UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAY 192015 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

Qualitative Assessment of Daminozide Use in Ornamental Plant Production (DP# 

426348) (PC Code 03510 I) 

Sunil Ratnayake, Biologist, ( 1~,

1 Biological Analysis Branch 

~ 

Stephen Smearman, Economist J..J- _J. A . J ...... 

Economic 

Biological 

Analysis 

and Economic 

Branch 

Analysi

~ 

s Division 

~ 

(7503P) 

Arnet Jones, Chief ~ ~ 

Biological Analysis Branc ~ . 

Timothy 

Economic 

Kiely, 

Analysis 

Chief 

Branch 

n 

'\J J ~ 

Biological and Economic Analysis Division (75 ) 

Margaret Hathaway, Chemical Review Manager 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: April 15, 2015 

SUMMARY 

Daminozide is a systemic plant growth regulator (PGR) registered in 1963 for use in ornamental 

plant production. (USEP A, 1993). Daminozide is used mostly on containerized ornamental 

plants grown in commercial or research greenhouses and nurseries. Application of daminozide 

inhibits the synthesis of gibberellic acid in plants. Acti vity of daminozide shortens the internode 

length of ornamental plants, reduces plant height, and gives a short and compact appearance. 

Currently, there are no registered food uses. 

Page I 
INTRODUCTION 

As a part of the registration review process, this brief benefits overview provides information 

needed for risk management. In particular, it considers the risks and benefits of the use of 

daminozide. 

USE SITES 

Currently, daminozide is registered for use in nurseries, shadehouses, and greenhouses. 

APPLICATION OF DAMINOZIDE 

Daminozide is applied as a spray on the fo liage of ornamental plants grown in commercial or 

research greenhouses and nurseries. It is also applied as a drench (application of the solution to 

growing substrate). Spraying is directed at the leaves and stems to the point of run-off or until 

leaves look saturated. Application rates are dependent on the crop being treated and desired 

level of plant size. Generally, daminozide is applied inside of greenhouses, so there is little or no 

potential for off-site drift. Daminozide reduces the internode length of ornamental plants by 

inhibiting the synthesis of gibberellic acid. 

BENEFITS OF USING DAMINOZIDE 

Controlling plant size is an important aspect of greenhouse plant production. Daminozide has a 

particular niche use on ornamental plants which is for reducing plant size. Reduction of plant 

size maximizes production of ornamental plants per unit area of a greenhouse. Also, it improves 

the efficiency of certain greenhouse activities such as irrigation, fertilization, and handling. In 

addition, the reduction of interrnodal length minimizes plant damage during shipping and 

handling and helps to produce more visually pleasing compact plants with deeper green 

coloration. 

Compared to the many other plant growth regulators, daminozide has a fairly short residual 

effect, typically lasting one to four weeks depending on the application rate and the 

environmental conditions. This short duration of residual activity may be desirable for young 

plant production, since the growth inhibition may be not be desirable after transplanting (Runk le, 

20 13). 

REFERENCES 

Runkle, E. 2013. Successfol Use of the PGR Daminozide. Greenhouse Product News. Online 

Publication. Available at: http://www.gpnmag.com/successful-usc-pgr-daminozide. 

Accessed on April 3, 2015. 

USEPA. 1993. Registration Eligibility Decision. Daminozide. Online Publication. Available at: 

http://www.cpa.gov/oppOOOO l /chem search/reg actions/reregistration/red PC035101 l-Sep-93.pdf. Accessed on April 3, 2015. 

Page 2