Selecting and Using Plant Growth Regulators on Floriculture Crops

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Selecting and Using Plant Growth Regulators on
Floriculture Crops

• Guy Metzler
• Penn State Extension
• Multi-county Horticulture/Greenhouse Agent

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Why Might We Use PGRs?

• Reduce rate of growth
• Improve color, condition, toughness
• Increase plant branching, or density
• Enhance flower initiation, or synchronize
  flowering

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Read The Label

• Is the product labeled for the crop you are
  growing? (Specific, general use).
• Look for effectiveness and phytotoxic effects.
• Look at effect on flower development.

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PGRs Available for Height Control on Greenhouse
Ornamental Crops

• Sumagic (Valent)
• Fascination(Valent)
• Pro-Gibb (Valent)
• Atrimmec (Gordon PBI)
• Off-Shoot-O (Cochran)

• B-nine (Uniroyal)
• Bonzi (Syngenta)
• A-Rest (Sepro)
• Pistel (Monterey chemical)
• Cycocel (Olympic Horticulture Products)

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B-Nine (Daminozide)

• Uniroyal product
• Low phytotoxicity
• Foliar sprays only (mobile)
• Rates from 1,250 to 5,000 ppm
• Soft on plugs, large plants
• High temps a minus

• Not effective on geraniums, impatiens, pansy,
  lilies, petunias?
• Need multiple applications
• Synergistic with Cycocel
• Easy to use, may delay flowering

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Cycocel (Chlormequat)

• Olympic Hort product
• High phytotoxicity (temporary)
• Foliar, stem, root (mobile)
• Rates 1000 to 3000 ppm
• Less active under high temperatures

• Poinsettias, azaleas, geraniums, and a few others
  (research)
• Used on plugs, small plants
• Promotes flowering
• Synergistic with B-nine
• Easy to use

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A-Rest (ancymidol)

• Sepro product
• Some phytotoxicity (high temperatures,
  poinsettia)
• Leaves, stems, roots, (mobile)
• Rates 10 to 200ppm sprays. Low drench rates

• Bulb crops, baskets as drench. High value plugs.
  Wide range
• Ineffective on impatiens
• High cost
• Tank mix with B-nine?

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Bonzi (Paclobutrazol)

• Syngenta product
• Triazole (fungicide)
• Low phytotoxicity
• Root, stem, shoot absorbed. (mobile)
• Rates 2 to 90 ppm
• Low drench rates
• Light, temperature, fertility sensitive

• Pansy, vinca high sensitivity
• Snaps low sensitivity, begonia dangerously high!
• Use 1to 2 times, alone
• A bit harder to use
• Effects flower size, leaf size

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Sumagic (Uniconazole)

• Valent product
• Triazole (fungicide)
• Low phytotoxicity
• Root, stem, shoot absorbed (mobile)
• Rates 1 to 50 ppm
• Least sensitive to environment factors

• Pansy, geranium, vinca, sensitive
• Dangerous on begonia and plugs.
• Mostly 1 application, alone
• Can be hard to use
• Watch over-spray

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Atrimmec (Dikegulac-sodium)

• PBI Gordon product
• Phytoxicity high(tips yellow)
• Foliar (mobile)
• 2 to 30 ml/liter
• 18.5 active ingredient
• Chemical pinching agent

• Best on woody plants but begonia, fuchsia, ivy
  geranium, kalanchoe, and verbena labeled
• 1 application
• Greenhouse nursery and landscape application

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Pistel (Ethephon)

• Monterey chemical
• Low phytotoxicity
• Foliar absorbed
• Rates 300 to 500 ppm
• Need low pH water
• Lateral branching, shortened internodes, removes
  flower initiation

• All crops to some degree
• Needs multiple applications
• Cheap
• No tank mixes
• Easy to use
• Need research on vegetable transplants

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Other Specialty PGRs

• Off shoot O (Cochran chemical) Azaleas chemical
  pinch
• Fascination ( Valent) lilies, bulbs
• Topflor ( Sepro)
• general bedding?, potted crops?