UNITED STATES ENVIRONMENTAL PROTECTI ON AGENCY WASHING TON , D

. C

. 20460 

## FEB 01 2012

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POL L UTION PREVENTION

SUBJECT: BEAD Chemical Profile for Registration Review: Simazine (080807)
FROM:

THRU:

TO: Bill Phillips, PhD, Agronomist 

## lit!//' Biological Analysis Branch 

# <IJJJI**~ ~k**  Jihad Alsadek, Economist

### .;/~ 

### /1-
.... . Science Information and Analysis Branch

Molly Clayton, Chemical Review Manager Risk Management and Implementation Branch 3 Pesticide Re-evaluation Division (7508P)


### Product Review Panel date: January 23, 2013

INTRODUCTION The purpose of this document is to convey usage information and a broad overview ofthe pest management roles of pesticides that are beginni ng to undergo registration review. The anticipated audience consists ofthe team of EPA staff currently evaluating the registra tion status 1of simazine , and eventually the general public. This document builds upon the data already provided in the usage and label use data package s that are also provided to Registration Review teams by BEAD. The document is based on information and data available to BEAD as of Januar y 23, 2013. HISTORY OF BEAD ASSESSMENTS FOR SIMAZINE A search ofthe BEAD Official Records databas e and the Office of Pesticide Programs FIFRA Section 18 Emergency Exemption data base did not find any benefits assessments or Section 18 emergency exemptions reque sts specifically for simazine. In April of2006 simazine went through the Environmental Protection Agency regi st ration eligibility decision (RED) where it was determined that "
... 

### with label amendments and changes as specified in this document and the 2003 IRED for atrazine, there is a reasonable certainty that no harm will result to the general US. population, infants, children, or other major id entifiable subgroups of consumers, from the use ofsimazine, atrazine, andpropazine." 1
HERBICIDE DISCUSSI ON Simazine is a triazine herbicide in the Weed Science Society of America, group 5 with the mechani sm of action ofinhibiting photo synthe s is at photosystem II. Simazine can be used postemergence to the weed as a foliar applied herbicide, however since it is readily absorbed through the root system, it i s primarily applied as a pre-plant incorporated or soil applied herbicide. On average , over the period of 2000 to 20 I0 the highest use in percent of total pounds of active ingredient was in com (53%) w ith the second highest percent of total use in oranges (22 %). This herbicide is important in crop production as it is able to control grass and some broadleaf weeds in grass crops such as com, and in other crops s uc h as tree fruits like oranges.
Corn Production Many of the preemergence uses and characteristics of simazine are close to that of atrazine; nevertheless, there are some significant diff erences b etween the two that will dictate how and when these two herbicides will be used in the production of crops such as com. Overall the weed spectrums of these two herbicides are very close; however simazine tend s to be a better grass herbicide than atrazine. Also, b ecause simazine is relativel y Jes s soluble than atrazine, simazine will remain at or near the surface of the soil where susceptible plants that germinate, or have recently germinated, will absorb the chemical. Once simazine is absorbed throu gh the root . system it translocates throughout th e plant and ultimately affects its control on the whole plant. The end re sul t is control of weeds where root absorption takes place. Atrazine is able to move vertically throu gh th e soil profile quicker than simazine which gives it a broader spectrum of weed control. The weed spectrum of atrazine includes large -s eeded broadleaf weeds that germinate deeper in the soil profile. In practical terms, simazine is a good partner herbicide for use with atrazine to control weeds in com. Combining these two triazine herbicides as a tank mix results in a system where there is control of grasses and broadleaf weeds at the soil surface as well as grass and broadleaf weeds

1 Registration eligib ility decision for s imazine
. April 06 , 2006. http://www .epa.gov /oppsrrd I/ REDs/simazine_red.pdf 2that germinate lower in the soil profile. However, it is important to remember that these two herbicides have the same mechanism of action (MOA) which means that they will need an additional herbicide(s) with alternative MOAs to assist in res is tanc e management. Using only herbicides with the same mechanism of action will hasten the selection for resistant weed biotypes. Orange Production The production of orange crops is as broad ranging as the geographic regions 

