Residual Efficacy of Uniconazole and Daminozide on Potted `Bright Golden Anne' Chrysanthemum

Tayama, Harry K.; Carver, Stephen A.

doi:10.21273/hortsci.27.2.124

Cited by 4 publications

(5 citation statements)

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“…Inhibition of stem elongation in herbaceous plants such as Chrysanthemum, Poinsettia, and annual bedding plants persists for only a few weeks after application of growth retardant. Stem elongation of Chrysanthemum gradually returned to control growth rates about 15 days after the application of ancymidol (Fisher et al 1996) or daminozide or uniconazole (Tayama and Carver 1992). The duration of the growth-retarding effect was roughly proportional to the concentration of regulator applied initially (Fisher et al 1996).…”

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confidence: 98%

“…Because paclobutrazol and uniconazole have much greater dose-response coefficients, K c , than daminozide (Davis et al 1988), these triazole growth regulators can easily be applied at doses exceeding the range for linear response of stem elongation. This may explain why the effects of uniconazole lasted longer than those of daminozide in Chrysanthemum (Tayama and Carver 1992). Eight weeks after treatment, the height of bedding plants was reduced by high concentrations but not by low concentrations of uniconazole, whereas daminozide had no effect (Keever and Foster 1991).…”

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Persistence of Triazole Growth Retardants on Stem Elongation of Rhododendron and Kalmia

Gent

1997

J Plant Growth Regul

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Triazole growth retardant chemicals may inhibit stem elongation of woody ornamental species for several years after application. Potted plants of large-leaf Rhododendron catawbiense and Kalmia latifolia were treated with a single spray application of paclobutrazol or uniconazole in the 2nd year from propagation. They were transplanted into the field the next spring. The elongation of stems was measured in the year of application and in the next 2-4 years. Treatments with a wide range of doses were applied in 1991, 1992, or 1995. For all except the most dilute applications, stem elongation was retarded in the year after application. At the highest doses, stem growth was inhibited for 2 years after application. The results were fit to a model of growth regulator action which assumed that stem elongation was inversely related to the amount of growth regulator applied. For paclobutrazol, the dose per plant that inhibited stem elongation half as much as a saturating dose was tenfold that for uniconazole, about 0.5 and 0.05 mg, respectively. For both chemicals, the dose-response coefficient decreased exponentially with time after application, with an exponential time constant of about 2 year −1 . A dose of growth regulator which reduced stem elongation by half immediately after application would only inhibit 12% of stem elongation the next year. However, a tenfold greater dose would result in less than half the stem elongation of untreated plants in the next year.K e y W o r d s . G r o w t h r e t a r d a n t s -K a l m i aPaclobutrazol-Rhododendron-Stem elongationUniconazole

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confidence: 98%

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confidence: 99%

Persistence of Triazole Growth Retardants on Stem Elongation of Rhododendron and Kalmia

Gent

1997

J Plant Growth Regul

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“…Paclobutrazol had a persistent effect on stem elongation of rhododendron, in contrast to the recovery of growth of herbaceous plants. The latter generally grow out of the effect of an application of growth retardant in 4 to 6 weeks (Fisher et al, 1996;Keever and Foster, 1994;Latimer and Baden, 1992;Tayama and Carver, 1992). The response of rhododendron to a high dose of paclobutrazol decreases more slowly with time, over a period of years (Gent, 1997; Ranney et al, 1994;Wilkinson and Richards, 1992).…”

Section: Discussionmentioning

confidence: 99%

“…The time for growth to recover to the rate of controls was proportional to growth retardant concentration. A similar time period was noted for recovery of growth of chrysanthemum from either a spray or drench application of uniconazole (Tayama and Carver, 1992). To estimate the recovery of growth of rhododendron after application of triazoles, an exponential decay with time was incorporated into the coeffi cient for the inverse relation of stem elongation to initial concentration of growth retardant (Gent 1997).…”

