UNITED STATES ENVIRONMENT AL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

JUN 11 2015 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

Fenoxaprop and Fenoxaprop-ethyl Qualitative 

& 128701) 

Bill Chism, Ph.D., Senior Biologist 

Biological Analysis Branch 

Michelle Ranville, Ph.D., Economistr ('(\~ ry-:} 

Biological 

Economic Analysis 

and Economic 

Branch 

Analysis Division 

U ~ 

(7503P) 

Biological 

Arnet Jones, 

Analysis 

Chief 

Branch ~~(J 

(I r'1 ~ I• 

Timothy Kiely, Chief ~ ~ \~ J 

Economic Analysis Branch 1 \". · 

Biological and Economic Analysis ivision (750 

Miguel Zavala, Chemical Review Manager 

Tracy Perry, Team Leader 

Kelly Sherman, Acting Chief 

Risk Management and Implementation Branch III 

Pesticide Reevaluation Division (7505P) 

BEAD Product Review Panel date: May 20, 2015 
SUMMARY 

Fenoxaprop and fenoxaprop-ethyl are undergoing registration review. As part of the risk 

management phas_e, the Biological and Economic Analysis Division (BEAD) conducted a 

qualitative assessment of the benefits of fenoxaprop and fenoxaprop-ethyl. Fenoxaprop-ethyl 

(PC Code 128701) is a post emergence herbicide used to selectively control annual and perennial 

grass weeds with labeled use sites on fallow, rice and soybeans. Fenoxaprop (PC Code 129092) 

has labeled use sites on fallow, barley, cotton, right-of-way, ornamentals, turf, rice, and wheat. 

Data in this document cover both active ingredients, fenoxaprop and fenoxaprop-ethyl; the two 

active ingredients are referred to collectively as fenoxaprop. This qualitative assessment reviews 

four example crops to determine whether fenoxaprop formulations are an effective tool for 

selective control of grass weeds in barley, rice, soybeans, and wheat (spring and winter). 

BACKGROUND 

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requires EPA to register 

pesticides before they can be distributed and used and to re-evaluate ·the registrations at least 

once every 15 years. FIFRA requires the EPA to regulate the use of a pesticide to the extent 

necessary to prevent unreasonable adverse effects on the environment, including human health, 

where 'unreasonable' is defined as taking into account the economic, social, and environmental 

costs and benefits of the use of the pesticide. 

The primary risk concern for fenoxaprop is to non-target terrestrial (monocot) plants, primarily 

from spray drift resulting from aerial applications. There have also been a series of incidents 

reported for grain crops treated with fenoxaprop. (EPA, 2014). 

Fenoxaprop-ethyl (PC Code 128701) and fenoxaprop (PC Code 129092) are post emergence 

herbicides used to selectively control annual and perennial grass weeds in numerous crops. 

Fenoxaprop inhibits acetyl CoA carboxylase enzyme (ACCase) (WSSA Group 1) and"interferes 

with meristematic tissue development. Grass herbicides like fenoxaprop can be a tool in the 

control of herbicide resistant (e.g., glufosinate, glyphosate, acetolactate synthase) volunteer com 

in broadleaf crops such as soybeans but unless they are used properly they can select for ACCase 

resistant weeds. ACCase herbicides have many herbicide resistant weeds with over 40 resistant 

weed species in the United States. 

For agricultural uses, fenoxaprop is generally applied early to late post emergence to the crop 

and weeds using ground equipment with low booms. Only two crops show significant aerial 

applications with 8% of total acres treated for barley (approximately 240 thousand acres) and 

53% percent of total acres treated for rice (approximately 87 thousand acres). (Chism et. al., 

2015) Data on application timing indicate that the rice aerial applications were made to 

accommodate the large number of acres involved and not specifically because of wet fields since 

they were applied pre-flood; only a small number of acres were treated post-flood. It appears 

that the barley aerial applications generally occurred late post so that the large fields could be 

treated in a short amount of time when the weeds were most sensitive. (Chism et. al., 2015) 

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QUALITATIVE BENEFITS 

Between 2009 and 2013, fenoxaprop has been shown to be used primarily on barley (20,000 lb. 

ai/year), rice (10,000 lb. ai/year), soybeans (20,000 lb. ai/year), and spring/winter wheat 

(200,000 lb. ai/year) (Chism et. al., 2015). Percent crop treated is approximately 10 percent for 

barley, 5 percent for rice, 2.5 percent for soybeans, and 10 percent for wheat. (Chism et al, 

2015) This assessment reviews these four example crops (selected based on highest proportion of 

usage) and concludes that fenoxaprop formulations are an effective tool for control of difficult to 

control weeds and prices are comparable or lower than alternatives . . 

