Selecting and Using Plant Growth Regulators on floricultural Crops

Selecting and Using Plant Growth Regulators on Floricultural Crops

Authors: Joyce G. Latimer, Extension Specialist, Greenhouse Crops; Virginia Tech

Publication Number 430-102, November 2001

Table 2 Other plant growth regulators used in the production of floricultural crops.

Trade name/Common Name Application methods Comments Concerns

Florel® Brand Pistill ethephon
Monterey Chemical Co.
Foliar spray Promotes lateral branching, thereby reducing stem elongation. Also aborts flowers; improves stock plant branching and cutting yield. Use early in crop cycle to increase branching and remove early flowers (6-8 wk before flowering). Induces flowering of bromeliads. Reduces height and stem topple of potted daffodils and hyacinths. New broad use label approved by EPA. The pH of spray solution should be below 5.0. Has no drench activity. Use within 4 hours of mixing. Results less predictable under high temperature conditions. Do not treat plants under environmental stress conditions.

Atrimmec dikegulac sodium
PBI Gordon
Foliar spray Inhibits terminal growth, thereby promoting lateral development. Apply to actively growing plants with at least two nodes to provide sufficient lateral development. May significantly delay plant development, especially at higher rates. Causes leaf chlorosis which may be presistent at high rates.

Fascination benzyladenine/GA₄₊₇
Valent USA
Foliar spray Growth promoter. Labeled for prevention of leaf yellowing and to delay flower senescence of Easter, oriental and Lilium longiflorum x asiatic (LA) hybrid lilies. Effective dose strongly affected by volume (soil active). Thorough coverage required. Avoid application to plants under conditions of environmental stress.

Off-Shoot-O gibberellic acid
Agtrol International
Foliar spray Labeled for chemical pinching of actively growing azalea, contoneaster, jiniper, ligustrum, Rhamnus, and Taxus. Ensure coverage of growing points.

GibGro gibberellic acid
Agtrol International
Foliar spray Growth promoter. Labeled for: substitution of cold to force flowering azaleas; to inhibit flower buds on vegetative azaleas; peduncle elongation of pompom mums; earlier flowering and increased yield of statice; induction of flowering of spathiphllym. Do not spray more than once. Over application or incorrect timing can cause weak stems and exessive stem elongation.

Trade name/Common Name	Application methods	Comments	Concerns
Florel® Brand Pistill ethephon Monterey Chemical Co.	Foliar spray	Promotes lateral branching, thereby reducing stem elongation. Also aborts flowers; improves stock plant branching and cutting yield. Use early in crop cycle to increase branching and remove early flowers (6-8 wk before flowering). Induces flowering of bromeliads. Reduces height and stem topple of potted daffodils and hyacinths.	New broad use label approved by EPA. The pH of spray solution should be below 5.0. Has no drench activity. Use within 4 hours of mixing. Results less predictable under high temperature conditions. Do not treat plants under environmental stress conditions.
Atrimmec dikegulac sodium PBI Gordon	Foliar spray	Inhibits terminal growth, thereby promoting lateral development. Apply to actively growing plants with at least two nodes to provide sufficient lateral development.	May significantly delay plant development, especially at higher rates. Causes leaf chlorosis which may be presistent at high rates.
Fascination benzyladenine/GA₄₊₇ Valent USA	Foliar spray	Growth promoter. Labeled for prevention of leaf yellowing and to delay flower senescence of Easter, oriental and Lilium longiflorum x asiatic (LA) hybrid lilies.	Effective dose strongly affected by volume (soil active). Thorough coverage required. Avoid application to plants under conditions of environmental stress.
Off-Shoot-O gibberellic acid Agtrol International	Foliar spray	Labeled for chemical pinching of actively growing azalea, contoneaster, jiniper, ligustrum, Rhamnus, and Taxus.	Ensure coverage of growing points.
GibGro gibberellic acid Agtrol International	Foliar spray	Growth promoter. Labeled for: substitution of cold to force flowering azaleas; to inhibit flower buds on vegetative azaleas; peduncle elongation of pompom mums; earlier flowering and increased yield of statice; induction of flowering of spathiphllym.	Do not spray more than once. Over application or incorrect timing can cause weak stems and exessive stem elongation.

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