UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

SEP 2 3 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Oxadiazon (109001) 

FROM: Sunil Ratnayake, Ph.D., Biologist ?l. ~ V\}JI\ ~ 

THRU: 

TO: 

Biological Analysis Branch ~ ~ l 

Don 

Science 

Atwood, 

Information 

Ph.D., 

and 

Entomologist 

Analysis Branch 

£J-w-zv#' 11; ~ 

Economic 

Stephen Smearman, 

Analysis Branch 

Economist ~t..I/'/J ~ 

Biological and Economic Analysis Division (7503P) 

Arnet Jones, Chief 

Biological Analysis Branch 

Diann 

Science 

Sims, 

Information 

Chief 

and 

!9~~ Analysis Branch 

Timothy Kiely, Chief ~ lu.-j Economic Analysis Branch 

Biological and Economic Analy ·s Divis' (7503P) 

Joel Wolf, Chemical Review Manager 

Re-evaluation Management and Implementation Branch 2 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: September 10, 2014 

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SUMMARY 

Oxadiazon was first registered in the U.S. in 1978. It is a selective herbicide applied as pre and 

early post-emergence treatments for the control of many annual broadleaf and grass weeds. 

Major use sites of this chemical are established or newly established bermudagrass, perennial 

ryegrass, fescue turf, and various ornamentals, including landscape ornamental beds. There are 

no food or feed, or anticipated food or feed uses for oxadiazon. No agricultural usage data are 

available for this chemical and the highest non-agricultural usage of this chemical is on golf 

courses. 

INTRODUCTION 

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

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

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

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

information on use is available in the Oxadiazon Label Data Report provided in the public 

docket for this chemical. Information provided in this BEAD Chemical Profile (BCP) may be 

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

and the general public during the Registration Review process of this pesticide. 

AGRICULTURAL USE SITES 

There is no food or feed, or anticipated food or feed uses for oxadiazon. The Registrant is not 

supporting any tolerances for oxadiazon in the United States and existing tolerances have been 

revoked. (EPA, 2008) 

NON-AGRICULTURAL USE SITES 

Oxadiazon is registered for commercial use on turf grown in golf courses and in areas such as 

apartment/condominium complexes, parks, athletic fields, playgrounds, and cemeteries. In 

addition, oxadiazon is used on sod farms and on conifer nurseries and landscapes (i.e. industrial 

sites, ornamental, roadside plantings, woody, ornamental shrubs, vines and trees, and herbaceous 

ornamentals). 

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FORMULATIONS AND APPLICATION METHODS 

Oxadiazon can be formulated as a granular, wettable powder, emulsifiable concentrate, water 

soluble packets, and mixed with fertilizer. Application is made by ground using 

spreader/granular appli_cator or calibrated sprayer. 

IDSTORY OF OXADIAZON AND BEAD PRODUCTS 

Oxadiazon was registered in 1978. A Phase Four generic data call-in (DCI) was issued in May of 

1991. Due to additional data required under FIFRA as amended in 1988, the oxadiazon registrant 

decided to no longer support food uses of oxadiazon. On June 3, 2002, the Agency considered 

the FQP A safety finding to be met and counted the oxadiazon tolerances as reassessed. There are 

no CODEX, Canadian, or Mexican tolerances for oxadiazon residues. 

A search of the BEAD database for previous BEAD products for oxadiazon indicates that there 

are no records of prior BEAD benefits assessments or emergency exemption requests for 

oxadiazon in the last 10 years. Note that a lack of emergency exemption requests does not 

indicate the relative importance of the chemical. 

OXADIAZON USAGE 

Agricultural Usage 

There are no agricultural uses for oxadiazon. 

Non-Agricultural Usage 

Data for oxadiazon use on non-agricultural sites is limited to BEAD proprietary data. As shown 

in Table 1, golf course is the primary non-agricultural use site with approximately 78% of 

oxadiazon usage. 

Table 1. Usage ofOxadiazon on Various Non-agricultural Sites (2012) 

Segp~ent 1:. -

Golf 

Institutional Turf 

Landscape 

LCO 

Nursery/Greenhouse 

Turf 

Total 

1 Total may not add due to roundmg. 

Source: Proprietary data, 2012 

-

U~ag~ (lOOO lbs a.i.) 

212 

17 

19 

7 

5 

14 

273 1 

Page 3 

~~: .., 
BIOLOGICAL ASPECTS RELEVANT TO OXADIAZON 

Oxadiazon belongs to the family ofprotox-inhibiting herbicides and the mode of action ofthis 

herbicide family is inhibition of protoporphyrinogen oxidase enzyme. Inhibition of this enzyme 

in plants lead to interfering of chlorophyll production path way resulting in a breakdown of plant 

tissues on exposure to light. Injury symptoms include wilting followed by necrosis and 

desiccation (Herbicide handbook, 2014). Foliar applications ofthis herbicide shows injury 

symptoms within 1 to 2 days. Soil applied oxadiazon is readily absorbed by shoots of emerging 

seedlings and root absorbtion of seedlings is comparatively lesser than the shoot absorption. This 

herbicide accumulates in older plant parts with little movement to the growing points. 

ROLE OF OXADIAZON IN PEST MANAGEMENT 

Oxadiazon is a pre-emergence herbicide labeled for use on turfgrasses such as newly established 

bermudagrass, perennial ryegrass, and woody ornamentals (Herbicide Handbook, 2014). 

Oxadiazon controls most annual grasses and many small-seeded broadleaf weeds. The potential 

for injury limits the use of oxadiazon on zoysiagrass and St. Augustinegrass species. Oxadiazon 

can be safely used on dormant or actively-growing bermudagrass, bluegrass, perennial ryegrass, 

St. Augustinegrass, zoysiagrass and tall fescue. Oxadiazon fonnulations are not labeled for use 

on putting greens. Red fescue, bentgrass and centipedegrass are only marginally tolerant to 

oxadiazon. When applied as a pre-emergence treatment oxadiazon controls grass species such as 

crabgrass (Digitatria spp.) goosegrass (Eleusine indica), annual bluegrass (Poa annua) and 

annual sedge (Cyperus compressus). 

DATA NEEDS 

The Agency currently does not have important information on oxadiazon. Obtaining the 

following information for all registered non-agricultural sites may improve future assessments 

conducted by the Agency related to the use and importance of oxadiazon. 

Usage 

• Total pounds active ingredient applied 

• Percent crop/site treated 

• Application rates·: typical and maximum 

• Frequency of application by region of the country 

• Application Intervals by region of the country 

• Methods of application 

• Target or niche pests 

• Efficacy information/product performance 

Page4 
REFERENCES 

EPA. 2008. Oxadiazon RED Fact Sheet. Available at: 

http://www.epa.gov/oppOOOO 1/chem search/reg actions/reregistration/fs PC109001 20-Jun-08.pdf. Accessed on July 2, 2014. 

Herbicide Handbook. 2014. Tenth Edition. Published by Weed Science Society of America. 810 

E. lOth Street, Lawrence, KS 66044. 

Proprietary Data. 2004-2012. 

Proprietary Data. 2008-2012. 

Proprietary Data. 2012. 

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