Barley and Wheat 

In barley and wheat production in North Dakota, fenoxaprop provides excellent selective post 

emergence control of several difficult to control annual grass species such as wild oat, foxtail 

(green and yellow), and bamyardgrass (Zollinger, 2015). In barley and wheat in California, 

fenoxaprop is considered part of an integrated pest management (IPM) program for the control of 

canarygrass, wild oat, and foxtail (green and yellow) (Univ. of Cal., 2009). In barley and wheat, 

fenoxaprop formulations are used as part of an IPM program to control several difficult to 

control weeds and are less expensive than several of the alternative herbicides. 

Rice 

In rice production in Mississippi, fenoxaprop is recommended for control of several difficult to 

control annual and perennial grass species such as bamyardgrass, sprangletop, broadleaf 

signalgrass, johnsongrass (seedling), and fall panicum (MSU, 2015). In California fenoxaprop is 

recommended for control of sprangletop (California Rice Research Board, 2003). In rice, 

fenoxaprop formulations control several difficult to control weeds and are priced comparably to 

the alternative herbicides. 

Soybeans 

In soybeans in Alabama, fenoxaprop is recommended for selective post emergence control of 

several difficult to control annual and perennial grass species such as fall panicum, foxtail spp., 

and shattercane (ACES, 2015). Grass herbicides like fenoxaprop-ethyl are an important tool in 

the control of herbicide resistant volunteer com in broadleaf crops such as soybeans. In soybean 

fenoxaprop formulations control several difficult to control weeds including glyphosate-resistant 

com and are less expensive than several of the alternative herbicides. 

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CONCLUSION 

Fenoxaprop is used for selective post emergence control of difficult to control annual and 

perennial grass species in barley, rice, soybeans, and winter and spring wheat. As a post 

emergence treatment the grower can avoid making prophylactic preemergence applications. In 

these crops fenoxaprop is less expensive than some of the other available alternative herbicides. 

Fenoxaprop is generally applied early to late post emergence to the crop and weeds using ground 

equipment, with low booms. It is applied aerially to rice (53% of acres treated) to accommodate 

a large number of acres treated, and it is applied aerially to barley (8% of acres treated) so that 

large fields can be treated in a short amount of time when the weeds were most sensitive. 

REFERENCES 

ACES. 2015. Soybean, Insect, Disease, Nematode, and Weed Control Recommendations 2015. 

IPM-0413. Alabama Cooperative Extension System, Alabama A&M and Auburn 

Universities. Accessed online on April 24, 2015 at 

http://www.aces.edu/pubs/docs/I/IPM-0413/IPM-0413 .pdf 

California Rice Research Board. 2003. Weed Control in Rice. Accessed online on April 24, 

2015 at http://www.carrb.com/02rpt/Weeds.htm 

Chism, W., J. Alsadek, and M. Ranville. 2015. Fenoxaprop-ethyl Usage Information (PC# 

128701 & 129092). Biological and Economic Analysis Division, Office of Pesticide 

Programs, EPA. 

EPA. 2014. Environmental Fate and Ecological Risk Assessment for the Registration Review of 

Fenoxaprop-p-ethyl. Environmental Fate and Effects Division, Office of Pesticide Programs, 

EPA. 

Mississippi State University (MSU). 2015. Weed Control Guidelines for Mississippi. 

Mississippi State University. Accessed online on April 24, 2015 at 

http://msucares.com/pubs/publications/p 15 32.pdf 

Proprietary data. 2004-2013. 

University of California. 2009. Pest Management Guidelines, Small Grains. Accessed online 

on April 24, 2015 at http://www.ipm.ucdavis.edu/PMG/r7307001 l l.html 

Zollinger, R. editor. 2015. North Dakota Weed Control Guide. Hard Red Spring and Durum 

Wheat, Winter Wheat and Barley. Accessed online on April 24, 2015 at 

http://www.ag.ndsu.edu/weeds/weed-control-guides/nd-weed-control-guide-1/wcgfiles/3 .1-Wheat.pdf 

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