scholarly journals (93) Evaluating the Effectiveness of Prohexadione-Ca as a Plant Growth Retardant on Buddleia, Dianthus, Eupatorium, and Lilium

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1045E-1046
Author(s):  
Roberto G. Lopez ◽  
Erik S. Runkle

Prohexadione-Ca (ProCa) is a relatively new plant growth regulator (PGR) that inhibits internode length in rice, small grains, and fruit trees. However, little is known about its efficacy and potential phytotoxicity on floriculture crops and how it compares to other commercially available PGR chemicals. The effects of two foliar spray applications (2 weeks apart) of ProCa (500, 1000, or 2000 ppm), paclobutrazol (30 ppm), or a tank mix of daminozide plus chlormequat (2500 and 1000 ppm, respectively) were quantified on Dianthus barbatus L. `Interspecific Dynasty Red', Ageratina altissima R. King & H. Robinson (Eupatorium rugosum) `Chocolate', Lilium longiflorum Thunb. `Fangio', and Buddleia davidii Franch. `Mixed.' All plants were forced in a glass-glazed greenhouse with a constant temperature setpoint of 20 °C under a 16-h photoperiod. Two weeks after the second spray application of ProCa at 500, 1000, or 2000 ppm, plant height of Dianthus and Lilium was shorter than control plants by 56%, 60%, and 65% and by 6%, 26%, and 28%, respectively. However, ProCa bleached and reduced the size of Dianthus flowers. ProCa at 2000 ppm and daminozide plus chlormequat were effective at controlling the height of Eupatorium (64% and 53% reduction, respectively); however, leaves of Eupatorium were discolored and showed symptoms of phytotoxicity 1 week after the first ProCa application. Only daminozide plus chlormequat were effective on Buddleia. ProCa is an effective PGR for most of the crops we tested; however, its discoloration of red flowers and foliage may limit its application for commercial use.

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 438D-438
Author(s):  
Brian E. Whipker ◽  
Shravan Dasoju

Plant growth retardant (PGR) foliar spray treatments (mg•liter–1) of daminozide at 1000 to 16,000; paclobutrazol from 5 to 80; and uniconazole from 2 to 32 were applied to `Pacino' pot sunflowers (Helianthus annuus) to compare their effectiveness at chemical height control. When the first inflorescence opened, the number of days from seeding until flowering, total plant height measured from the pot rim to the top of the inflorescence, inflorescence diameter, and plant diameter were recorded. Total plant height, plant diameter, inflorescence diameter, and days until flowering were significant for the PGR treatment interaction. Marketable-sized plants grown in the 1.2-liter pots were produced with uniconazole concentrations between 16 and 32 mg•liter–1 or with daminozide concentrations between 4000 and 8000 mg•liter–1. Paclobutrazol foliar sprays up to 80 mg•liter–1 had little effect and higher concentrations or medium drench treatments should be considered.


HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 500C-500
Author(s):  
J.H. Lieth ◽  
L.R. Oki ◽  
P. Ng ◽  
M.C. Garcia-Navarro ◽  
S.H. Kim ◽  
...  

Daminozide is a growth retardant used in potted plant production as a foliar spray to inhibit shoot elongation. It has its greatest inhibitory effect immediately after application, becoming less pronounced thereafter; continued retardation is accomplished by reapplication at 7to 14-day intervals. A model for this retardation effect is useful in developing decision support tools, as well as in optimizing (perhaps minimizing) the use of this growth retardant. Such a model, as developed and described earlier, simulates the effect of a foliar spray application of daminozide at various concentrations on various days during the production cycle. The objective of this work was to validate this model for various varieties of chrysanthemum. Using the model to simulate the effect of one application of daminozide resulted in predicted plant heights very close to the observed heights for most of the varieties tested. Of four methods used to implement the multiple-application effect, two resulted in very good simulation of the observed plant heights. In summary, the model was shown to be valid for all the varieties of chrysanthemum tested.


HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 593B-593
Author(s):  
Joyce G. Latimer ◽  
Paul A. Thomas

Nine perennial bedding plants were screened for responsiveness to the plant growth retardant, Sumagic (uniconazole-P). Two weeks after planting, plugs were treated with one foliar spray of Sumagic at 0, 40, 80, 120, or 160 ppm at the label-recommended volume. Plant growth of Gaillardia grandiflora `Goblin' was not reduced by Sumagic. Height of Achillea × `Moonshine' was reduced 8% to 12% at 4 weeks after treatment (WAT), and the reduction persisted through 8 weeks after planting (WAP) to the landscape. Phlox paniculata `Joliet' responded linearly to increasing Sumagic rate with a maximum height reduction of 32% at 160 ppm. Coreopsis grandiflora `Sunray', Rudbeckia fulgida var. Sullivantii `Goldsturm' and Monarda didyma `Blue Stocking' responded significantly to Sumagic with 30% to 60% height reductions at 4 WAT, but no persistent effects at 8 WAP. Height of Veronica alpine `Goodness Grows' was reduced 32% to 68% at 4 WAT, but all Sumagic rates resulted in persistent reductions in plant height at 12 WAP. Plant height of Alcea rosea mix and Echinacea purpurea were excessively reduced (up to 79%) at 4 WAT, but there were no persistent effects on height of Alcea in the landscape. All rates of Sumagic resulted in persistent reductions in height of Echinacea at 8 WAP, but only plants treated with 120 and 160 ppm Sumagic were still significantly shorter than controls at 12 WAP


2000 ◽  
Vol 18 (1) ◽  
pp. 49-52
Author(s):  
Heather C. Schultz ◽  
Gary J. Keever ◽  
J. Raymond Kessler ◽  
Roland R. Dute

Abstract A study was conducted to determine the effects of benzyladenine (BA) on improving summer quality of hosta in container production and in the landscape. For container production, stock plants of Hosta ‘Sum and Substance’, H. sieboldiana ‘Elegans’, H. ‘Francee’, H. sieboldiana ‘Frances Williams’, H. plantaginea, and H. ‘Tokudama’ were divided and potted. When they showed signs of summer dormancy or foliar decline, half the plants of each cultivar/species received a single foliar spray application of 3000 ppm BA. In the landscape, half the established field-planted hosta with 27–4 initial offsets (‘Francee’) or 0–3 initial offsets (‘Frances Williams’) received a single foliar spray application of 3000 ppm BA when plants began to show signs of summer dormancy. BA stimulated the outgrowth of axillary and rhizomic buds in all cultivars/species in both parts of the study. Offsets formed more leaves on plants treated with BA compared to the untreated hosta. Offset leaf number was dependent on cultivar in both locations, and initial offset number affected leaf number for ‘Frances Williams’ in the landscape. Generally, BA application improved plant appearance of cultivars/species in both parts of the study. Cultivar/species and BA influenced whole plant growth index in container production, but had no effect in the landscape.


2015 ◽  
Vol 33 (2) ◽  
pp. 84-88
Author(s):  
Mohan Li ◽  
J. Raymond Kessler ◽  
Gary J. Keever ◽  
Wheeler G. Foshee