### in which they are produced. Oranges are produced commercially in states like Arizona, California, Florida and Texas. Because of the way the trees are spaced within an orange grove there is plenty of acreage that is not covered by the tree canopy giving weed species a large area to germinate and grow. Given the available sunlight, moisture and nutrients these areas of the orange groves are optimal places for weeds to thrive. It i s for this reason that orange producers utilize herbicides and mowing to achieve weed control in their groves. Because of the characteristics discussed in the text above, simazine is an imp ortant part ofthe herbicides used in orange production. More than a third of the acreage in orange production is treated with simazine at a ra te which can be j ust under double the per acre rate of corn.
COMMON FORMULATIONS AND APPLICATION METHODS Simazine i s formu lated either as a liquid, emul s ifiab le concentrate, dry flowable or a flowable concentrate. It is app lied by aerial and ground broadcast, band application, chemigation, and spot tr eatment. USE SITES Agricultural Use S ites Simazine is an herbicide registered for u se on caneberries, grapes, strawberrie s, citrus fruits, nut crops, pome fru its, stone fruits, artichokes, com, asparagus, uncultivated agricultural areas, kale, cabbage , kohlrabi, brussel sprouts, blueberries, alfalfa, avocado, and olives
. Non-Agricultural Use Sites Simazine i s an herbicide registered for use on forest trees , ornamenta l herbaceous plants , ornamental lawns and turf, ornamental woody shrubs and vines, ornamental trees, Chris tmas tree farms, nursery stock, farm buildings, non-agricultural areas, golf course turf, and shelterbelt plantings. USAGE Agricultural Usage Figures 1 shows the use of simazine in terms of annual total pounds active ingredient u sed on all crops for the period 1998

- 2011. During this time per io d (1998

- 2011), the annual total agricultural usage averaged approximately 6 milli on pounds a.i. to treat approx imately 4 million acres for an average app lication rate of 1.5 lbs. a.i. per acre. T he average annual application rate for com i s 1
. 1 lb. a.i. per acre, less than the overall average application rate of 1.5 lbs. a.i. p er 

### acre, while the average annual appli cation rate for oranges is 3.0 lb. a.i. per acre, which is double the annual overall application rate. 3

### Figure 1. 

### Agricultural Usage Data for Simazine on All C rops in Pounds A.I. (1998-2011) 8,000.000

PoundsA.I

.

0 00 C'l C'l C'l C'l C'l .-4 .-4 0 .-4 N rt') 0 0 0 0 0 0 0 0 N N N N

Source: Proprietar y Data, 1998 -2011 \I\ 1.0 

### g g N N Years

4 

## " 0 0 N 00 0 0 N C'l 0 0 .-4 0 0 N N .-4 .-4 0 NFigure 2 presents the annual total agricultural usage for the more recent 2007-2011 timeframe. Usage averaged approximately 5 million pounds active ingredient (a.i.) for 4 million treated acres with an overall application rate of 1.25 lbs. a.i. per acre. During this time frame, the crops with the highest use in terms ofpercent of total pounds of active ingredient app lied and acres treated are corn and oranges (See Table 1). On average , the states with the most agricultural usage in terms of percent of total pounds a.i. applied are California (22%), Illinois (16%) , Florida (15% each) , and Indiana (14%) (Proprietary Data, 2007-2011).


### Figure 2
. Agricultural Usage Data for Simazine Top Crops (2007-2011)
4,000,000

Pounds A. I.**orn**

--- O ranges

Source: Proprietary Data , 2007-201 1 

### Table l. 

### Simazine Top Crops in Terms of Percent of Total Pounds Applied, Total Acres Treated (TAT), and Average Annual Application Rates in Lbs. a.i. per Acre (2007-2011) %Total Acres Treated

Source: Proprietary Data, 2007-2011

5 Average Annual Application Rates 

### in Lbs. A.I./ A

### Non-Agricultural Usage Non

- agricultural usage of simazine is shown in Table 2. Use has fluctuated across all sectors, with a noted increase in the institutional and lawn care operator sectors in 2004
. This data are dated and presented here for reference. 

### Table 2. Simazine Select Non-agricultural Use

Segment/Site 2002/lb. a.i. Golf Courses 26,000 Institutional Turf 12,000 Landscape N/ A Lawn Care Operators (LCOs) 45,000 Nurseries/Greenhouses 122,000 TurfFarms 98,000 N/A: Not Available Source: Kline and Company, Inc ., 2002, 2004 , 2006 

### WEED RESISTANCE RELEVANT TO SIMAZINE 2004/lb. a.i. 55 , 000 329,000 N/A 220,000 

### 177,000 18,000 2006/lb
. a.i
. 59 , 000 10,000 12,000 186, 000 13,000 86 , 000

According to The International Survey of Herbicide Resistant Weeds2 

### there are currently ni ne simazine resistant weed biotypes reported (Table 3), all of which are also resistant to atrazine as well. All ofthese weed biotypes are troublesome in agronomic production, human health, turf maintenance and production, as well as maintenance and production of ornamentals. This level of res i stance could be important in the decision making process for many users when choosing herbicides for their herbicide programs. Table 3
. Weed species with biotYPes resistant to the herbicide active ingredient simazine. • Common Name Genus and Species 1 Annual Bluegrass Poa annua 2 Barnyardgrass Echinochloa crus-galli 3 Common Groundsel Senecio vulgaris 4 Common Ragweed Ambrosia artemisiifolia 6 Ladysthumb Polygonum persicaria 7 Lambsquarters Chenopodium album 8 Smooth Pigweed Amaranthus hybridus 9 Yellow Foxtail Setaria glauca Heap, I. The International Survey of Herbicide Resistant Weeds. Online. Internet. November 1 5. 2012. Available www .weedscience
. com

