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

## JUN 07 20ll

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM
SUBJECT: BEAD Chemical Profile for Registration Review: Prohexadione Calcium (112600) FROM: Monisha Kaul, Biologist

# ~h.aJ**~** Biological Analysis Branch

THRU:

TO: Rafael Prieto, Environmental Protection**spe i**  

### 'st**~** 

### Science Information and Analysis Branch 

### V( John Faulkner, Economist**~** 

### Economic Analysis Branch Biological and Economic Anal sis Division (7503 Arnet Jones, Chief Biological Analysis Br

. 1 

### Diann Sims, Chief 

# Jti.
.**~~(J-C,""",,~** Science Information and Analysis Branch Timothy Kiely, Chief 

# fl-**~ r~**  Economic Analysis Branch

### ~

# J \ Biological and Economic Analysis Division 3P) Katie Weyrauch, Chemical Review Manager Risk Management and Implementation Branch 5 Pesticide Re-evaluation Division (7508P)


### ProductReview Panel date: May 2, 2012 INTRODUCTION The purpose ofthe BEAD Chemical Profile is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofprohexadione calcium, a plant growth regulator that controls vegetative 1growth, and eventuallythe general public. This documentbuilds upon the data already provided inthe "Usage and Label Use DataPackages" that are also provided to Registration Reviewteams by BEAD. The document is based on information and data available to BEAD as ofApril 17, 2012. COMMON FORMULATIONS AND APPLICATION METHODS Prohexadione calcium is formulated as a dry flowable and may be applied by aerial and ground spray, and by spottreatment. USE SITES Agricultural Use Sites Prohexadione calcium is registered for use on apples, sweet cherries, peanuts, pears, and grasses grown for seed. NonAgricultural Sites Prohexadione calcium is registered for use on sod farms, ornamental lawns and turf. USAGE Based onprivate market pesticide usage data, prohexadione's annual agricultural usage averaged 13,000 pounds ofactive ingredient (A.I.) treating an average of51,000 acres from 2006-2010. The average application rate is about 0.25 pounds active ingredient per acre. (Proprietary data, 2006-2010) According to proprietary data, between 2000 and 2010, the only crop with any usage for this chemical was apples. A newtolerance was established for sweet cherries in 2011 therefore no usage is available as ofthis date. Usage data onpeanuts, pears, grasses grown for seed, ornamental lawns, andturfwere notreported. The states with the most agricultural usage 

### in terms ofbothpounds A. I. and total area treated were Washington and Michigan (Table 1). (Proprietary data, 2006-2010) T 

### bliP



### a e . t fT 

### t IU 

### ereen 0 

### oa b St t sage ,y 

### a e. State Pound A.I. (%) 

### Total Area Treated (%) Washington 63 51

Michigan 19 24 New York 8 13 Pennsylvania 8 I 10

2

### USE TRENDS In terms ofpounds applied, the use ofprohexadione on apples was relatively constant except for a spike in 2008 (Proprietary data, 

### 2000-2010). See Figure 1below. 

### Fi re 1. Total Pounds Re orted on Prohexadione's Use on Ales,2000-2010. 30,000



## o o o o N .-t o o N N o o N
Source: Proprietary 

### Data, 2000-2010 ,." o o N

ADDITIONAL 

### USAGE INFORMATION**~** o o N Lf') o o N Year ...... o o N 00 o o N o


### ..... o N



### Another measure ofusage is the use intensity. The use intensity is expressed as the average pounds A. I. applied per 1,000 acres ofland in farms. This differs from the applicationrate, which is expressed as the pounds A. I. applied pertreated acre. Figure 2 spatially represents prohexadione's use intensity in the US on apples, and that use intensity is relatively high in the northwest and in Michigan, regions with significant apple production.

3

### Figure 2. Prohexadione Calcium Usage on Apples 

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

Average Pounds Per 1,000 Acres of Farmland

_ <0 : 05 0
.05

- 0.10 

## D 0
.11- 0.34 0
.35

- 0.80

_ 0
.81-1.17 Proprietary Data, 2006-2010. USDA, 2006-2010. USDA, 2007
. This is a map of agricultural pesticide usage at the Crop Reporting District (CRD) level. CRDs are boundaries created by USDA NASS which are aggregates ofcounties

-(USDA, 2010). Pesticide usage is displayed as average pounds (for the years 2006-2010) per 1,000 acres offarmland in a CRD to normalize for the variation in farmland between CRDs. Farmland acreage was obtained from USDA (2007). Usage is based on private market surveys ofpesticide use in agriculture (proprietary Data, 2006-2010). The survey data are limited to the states that represent the top 80-90% ofacreage for the individual crops, therefore, use may be occurring in regions outside the scope ofthe survey. CRDs showing no usage of pesticides 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.

4

### BIOLOGICAL ASPECTS RELEVANT TO PROHEXADIONE CALCIUM Prohexadione calcium is a plant growth regulator (PGR) thatreduces vegetative growth by inhibiting the synthesis ofgibberellins, a natural plant growth hormone. Gibberellinregulates cell elongation and reducing its production decreases the length ofshoot internodes. Prohexadione calcium is a production management tool. For example, use ofthis PGR in tree crops decreases the amount ofpruning needed, allows for more lightpenetration, may improve fruit color, and reduces incidence offire blight (a bacterial disease ofapples and pears). 

### In grasses grown for seeds, prohexadione calcium may reduce the potential for lodging because it reduces vegetative growth in grasses. 

### Inpeanuts, the use ofprohexadione calcium decreases vegetative growth and aids mechanical harvesting. 

### HISTORY OFBEAD ASSESSMENTS FORPROHEXADIONE CALCIUM Prohexadione calcium was mentioned in anemergency exemption: "Using a combination of copper-based fungicides, streptomycin sulfate, oxytetracycline (under emergency exemption on apples), a biological control agent, fosetyl-Al, prohexadione, and pruning, it is possible to minimize the economic losses caused by the disease"[fire blight] (Chandgoyal and Rim, 2006). The informationpresented inthis emergency exemptionindicated that prohexadione calcium is a tool thatmay be used in the management offire blight under normal weather conditions. 

### INFORMATION THATMAY BE USEFUL FORBEAD'S FUTURE WORKON PROHEXADIONE CALCIUM Obtaining additional information onthe following items would improve future BEAD assessments ofthe importance ofprohexadione calcium and may be required as part ofthe registration review ofthis pesticide. • Description ofprohexadione calcium use sites other than apples (pounds, areatreated, application method by site). • Description ofthe primary uses ofprohexadione calcium. • Description offrequency ofuse ofprohexadione calciumto control fire blight including location,**crop/si~e,** application rates. 

### REFERENCES Chandgoyal, Tara, and ElisaRim, 2006. Request for Emergency Exemption Use ofAgry-Gent 10-W (Gentamicin Sulfate) in Michigan (06-MI-Ol, DP # 325345) onApples for the Control of Fire Blight Disease 

### (Erwinia amylorora), February 27,2006. Proprietary Data, 2000-2010, and 2006-2010. USDA, 2006-2010. NASS Crop Reporting Districts. Online: http://www.ers.usda.gov/briefmg/arms/resourceregions/resourceregions.htm#nass. USDA, 2007. Census ofAgriculture. Online: http://www.agcensus.usda.govlPublications/2007/index.asp. 5