UNITED ST ATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

DEC 2 2 2015 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Uniconazole (128976) 

FROM: 

THRU: 

TO: 

Leonard Y ourman, Plant Pathologist I j 

Biological Analysis Branch /V~ 

Don Atwood, Entomologist 

Science Information and Analysis Branch 

Andrew Lee, Economist {). j C h 

Economic Analysis Branch 'tf 

Biological and Economic Analysis Division (750 '-";.._.,-~ 

Mark Suarez, Acting Chief 

Biological Analysis Branch 

Diann Sims, Chief 

U\ 

,JYY'rl#~~ Science Information and Analysis Branch 

Timothy Kiely, Chief ·AA ' \) 

Economic Analysis Branch v- \. ~ Biological and Economic Analysis ·vision (7503P) 

Susan Bartow, Chemical Review Manager 

Risk Management and Implementation Branch l V 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel: December 9, 2015 

SUMMARY 

Uniconazole is a growth regulator that is used on herbaceous ornan1ental plants to reduce shoot 

and stem elongation to provide consumers with compact and uniform transplants for placement 

in plant beds, gardens, and other ornamental locations. Similarly, uniconazole is registered for 

use on fruiting vegetable transplants to produce compact tomatoes, peppers, and eggplant for sale 

to consumers. It can be used as a fol iar spray, bulb dip or substrate drench (Currey and Lopez, 

20 I 0). Uniconazole is a triazole chemical related to the more widely used plant growth 
regulator, paclobutrazol. Uniconazole, like paclobutrazol. inhibits gibberellic acid synthesis and 

thus reduces seed germination and stem and shoot elongation (Arnold and McDonald, 2001). 

Uniconazole is effecti ve on a wide range of ornamental species. which is one of the reasons it 

has been important fo r propagators of various plant species. According to publicly available data 

(NASS, 2007) uniconazole is used to varying degrees in the nursery propagation industry; use 

appears to vary according to the crop grown and location of the nursery. For example, a large 

number of Texas woody ornamental & vine operations use both uniconazole and paclobutrazol, 

while paclobutrazoL not uniconazole, is used widely by Texas nursery propagation operations. 

In general, while paclobutrazol appears to be more widely used than uniconazole. uniconazole 

provides plant propagators with a highly active growth regulator that results in compact and 

uniform transplants characteristics that are necessary for marketability and consumer acceptance. 

INTRODUCTION 

FIFRA Section 3(g) mandates that EPA periodically review the registrations of all pesticides to 

insure that they do not pose unreasonable adverse effects to human health and the environment. 

This periodic review is necessary in light of scientific advancements. changes in policy, and 

changes in use patterns that may alter the conditions underpinning previous registration 

decisions. ln determining whether effects are unreasonable. FIFRA requires that the Agency 

consider the risks and benefits of any use of the pesticide. 

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

brief overview of the pest management roles for uniconazole. However. BEAD does not have 

current usage data for uniconazole and does not have a label data report. The information 

provided in this BEAD Chemical Profile (BCP) may be used by stakeholders (e.g., users and 

registrants). OPP risk and benefit assessors, and OPP risk managers. and the general public 

during the Registration Review process of this pesticide. 

AGRICULTURAL USE SITES 

Uniconazole can be used for production of fruiting vegetable transplants including tomato, 

pepper, and eggplant in greenhouses, shadehouses, or lathhouses. This use results in more 

compact transplants that result in high density production plantings and more marketable 

transplants to consumers. 

NON-AG RI CULTURAL USE SITES 

Use sites are ornamental plants grown in commercial greenhouses. glasshouses, lathhouses, and 

shade structures (where plants are grown in containers). Listed plants include annual and 

perennial bedding plants. bulbs (dip), woody landscape ornamentals. Easter lily, Poinsenia, and 

others. 

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FORMULATIONS AND APPLICATION METHODS 

Uniconazole may be applied to plant shoots or roots as foliar sprays, substrate drenches, liner 

dips, and media sprays (Currey and Lopez, 2010). Foliar sprays are the most common but spray 

volume (to runoff) can vary among applicators compromising uniformity. One strategy has been 

the application of a specific volume per area (e.g., Currey and Lopez, 20 I 0- two quarts spray 

solution per 100 sq ft). 