A study was conducted to determine the effects of bulking duration and the plant growth retardant daminozide on plant growth and flowering of greenhouse-grown ‘Coronation Gold’ yarrow (Achillea בCoronation Gold’). Single-shoot liners of yarrow were transplanted on October 14 and December 2, 2010, into 15 cm (6 in) containers and bulked for 4, 6, 8, or 10 weeks prior to exposure to night-interrupted lighting (NIL). Increasing the bulking duration increased the number of shortened, thickened stems of rosette-like appearance, or offsets, that had developed from the base of the main stem by the end of bulking by 100 to 367% and reduced days to first and five open inflorescences, hereafter referred to as flowers, from the beginning of NIL by 13 to 16 days and 10 to 20 days for the October and December potting dates, respectively. Increasing the bulking duration increased flower and flower bud number by 67 and 25% in the October 14 and December 2 potting dates, respectively. Therefore, more flowers and flower buds formed on yarrow when potted early, compared to late potting. Lengths of the first five open flower stems were inconsistent and minimally affected by bulking duration. In a repeat of the experiment potted on December 2 using the same bulking treatments, 5,000 ppm of daminozide was applied as a foliar spray when half the plants in a bulking duration had begun to elongate and was reapplied 1 week later. Daminozide application decreased stem length at first open flower by 20 to 43%, but increased days to first flower and five open flowers by 6 and 8 days, respectively. As in the first experiment, increasing the bulking duration increased the number of offsets and flower and flower bud number and reduced days to first and five open flowers.


1998 ◽  
Vol 8 (1) ◽  
pp. 86-88 ◽  
Author(s):  
Brian E. Whipker ◽  
Shravan Dasoju

Plant growth retardant (PGR) foliar sprays (in mg·L−1) of daminozide at concentrations from 1,000 to 16,000; paclobutrazol from 5 to 80; and uniconazole from 2 to 32 were applied to `Pacino' potted sunflowers (Helianthus annuus L.) to compare their effectiveness at chemical height control. Plants were grown in 650-mL or 1.2-L pots. When the first inflorescence started to shed pollen, number of days from seeding until anthesis, total plant height measured from the pot rim to the top of the inflorescence, inflorescence diameter, and plant diameter were recorded. There was no significant difference in plant height between `Pacino' plants grown in 650-mL or 1.2-L pots. Total plant height, plant diameter, inflorescence diameter, and days until flowering were significant for the PGR treatment main effect. Marketable-sized plants grown in the 1.2-L pots were produced with uniconazole concentrations from 16 to 32 mg·L−1 or with daminozide concentrations from 4,000 to 8,000 mg·L−1. Paclobutrazol foliar sprays up to 80 mg·L−1 had little effect, and higher foliar spray concentrations or substrate drench treatments may be needed to effectively control height.


2012 ◽  
Vol 22 (2) ◽  
pp. 164-168 ◽  
Author(s):  
Christopher J. Currey ◽  
Roberto G. Lopez ◽  
Brian A. Krug ◽  
Ingram McCall ◽  
Brian E. Whipker

The objective of this research was to quantify how flurprimidol substrate drenches applied to ‘Nellie White’ easter lilies (Lilium longiflorum) affected height at flowering, time to flower, and flower number. In Expt. 1, size 9/10 ‘Nellie White’ easter lilies were treated with a 4-fl oz drench applied to the surface of the substrate when shoots were ≈3 inches tall providing 0.0, 0.02, 0.04, 0.08, 0.16, or 0.24 mg flurprimidol per pot or 0.03 or 0.06 mg uniconazole per pot. In Expt. 2, size 10/12 ‘Nellie White’ easter lilies were treated with 4-fl oz drenches applied to the surface of the substrate when shoots were ≈3 inches tall providing 0.0, 0.01, 0.02, 0.04, 0.06, or 0.08 mg flurprimidol per pot. In Expt. 1, plants treated with flurprimidol or uniconazole were up to 38.9 cm (59%) shorter than untreated plants, while time to flower and flower number remained unaffected by plant growth retardant (PGR) treatments. In Expt. 2, as the amount of flurprimidol increased from 0.01 to 0.08 mg/pot, plant height was suppressed linearly (r2 = 0.63), by up to 23.2 cm (28%), while time to flower and flower number remained unaffected. Additionally, the chemical cost for drenches containing flurprimidol is less than the cost of uniconazole required to achieve comparable height control. Flurprimidol substrate drenches appear to be an effective and economical alternative to control easter lily height.


HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 432b-432
Author(s):  
Anna Perkins Nina Bassuk

Budbreak inhibition and poor overwinter survival (OS) limit successful cutting propagation of Acer rubrum October Glory, A. rubrum Red Sunset, Hamamelis vernalis, H. virginiana and Stewartia pseudocamellia. Localized blanching (banding) of the cutting on the stock plant; a range of 3 IBA concentrations, and foliar spray application of: 1% silver thiosulfate(STS), STS followed ten days later by Gibberellin, GA4/7:250ppm(STS GA),50ppm thidiazuron (TDZ) and TDZ followed by GA4/7 (TDZ GA)were tested for increasing growth and overwinter survival.. Carbohydrates were analyzed in cuttings which did and didn't grow. A. rubrum October Glory*, and Hamamelis spp all had increased OS for cuttings which grew. A. rubrum Red Sunset demonstrated a similar trend. Hamamelis spp. had significant increase in carbohydrates for cuttings which grew. A. rubrum October Glory' exhibited the same trend. S. pseudocamellia did not have increased OS with growth. and showed no increases in carbohydrates with growth, but the cuttings that didn't grow had at least 93 % more carbohydrates than the other species analyzed. All species had higher OS when stored in the 3° C cooler, than in the fluctuating cold frame. Banding increased growth of A. rubrum October Glory, and H. virginiana. IBA concentration affected growth of all species. STS increased growth of H. virginiana and S. pseudocamellia. GA4/7 increased growth of all cuttings except A. rubrum October Glory.


2000 ◽  
Vol 18 (1) ◽  
pp. 45-48
Author(s):  
Heather C. Schultz ◽  
Gary J. Keever ◽  
J. Raymond Kessler ◽  
Roland R. Dute ◽  
John W. Olive

Abstract A study was conducted to determine the effects of root mass and benzyladenine (BA) on offset formation in hosta. Stock plants of two cultivars, ‘Francee’ and ‘Frances Williams’, were divided, and offsets were placed in either small, medium, or large root mass groups. Offsets were potted and, when surface root development was evident, half of the plants in each root mass group received a foliar spray application of 3000 ppm BA, while half served as BA controls. Offset formation was positively correlated with increasing root mass, regardless of BA application. BA stimulated the outgrowth of axillary and rhizomic buds in both cultivars. Offsets on plants treated with BA were at a more advanced stage of development (SOD) than offsets on BA controls, but root mass did not affect SOD. Root mass, but not BA, affected whole plant growth index, which increased with increases in root mass.


2002 ◽  
Vol 12 (3) ◽  
pp. 426-431 ◽  
Author(s):  
Anil P. Ranwala ◽  
Garry Legnani ◽  
Mary Reitmeier ◽  
Barbara B. Stewart ◽  
William B. Miller

We evaluated preplant bulb dips in three commercial plant growth retardants [ancymidol (A-Rest), paclobutrazol (Bonzi), and uniconazole (Sumagic)] for height control in seven oriental hybrid lily (Lilium) cultivars (Aubade, Berlin, Casa Blanca, Muscadet, Sissi, Star Gazer, and Tom Pouce), and seven LA-hybrid lily [hybrids resulting from crosses between easter lily (Lilium longiflorum) and Asiatic hybrids] cultivars (Aladdin's Dazzle, Best Seller, Cebeco Dazzle, Royal Dream, Royal Parade, Royal Perfume, and Salmon Classic) grown in containers. A 1-min dip into a range of concentrations of each product was used to determine the optimum concentrations for height control. The results indicate that bulb dips, especially with uniconazole and paclobutrazol, can be a highly effective means of height control in hybrid lilies. Cultivars varied in their response to growth retardant treatments. In general, LA-hybrid lilies were much more responsive to the growth retardant treatments than oriental hybrids and required lower rates for comparable height control. Delays in flowering, increased bud abortion and leaf yellowing were observed only with high concentrations of uniconazole or paclobutrazol where the height reduction was also too excessive for a commercially acceptable crop.


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