Ready-to-Use solution. Methods of application are by boom sprayers, handheld nozzle or wand sprayers, knapsack sprayers, and granu lar spreaders.
USE SITES Agricultural Use Sites 2,4-DP-p is registered for use on pasture. 2,4 -DP-p is not registered for any food crops in the United States. Non-agricultural Use Sites 2,4-DP-p is registered for use on ornamental lawns, recreational turf, sports fie l ds , sod farms, roadsides, industrial sites, rights-of-way , and forests.
USAGE Agricultural Usage Note: all rates in this document are expressed in pounds acid equivalent (a.e
.). Acid equivalent is the acid portion of the active ingredient (a.i
. ). Based on private market usage data from 1998

- 2011, agricultural usage averaged approximately 8,000 pounds a. e. on approximate ly 24,000 acres ofpas ture treated. The average rate over this time period was 0.334 pounds a.e./acre. Pasture was the only site for which private market usage data was reported. Figure 1 presents 2 ,4

- DP

- p (dichlorprop) usage in pounds a.e. over the 1998- 2011 t imeframe. Figure 2 presents total area treated in acres over the same timeframe (Proprietary Data, 1998-2011 ). The use of 2 , 4

- DP-p has fluctuated over ti me , but there is no discernible trend
.

30 1998 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Years 

### So urce: Proprietary Data, 1998-2011 FIGURE 2. 2 ,4 -DP- Use on Pasture Total Area Treated in Acres (1998 -20 11) 100,000
.

0

- 1998 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Years 

### Source: Proprietary Da ta, 1998-2011 According to a previous BEAD analysis (2013), nationally less than o n e p ercent ofpasture is trea ted with 2,4-DP-p. Generally, such a low p ercentage would indi ca t e that a chemical plays a very minor role in pest contro l because , f or example , target pests are not that important or more cost-effective alternatives are available
. In 

### thi s case , however, it needs to be considere d that pasture produ ctio n is a very low-input activity in c omparison to crop production. Further , u se o f 2,4- DP-p on pasture appears to be geographically concent rated. The states with the highest use 4of2,4-DP-p on pastureland in the 2007-2011 timeframe are listed in Table 1. The majority of use is in Missouri (70%) , followed by Tennessee ( 17%) (Proprietary Data, 2007-2011). This information sho uld be used with caution, because these data are from surveys where there are very few samples in the survey that show use of2,4 -DP-p
. 

### TABLE 1. 

### States with Highest Use (Missouri & 

### Tennessee) of2,4 DP-p- Percent of Total Lbs. Applied, Total Acres Treated, and Average Application Rates from 2007 to 2011 State %Total Lbs %Total Average Annual A.E. Applied Acres Application Rates Treated (Lbs A.E./A) Missouri 70% 74% 0.294 Tennessee 17 % 17% 0.315 

### Source: Proprietary Data, 2007-2011
Non-Agricultural Usage In terms of non-agricultural usage, data are available from Kline & Co. up until 2006, but since the data are dated , the information for non-agric ul tura l usage included in this section is based on information provided to the Age ncy by the 2,4-DP-p Task Force (registrants of2,4

- DP-p) and reflected in the 2007 RED. The Task Force provided information stating that the majority of2,4-DPp is co-formulated with other chloropheno xy herbicides for use on residential lawn s, wit h smaller usage in other recreational turf and other non-agricultural grassy areas. Based o n usage information provided by the 2,4-DP-p Task Force in 2007 , total annual domesti c usage of2,4-DP-p is approximately 4 million pounds: 60% is applied to residential turf , 10% is applied to sod farms, 9% is applied to golf courses 8% is app lied to sports turf, 8% is applied to commerc ial turf; and 5% is applied to uncultivated non-agricultural land. According to the Task Force, geograph ical use area s for applications to turf are in roughly the following descendin g order : Midwest , No rtheast, South , Northw est, and West (U.S. EPA, 2007).


### ROLE OF PESTICIDE IN PEST CONTROL This herbicide is an important component in contro lling many of the problematic broadleaf weeds in homeowner and commercial turf grass by broadening the spectrum of weeds that these product mixtures can control. For homeown ers products containing this herbicide are easy to use and convenient for the control of aesthetically displeasing weeds s uch as dandelion. In addition to the turf grass use there are those uses that are important but for which there is not a lot of chemical required, such as brush and tree applications. Pasture use is small and does not require a lot of chemical; however , BEAD is unaware of whether this use is important to pasture weed control.

5INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 2,4-DP- p BEAD is unsure why the majority of the agricultural use is centered in the state of Mi ssour i , or why specific areas show up as high use areas in the private data. In addition, BEAD does not have data to provide information on the current use of this herbicide in turf grass other than what was provided in the RED. If these areas and us es are considered significan t in the future registration review risk assessments the task force may need to provide some informa tion regarding these uses . REFERENCES BEAD. 2013. 2 ,4 -DP Screening Level Usage Analysis. Biological and E conomic Analysis Division, Office of Pesticide Programs, US Envi ronme ntal Protection Agency. January 30. Proprietary Data. 1998-2011. Senseman, S.A. 2007
. Herbicide Hand Book Ninth Edition. Weed Sci. Soc. of Am. 810 E. 

### lOth Street, Lawrence, KS 66044-8897. U.S.A. USDA, 2007. Census of Agriculture. Online: http: //www.agcensus.usda.gov/Publications/2007/ index.asp
. U.S
. EPA, 2007. Reregistration Eligibility Decision for Dichlorprop-p (2,4-DP-p). Online at: http://www .epa. gov 

### IoppOOOO 1 

### Ichem _search/reg_actions/reregistration/red
_ PC-031402
_ 29- Aug07.pdf



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