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confidence: 93%

Efficacy and Persistence of Paclobutrazol Applied to Rooted Cuttings of Rhododendron Before Transplant

Gent¹

2004

HortSci

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Effi cacy of paclobutrazol was determined when applied to rooted cuttings before transplant. Cuttings of large-leaf Rhododendron catawbiense Michx. were treated with paclobutrazol applied as a 40-mL drench. In 1998, concentrations of 0, 1, 2, 10, or 20 mg·L -1 were applied to liners before root development was complete in February, or after cuttings were root-bound in May. The same volume of solution was applied to other plants at concentrations of 0, 5, 10, or 20 mg·L -1 in July 1998, after transplant to 1-gal pots. In 1999, a 40-mL drench of paclobutrazol at 0, 1, 2, 5, 10, or 20 mg·L -1 was only applied to liners in April. All cuttings were transplanted to 1-gal pots and set in the fi eld. The elongation of stems was measured after each of three fl ushes of growth. Plants were far more responsive to paclobutrazol when it was applied before, rather than after transplant. There was a saturating response to paclobutrazol concentration and the half-maximal response occurred at 2 to 4 mg·L -1 (0.08 to 0.16 mg/plant). At low rates, later fl ushes of growth were affected less than earlier fl ushes. However if paclobutrazol was applied at 10 or 20 mg·L -1 , later fl ushes of growth were inhibited more completely than early fl ushes. Flowering was enhanced by paclobutrazol. Paclobutrazol at 2 mg·L -1 applied to rooted cuttings before transplant was suffi cient to inhibit growth of rhododendron, but not to the point where later fl ushes of growth were excessively short. Chemical name used: 2RS,3RS-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl)-pentan-3-ol (paclobutrazol).

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“…The most appropriate form of g(t) is likely to vary depending on chemical type, translocation pathway, and plant species. Either Larsen and Lieth (1993) g(t) model may be appropriate for daminozide on chrysanthemum, because translocation and activity are rapid (Dicks, 1972) and the effect declines over time (Dicks, 1972;Dicks and Charles-Edwards, 1973;Tayama and Carver, 1992).…”

Section: Discussionmentioning

confidence: 99%

Modeling the Stem Elongation Response of Poinsettia to Chlormequat

Fisher¹,

Heins²,

Lieth³

1996

jashs

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Stem elongation response to a single foliar application of the growth retardant chlormequat chloride [(2-chloroethyl) trimethylammonium chloride] for poinsettia (Euphorbia pulcherrima Klotz.) was quantified. Growth retardant applications did not affect final leaf count or timing of visible bud, first bract color, or anthesis. There was a statistically significant effect of growth retardant concentration on stem elongation, with a range from 289 ± 15 mm (mean 95% confidence intervals) for the control plants to 236 ± 17 mm at 4000 ppm. The growth-retarding effect during the first day after the application was not significantly different between 500 and 4000 ppm, and concentration primarily affected the duration of growth-retarding activity. A dose response function was incorporated into a three-phase mathematical function of stem elongation of single-stem poinsettia to predict elongation of treated and untreated plants. The model was calibrated using a data set from plants receiving 0, 500, 1000, 1500, 2000, 3000, and 4000 ppm, with a resulting R2 of 0.99. Validation of the dose response model against an independent data set resulted in an r2 of 0.99, and predicted final stem length was within 12 mm of observed final length.

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Residual Efficacy of Uniconazole and Daminozide on Potted `Bright Golden Anne' Chrysanthemum

Cited by 4 publications

References 1 publication

Persistence of Triazole Growth Retardants on Stem Elongation of Rhododendron and Kalmia

Persistence of Triazole Growth Retardants on Stem Elongation of Rhododendron and Kalmia

Efficacy and Persistence of Paclobutrazol Applied to Rooted Cuttings of Rhododendron Before Transplant

Modeling the Stem Elongation Response of Poinsettia to Chlormequat

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