UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

NOV 17 Z014 

MEMORANDUM 

OFFICE OF CHEIJIICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: BEAD Chemical Profile for Registration Review: Dikegulac Sodium (109601) 

FROM: 

THRU: 

Carl Chen, Biologist 

Biological Analysis Branch 

Cynthia Doucoure, Environmental Protection Specialist L/J.f'\. " ~ ~~-·· ' 

Science Information and -Analysis Branch 

Derek Berwald, Economi. st ~ 

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~ --;_ ·" ~ 

Economic Analysis Branch 

Biological and Economic Analysis Division (7503P) 

Amet Jones, Chief 

Biological Analysis Branc 

Diann Sims, Chief 

Science Information and Analysis Branch 

Timothy Kiely, Chief ~ (AA.. ., Economic Analysis Branch 

Biological and Economic An y Division (7 ) 

TO: Matthew Manupella, Chemical Review Manager 

Risk Management and Implementation Branch (RMIB II) 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel date: November 5, 2014 

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SUMMARY 

Dikegulac sodium, a plant growth regulator, was first registered in the U.S. in 1978. It is used on 

ornamental plants in greenhouses, nurseries, and on landscapes, as well as deciduous evergreen 

and conifer tree farms. The Reregistration Eligibility Decision (RED) for Dikegulac Sodium was 

finalized in March 2007. Currently, there are three active Section 3 registrations for this 

chemical. 

Based on available data, dikegulac sodium appears to be used in very low amounts (400 lbs a.i.) 

in the nursery and floriculture sector in the U.S. (USDA NASS, 2006). California DPR, 

however, reports use of dikegulac sodium in higher amounts (approximately 1,400 lbs a.i. on 

average) in recent years (2008-2012), particularly for landscape maintenance. 

INTRODUCTION 

The purpose of this document is to convey usage information and a broad overview of the pest 

management roles of pesticides that are beginning to undergo registration review. The 

anticipated audience consists of the team of EPA staff currently evaluating the registration status 

of dikegulac sodium and eventually the general public. The document is based on information 

and data available to BEAD as of July 2014. 

COMMON FORMULATIONS AND APPLICATION METHODS 

Dikegulac sodium is formulated as soluble and emulsifiable concentrates, as well as liquid readyto-use. 

USE SITES 

Agricultural Use Sites 

Dikegulac sodium is labeled for use on farms for deciduous evergreen and conifer trees, 

including Christmas trees. 

Non-Agricultural Use Sites 

Dikegulac sodium is labeled for use in greenhouses, nurseries, and on landscape trees, hedges, 

shrubs, groundcovers, flowering plants and other ornamentals. Landscape areas include parks, 

school campuses, city streets, and similar recreational, institutional, or industrial areas. 

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DIKEGULAC SODIUM USAGE IN THE U.S. 

BEAD reviewed available data sources and found that only USDA NASS reported national use 

of dikegulac sodium in the nursery and floriculture sector in 2006, where approximately 400 lbs 

a.i. were applied at an average a.i. rate of 2.057 lbs a.i. per acre. California DPR, however, 

reported use of dikegulac sodium in higher amounts in recent years (2008-2012), particularly for 

landscape maintenance, where an average of 1,400 lbs a.i. were applied annually as shown m 

Table 1. 

T a bl e 1 D"k 1 egu ac s o d" mm u sem . c a rf 1 orn1a 

Sector Pounds A.I. Ap11lied Yearly 

2008 2009 2010 2011 2012 Avg. 

Rights-of-way 10 24 2 8 3 9 

Landscape 967 2.435 2,728 1,349 1,982 1,400 Maintenance 

Source: CA DPR, 2007-20 12 

BIOLOGICAL ASPECTS RELEVANT TO DIKEGULAC SODIUM 

Dikegulac sodium is a plant growth regulator registered for non-agricultural uses. It is a growth 

retardant labeled for use on many plants such as hedges, shrubs, trees and groundcovers. It is a 

DNA synthesis inhibitor labeled for greenhouses and nurseries and has high activity (USDA, 

2004). It can also be used to prevent flowering and undesired fruit set. 

ROLE OF DIKEGULAC SODIUM IN PEST MANAGEMENT 

Landscape maintenance in California is reported as the main use of dikegulac sodium in term of 

pounds a.i. applied. Other uses in California include structural control, nursery crops, and 

rights-of-way (CDPR, 2012). In North Carolina, dikegulac sodium has been recommended for 

use on landscape installation and maintenance including ornamentals as a chemical pincher to 

increase plant branching for bushy plants (USDA, 2004; USDA, 2005). It can be used to control 

growth of shrubs and to prevent fruit-set in landscapes (USDA, 2005). 

INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 

DIKEGULAC SODIUM 

The Agency currently does not have certain important information on dikegulac sodium. 

Obtaining the following information may improve future assessments conducted by the Agency 

related to the use and importance of dikegulac sodium. I. ',. 

( ' 

I 

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• Current usage information (pounds a.i. applied, average a.i. rate of application and 

number of application) on all sites. 

• Geographic distribution of dikegulac sodium use in the U.S. 

REFERENCES 

CDPR. 2012. Summary of Pesticide Use Report Data. California Department of Pesticide 

Regulation. P.O. Box 4015. Sacramento, CA 95812-4015 

USDA NASS, 2006 

USDA. 2004. Crop Profile for Ornamental Plants in North Carolina. Available at: 

http://www.ipmcenters.org/cropprofiles/docs/NCornamentals.pdf 

USDA. 2005. Crop Profile for Landscape Installation and Maintenance in North Carolina. 

Available at: http://www. ipmcenters.org/cropprofiles/docs/NC!andscape.pdf 

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