HISTORY OF BEAD ASSESSMENTS 

A search of the BEAD database indicates that BEAD has not conducted benefits or impact 

assessments for uniconazole. In 2007, BEAD reviewed a Section 18 Emergency Exemption 

request for use of this chemical on transplant tomatoes in greenhouses to control excessive 

growth. BEAD determined that the situation appeared to be a chronic problem rather than an 

emergency. However, the need for a material to produce more marketable compact plants is 

exemplified by the subsequent Section 3 labeling of uniconazole for use in the production of 

fruiting vegetable transplants. 

USAGE 

Uniconazole is effective on a wide variety of plant species. Use rates depend on the ornamental 

species of interest. For growth control, some bedding plants may receive a single spray of 1-2 

ppm, while more aggressive plants (e.g., petunia or marigold) may require higher rates (4-6 ppm) 

(Runkle, 2011). Fast growing perennials such as gaura, liatris, and phlox may require rates of 

10-15 ppm. These rates (for Michigan) may be lower than rates necessary in warmer locations. 

Depending on the plant and use rates, the reduction of stem elongation may last for 3-5 weeks or 

longer. Uniconazole is absorbed most effectively by the plant stem. Application timing is 

critical and application is typically 7-10 days after transplant of plugs and cuttings. The effect on 

stem elongation is usually observed seven to ten days after application (Runkle, 2011 ). 

According to NASS data (NASS, 2007) use rates may range from approximately 0.00 I to 0.044 

lb per acre (for bedding plants), with an average of 0.01 lb per acre for all nursery operations. 

Table 1 summarizes NASS data that provides the percent of nursery operations that use 

uniconazole. For comparison, data for the similar and most widely used growth regulator, 

paclobutrazol, is also provided. Only a few (program) states were indicated in the summary and 

therefore, nursery use nationwide may not be accurately reflected. Data were not available for 

all nursery operations. Nevertheless, the data indicate a wide range of use by nursery 

operators- a large number of Texas woody ornamental & vine operations use both uniconazole 

and paclobutrazol, while paclobutrazol, not uniconazole, is used widely by Texas nursery 

propagation operations. In general, paclobutrazol appears to be more widely used than 

uniconazole. 

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Table 1. Summary1 of Percent of Nursery Operations Using Uniconazole and Paclobutrazol 

(2006) 

Pro!!ram States 

CA I FL Ml I OR 1 PA 1 TX 1 

I I I I I 

Percent of All Nursery & Floriculture Operations Using A.I. 

Uniconazole 4 I -- 8 I I I 2 I 5 I 

Paclobutrazol 8 I -- 18 I I -r 10 I 6 I 

Percent of All Nursery Operations Using A.I. 

Uniconazole I I -- -- I -- I -- I 8 I 

Paclobutrazol 2 I I I I -- l -- -, 8 I 

Percent of Nursery Propagation Operations Using A.I. 

Uniconazole 3 I -- -- I -- I -- l 5 l 

Paclobutrazol 6 I -- -- I -- l -- 1 51 -, 

Percent of Deciduous Shrub Operations Using A.I. 

Uniconazole -- I -- -- I -- I -- I 44 I 

Paclobutrazol -- I -- -- I -- l -- l -- -, 

Percent of Other Woody Ornamental & Vine Operations Using A.I. 

Uniconazole -- I I -- I -- I 9 l 47 l 

Paclobutrazol 6 I 4 -- I -- I -- I 47 I 

Percent of All Floriculture Ooerations Using A.I. 

Uniconazole 5 I -- 16 I .., 

-' I .., -' I 10 I 

Paclobutrazol II I 2 34 I 6 I 21 l II -, 

Percent of Flowering Plant Operations Using A.I. 

Uniconazole 7 I 2 10 I 4 I 4 I 13 I 

Paclobutrazol 11 I 7 17 I 12 I 23 I 15 I 

Percent of Bedding Plant Operations Using A.I. 

Uniconazole 16 I -- 19 I 5 I 2 l 11 l 

Paclobutrazol 30 I 19 39 I 9 I 20 I 11 I 

Percent of Foliage Ooerations Using A.I. 

Uniconazole 2 I -- 14 I -- I -- I -- I 

Paclobutrazol 2 I ..,.., -- I I 5 1 2 l -'-' -- Percent of Floriculture Operations Using A.I. 

Uniconazole -- I -- 10 I -- I -- I -- I 

Paclobutrazol 12 I 18 10 I -- I 10 I -- l 

Percent of Herbaceous Perennial Operations Using A.I. 

Uniconazole 5 I -- 9 I 3 I -- -, -- I 

Paclobutrazol 5 I -- 14 I 3 I 8 I 2 I 1 Agricultural Chemical Usage 2006 Nursery and Floriculture Summary. December 2007. USDA National 

Agricultural Statistics Service (NASS). 