2 Heap, I. The International Survey of Herbicide Resistant Weeds. Online
. Internet. November 15 ,2012
. Available www. weedscience.com 6DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON SIMAZINE Additional information, in terms of average and maximum percent crop tr eated, pounds a.i. applied, average application rate, regional application, time of application, number of applications per year on non-agricultural sites, such as forest trees, farm buildings, ornamentals (trees, plants, woody shrubs and vines), from the registrant would improve future assessments of the importance of simazine and may be required as part of the registration review of this pesticide. REFERENCES: Proprietary Data, 2000

-20 I 0 Kline and Company , Inc. , 2002 , 2004 , 2006 USDA, 2006-2010. NASS Crop Reporting Districts
. Online: http: //www.ers.usda.gov/briefing/arms/resourceregions/resourceregions.htm#nass
. USDA, 2007. Census of Agriculture. Online: http: //www.agcensus.usda.gov/ Publications/2007/ index.asp
.

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### Appendix Agricultural Usage by Crop Reporting District Another measure of usage is the us e intensity. In this analysis, the use intensity is expressed as the pounds a. i. applied per acre of land in farms. This differs from the application rate, which is expressed as the pounds a.i. applied per treated area. The average app lic ation rate for the period 2007 to 2011 was 1.25 lb s per acre or 1250 lbs per 1000 treated acres. As shown in Figure 3, however, us e intensity i s 260 lbs per 1000 acres of farm land
. Figure 3 spatially represents simazine usage by crop reporting district for 2006-2010. The areas depicted in red on the map in southern Florida are the citrus growing areas.



### 8Figure 3. Simazine Usage 

### by Crop Reporting District (2006-2010)

Average Pounds Per 1.000 Acres of Farmland

- < 1 1

- 1 1- 29 CJ 30

- 58

- 59-13 5

- 136

- 2 60

This is a map of agricultural pesticide usage at the Crop Reporting District (CRD) level prepared by BEAD for use in the Environmental Fate and Effects Divisio n documents. Thes e maps are used to help visualize where the pesticide be ing considered is most likely to be used and can be helpful in scenario se lection and placing the exposure assessment in context. CRDs are boundaries created by USDA NASS which are aggregates of counties (USDA, 2010). Pes ticide usage is displayed as average pounds (for the years 2006- 2010) per 1,000 acres of farmland in a CRD to normalize for the variation in farm land between CRDs. Farmland acreage was obtained from USDA (2007)
. Farmland or " land in farms" is defined as follows: The acreage designated as "land in farms" consists primarily of agricultural land used for crops, pasture, or grazing
. It also includes woodland and wasteland not actually under cultivation or used for pasture or grazing, provided it was part of the farm operator ' s total operation
. Large acreages of woodland or wasteland held for nonagric ultur a l purposes were del eted from individual reports during the edit process. Land in farms includes CRP, WRP , FWP, and CREP acres. Land in farms is an operating unit concept and inc lude s land owned and operated as well as land rented from others. Land used rent free was reported as land rented from others. All grazing land, except land used under government permits on a per-head basis, was inc luded as " land in farms" provided it was part of a farm or ranch. Land under the exclusive use of a grazing association was r eported by the grazing association and included as land in farms
. All land 9in American Indian reservations used for growing crops, grazing livestock, or the potential of grazing livestock was included as land in farms. Land in reservations not reported by reservation, individual American Indians or nonNative Americans was reported in the name of the cooperative group that used the land. In many instances, an entire American Indian reservation was reported as one farm (2007 Census of Agriculture, USDA). Usage is based on private market surveys of pesticide use in agriculture (Proprietary Data, 2006-20 l 0). The survey data are limited to the states that represent the top 80-90% of acreage for the individual crops; therefore , use may be occurring in regions outside the scope of the survey. CRDs showing no usage of pestic ides may be due to either the lack of pesticide use in the region or non-participation in the agricultural surveys . In addition , across the years, there may be variations in the specific crops included in the CRD survey. This may result in a lower annual average for the CRD. This map displays ratio data (i
.e. , average pounds per 1,000 acres of farmland) summarized at a very highlevel. Readers are strongly cautioned against trying to over interpret the map without examination of the underlying data. The underlying data may explain some of the many reasons that a Crop Reporting District may have a high value for a particular active ingredient such as significant acreage (compared with the CRD as a whole) of a crop or crops with a high application rate and frequency of application
. The reader should pay particu lar 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 of measurement do matter and may be different between maps. Sources: Proprietary Data. 2006-2010 USDA, 2006-2010. NASS Crop Reporting Districts. USDA, 2007. Census of Agriculture.

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