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Plant Growth Regulators1
Frederick M. Fishel2This document discusses the meaning of the term "plant growth regulator," patterns of use and provides a listing of plant growth regulators registered for use in Florida.
Introduction: what are plant growth regulators?
Simply put, plant growth regulators (also known as growth regulators or plant hormones) are chemicals used to alter the growth of a plant or plant part. Hormones are substances naturally produced by plants; they control normal plant functions, such as root growth, fruit set and drop, growth and other development processes. Legally, they are regulated as pesticides under the Florida Department of Agriculture and Consumer Services (FDACS) and must be registered for use as would any pesticide within the state.
FDACS Definition of "Plant Regulator"
Any substance or mixture of substances intended, through physiological action, for accelerating or retarding the rate of growth or maturation, or for otherwise altering the behavior, of ornamental or crop plants or the produce thereof; but does not include substances intended as plant nutrients, trace elements, nutritional chemicals, plant inoculants, or soil amendments.The use of plant growth regulators in agricultural production within the United States began during the 1930s. The first discovery and use was with acetylene and ethylene, which enhanced flower production in pineapple. Subsequently, their use has grown exponentially and they are major components of agricultural commodity production. Although not true plant growth regulators, certain herbicides and insecticides cause some plant growth-regulating effects. For example, the widely used insecticide, carbaryl is used to thin apple fruit from trees and to aid in encouraging annual bearing. There are six major classes of plant growth regulators according to the American Society for Horticultural Science. Table 1 lists these classes with the development function(s) and examples of practical uses which they are associated with. Table 2 provides more Florida-specific information regarding plant growth regulators registered in this state. Major commodities associated with their use, their primary function(s) and examples of trade names are included in the table.
Additional Information
American Society for Horticultural Science: http://www.ashs.org/Table 1. Plant growth regulator class, associated function(s) and practical uses.
Class
Function(s)
Practical uses
Auxins
Shoot elongation
Thin tree fruit, increase rooting and flower formation
Gibberellins
Stimulate cell division and elongation
Increase stalk length, increase flower and fruit size
Cytokinins
Stimulate cell division
Prolonging storage life of flowers and vegetables, bud initiation and root growth
Ethylene generators
Ripening
Induce uniform ripening in fruit and vegetables
Growth inhibitors
Stops growth
Promote flower production by shortening internodes
Growth retardants
Slows growth
Retard tobacco sucker growth
Table 2. Plant growth regulators registered for use in Florida.
Active ingredient
Registered crops and functions
Trade names*
Ancymidol
Ornamental plants - growth inhibitor
A-Rest®
Butralin
Tobacco - shoot inhibitor
Butralin®
C8 - C10 fatty alcohols
Tobacco - shoot inhibitor
Fair®, Royaltac®, Sucker-Plucker®, Off-Shoot®, Contact-85®
Chlormequat chloride
Ornamental flowers - shoot inhibitor
Cycocel®
Daminozide
Ornamental plants - growth inhibitor
B-Nine®
Ethephon
Turfgrass - reduces mowing frequency Various fruits, vegetables, and nuts - hastens ripening and maturity, enhance fruit color and floral stimulant
Cucurbits - increases flowering
Ground covers - inhibits flowering
Ornamental trees - inhibits fruiting
Tobacco and cotton - hastens maturity
Cereal grains and grasses grown for seed - reduces lodging
Proxy®, Ethrel®, Florel®, Mature®, Prep®, Cerone®
Fluprimidol
Ornamental woody plants and ground covers - reduces pruning Turfgrass - reduces mowing frequentcy
Cutless®
Gibberellic acid
Small fruits, cucurbits - increase fruit set Citrus - promote rind/peel integrity, prevent fruit drop
Rice, cotton - growth enhancer
GibGro®
Gibberellin mixtures
Cut flowers - plant preservative Tree fruit - increase fruit size, hasten maturity, shoot stimulant
Evergreen trees - floral stimulant, stimulate germination
BVB®, Fascination®, Procone®
Maleic hydrazide
Tobacco - shoot inhibitor Stored bulbs - sprout inhibitor
Sucker Stuff®, Royal®, Fair®
Mefluidide
Ground covers, shrubs, ornamental trees - reduces pruning Turfgrass - reduces mowing frequency
Embark®
Mepiquat chloride
Cotton - growth inhibitor, enhance uniform fruit maturity
Pix®
Mepiquat pentaborate
Cotton - growth inhibitor, enhance uniform fruit maturity
Pentia®
NAD
Woody ornamental cuttings - rooting stimulant
Rootone®
Naphthalene-acetic acid (NAA)
Ornamental plants - stimulates rooting, increase vegetative growth
Dipn Grow®, Hi-Yield®
n-Decanol
Tobacco - shoot inhibitor
Antac®, FST-7®, Royaltac®
Paclobutrazol
Ornamental plants - reduces internodal length Ornamental trees - growth inhibitor
Turfgrass - increased plant thickness, growth inhibitor
Bonzi®, Cambistat®, Profile®, Piccolo®
Prohexadione calcium
Peanut - reduce excessive vine growth Tree fruit - reduce tree canopy volume
Turfgrass grown for seed - increase seed set
Apogee®
Trinexapac-ethyl
Turfgrass - reduces mowing frequency
Primo®
Uniconazole
Ornamental plants - growth inhibitor
Sumagic®
*Consult individual labels for specific sites and commodities approved for use.
Footnotes
1. This document is PI-102, one of a series of the Pesticide Information Office, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date February 2006. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.2. Frederick M. Fishel, associate professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
Copyright Information
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.