Total 

.., 

-' 

7 

I 

I 

I 

9 

8 

--

5 

8 

6 

14 

7 

15 

II 

24 

1 

2 

2 

7 

2 

6 

http://usda. mannl ib.comel l.edu/usda/nass/ AgriChem UsN ursFlo//2000s/2007 I AgriChem UsNursFlo- 12-19-2007 .pdf 

(--)Indicates that the infom1ation was not published by NASS. 

ROLE OF UNICONAZOLE 

Uniconazole is a growth regulator that can be used as a foliar spray, bulb dip or substrate drench 

(Currey and Lopez, 2010). It is a triazole chemical related to the most wide ly used plant growth 

regulator, paclobutrazol, but up to five times more active on a ppm basis. Uniconazole can be 

applied as a drench at rates 50% lower than those used for paclobutrazol (Whipker, 2013). 

Uniconazole, like paclobutrazol, inhibits gibberellic acid synthesis and thus reduces stem and 

shoot elongation (Arnold and McDonald, 2001). Uniconazole does not readily move within the 

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plant since they are transported in the xylem and not the phloem (Whipker. 2013). As a result 

uniconazole (as well as paclobutrazol) is absorbed by the leaves, but is not readily transported 

out to other parts of the plant. Uniconazole is typically used on a wide range of herbaceous 

ornamental plants to reduce plant height, which is important in order to provide compact and 

uniform plants with optimal aesthetic appeal to the end-user. In addition, a secondary effect of 

uniconazole (and other gibberellic acid regulators) is an increase in chlorophyll production 

creating greener leaves (Whipker, 2013). These attributes indicate benefits for both the grower 

and consumer. It is among the most active and persistent plant growth regulators. Rates are 

determined by the type of plant and the length of time that the growth reduction effect is desired. 

Excessive persistence of the growth regulator is not considered desirable once the plant is sold to 

the consumer (Latimer et al.. 2003). 

INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK 

If risks are identified for uniconazole a benefits or impact assessment may be necessary to weigh 

risk and benefits. BEAD data presented in this memo were obtained from a publicly available 

survey that was conducted in 2006 (NASS, 2007). Therefore, updated information on the use of 

uniconazole would be necessary to indicate its role in nursery and transplant management. In 

addition, the relative importance of uniconazole (in comparison with widely used alternatives. 

such as paclobutrazol) will enable an assessment of the value and benefits of uniconazole to 

growers and consumers. 

REFERENCES 

Arnold, M.A. and McDonald, G. V. 2001. Paclobutrazol and uniconazole applications affect 

production quality and subsequent landscape performance of blue Plumbago. 

http://wv.rw.plantanswers.com/research blue plumbago.htm 

Currey, C. J. and Lopez. R. G. 20 l 0. Applying plant growth retardants for height control. 

Commercial Greenhouse and Nursery Production. Purdue University Extension Pub!. H0-248-

W. https://www.extension.purdue.edu/extmedia/HO/H0-248-W.pdf 

EPA 2007. Office of Pesticide Programs. Biological and Economic Analysis Division. "Review 

of a Request for Emergency Exemption of Uniconazole-p in Alabama for Use on Transplant 

Tomatoes in Greenhouses to Control Excessive Growth. (07-AL-0 1) (D335047). 

Latimer, J. G., Scoggins, H. L., and Banko, T. J. 2003. Persistence of plant growth regulator 

effects on perennial plants in the nursery. Proc. XXVl International Horticultural Congress 

(IHC), Acta Hort. 624: 229-232. 

http://www.hort.vt.edu/lloriculturc/documents/VT 2003 Persistence of Plant Growth Regulat 

or Effects on Perennial Plants in the Nursery Acta! 1011 624 p229 232.pdf 

NASS. 2007. Nursery and Floriculture Chemical Usage Data, 2006. USDA National Agricultural 

Statistics Service (NASS). December 2007. 

5 
http://usda.mannlib.cornell.edu/usda/nass/AgriChemUsNursFlo//2000s/2007/AgriChemUsNursF 

lo-12-19-2007 .pdf 

Runkle, E. 2011 . Tips on using uniconazole. Greenhouse Product News. April 13, 2011. 

http://v.'WW.gpnmag.com/tips-using-uniconazole 

Whipker, B. E. 2013. Plant growth regulator guide. Grower Talks Magazine. 

http://www.ballpublishing.com/pdf/PGR GUIDE 2013-LowRcz.pdf 

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