Douglas A. Bailey’s research while affiliated with University of Arizona and other places

Plants of Euphorbia pulcherrima Wind. `Glory' were grown under total irradiances of 13.4, 8.5, or 4.0 mol·m ⁻² ·day ⁻¹ and sprayed with water (control), 2500 mg daminozide/liter + 1500 mg chlormequat chloride/liter (D + C), 62.5 mg paclobutrazol/liter, or 4, 8, 12, or 16 mg uniconazole/liter to ascertain plant developmental and postproduction responses to treatment combinations. Anthesis was delayed for plants grown under the lowest irradiance. Anthesis was delayed by the D + C treatment, whereas other growth retardant treatments had no effect on anthesis date. Irradiance did not affect plant height at anthesis, but all growth retardant treatments decreased height over control plants. Inflorescence and bract canopy diameters were decreased at the lowest irradiance level. Growth retardants did not affect individual inflorescence diameters, but all, except paclobutrazol and 4 and 8 mg uniconazole/liter, reduced bract canopy diameter compared with control plants. Plants grown under the lowest irradiance developed fewer inflorescences per plant and fewer cyathia per inflorescence. Cyathia abscission during a 30-day postanthesis evaluation increased as irradiance was decreased; cyathia abscission was unaffected by growth retardant treatment. Leaf abscission after 30 days postanthesis was lowest for plants grown under the lowest irradiance. At 30 days postanthesis, all growth retardant treatments increased leaf abscission over controls. Results indicate that irradiance and growth retardant treatments during production can affect poinsettia crop timing, plant quality at maturity, and subsequent postproduction performance. Chemical names used: 2-chloroethyl-N,N,N-trimethylammonium chloride (chlormequat chloride); butanedioic acid mono (2,2-dimethyl hydrazide) (daminozide); β-[(4-chlorophenyl) methyl]- α -(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol), (E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-l-penten-3-ol (uniconazole, XE-1019).

Plants of Euphorbia pulcherrima Wind. `Glory' were grown under 13.4, 8.5, or 4.0 mol·m ⁻² ·day ⁻¹ and sprayed with water (control); 2500 mg·liter ⁻¹ daminozide + 1500 mg·liter ⁻¹ chlormequat chloride (D+C); 62.5 mg·liter ⁻¹ paclobutrazol; or 4, 8, 12 or 16 mg·liter ⁻¹ uniconazole to ascertain plant developmental and pest-production responses to the treatment combinations. Days to anthesis increased as irradiance was decreased. Anthesis was delayed by the D+C treatment, while other growth retardant (GR) treatments had no effect on anthesis. Irradiance did not affect plant height at anthesis, but all GR treatments decreased height over control plants. Bract display and bract canopy display diameters declined as irradiance was decreased. Growth retardants did not affect individual bract display diameters, but all GR treatments except paclobutrazol reduced bract canopy display diameter. Plants grown under lower irradiance had fewer axillary buds develop, fewer bract displays per plant, and fewer cyathia per bract display. Cyathia abscission during a 30 day post-anthesis evaluation was not affected by treatment; however, plant leaf drop was linearly proportional to irradiance. All GR treatments increased leaf drop over controls, and the D+C treated plants had the highest leaf loss. Results indicate the irradiance and GR treatments during production can affect poinsettia crop timing, plant quality at maturity, and subsequent post-production performance.

Plants of Euphorbia pulcherrima Wind. `Glory' were grown under 13.4, 8.5, or 4.0 mol·m ⁻² ·day ⁻¹ and sprayed with water (control); 2500 mg·liter ⁻¹ daminozide + 1500 mg·liter ⁻¹ chlormequat chloride (D+C); 62.5 mg·liter ⁻¹ paclobutrazol; or 4, 8, 12 or 16 mg·liter ⁻¹ uniconazole to ascertain plant developmental and pest-production responses to the treatment combinations. Days to anthesis increased as irradiance was decreased. Anthesis was delayed by the D+C treatment, while other growth retardant (GR) treatments had no effect on anthesis. Irradiance did not affect plant height at anthesis, but all GR treatments decreased height over control plants. Bract display and bract canopy display diameters declined as irradiance was decreased. Growth retardants did not affect individual bract display diameters, but all GR treatments except paclobutrazol reduced bract canopy display diameter. Plants grown under lower irradiance had fewer axillary buds develop, fewer bract displays per plant, and fewer cyathia per bract display. Cyathia abscission during a 30 day post-anthesis evaluation was not affected by treatment; however, plant leaf drop was linearly proportional to irradiance. All GR treatments increased leaf drop over controls, and the D+C treated plants had the highest leaf loss. Results indicate the irradiance and GR treatments during production can affect poinsettia crop timing, plant quality at maturity, and subsequent post-production performance.

Equal doses of uniconazole were applied in differing spray volumes to plants of chrysanthemum ( Dendranthema grandiflora Tzvelev. ‘Ovaro’) to examine carrier volume effects on uniconazole efficacy. Plants received 204 ml water/m ² (controls) or 102, 204, 306, or 408 ml·m ⁻² of 40, 20, 13.3, or 10 mg uniconazole/liter, respectively. Treatments did not affect time from start of short days to bloom. Inflorescence display diameter was not affected by spray carrier volume, but was less for uniconazole-treated plants than for controls. No carrier volume effect on plant height was observed, but all uniconazole treatments resulted in plants shorter than controls. Plants of poinsettia ( Euphorbia pulcherrima Willd. ‘Annette Hegg Brilliant Diamond’, ‘Gutbier V-14 Glory’, ‘Eckespoint Celebrate’, and ‘Eckespoint Jingle Bells 3’) were sprayed with 204 ml water/m ² (controls) or 102, 204, 306, or 408 ml·m ⁻² of 20, 10, 6.7, or 5 mg uniconazole/liter, respectively. Treatments did not affect time from start of short days to anthesis or bract canopy diameter. Spray carrier volume did not affect plant height, but uniconazole-treated plants were shorter at anthesis than controls. The results obtained do not support the hypothesis that spray carrier volume affects the efficacy of uniconazole on chrysanthemums or poinsettias. Chemical name used: ( E )-1-( p -chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole).

Oriental hybrid lilies ( Lilium speciosum Thunb.) are grown as flowering potted plants or cut flowers (Ball, 1985). However, a major problem with oriental hybrid lilies grown as pot plants is plant height greater than desired for an appropriate aesthetic ratio (Sachs et al., 1976). Uniconazole is an effective chemical growth retardant on other lily species and has the advantage over ancymidol of high activity at very low dosages (Hol-comb and McDowell, 1987; Shumac et al., 1988). With the present work, we evaluated the effectiveness of uniconazole in controlling height of two L. speciosum hybrids and compared uniconazole with ancymidol.

Florists’ hydrangea is a woody perennial that has been adapted to potted plant production. A major factor in a hydrangea forcing program is height control. Currently, daminozide is used for reducing internode elongation in hydrangeas, but high concentrations (5000 to 7500 mg-liter ⁻¹ ) are sometimes needed to control vigorous cultivars such as ‘Rose Supreme’ (Jung, 1964; Ulery, 1978). Uniconazole has been shown to be an effective height-controlling agent at low concentrations for woody perennials, including Forsythia, Ligustrum, Pyracantha , and Rhododendron spp. (Knox and Norcini, 1987; Vaigro-Wolff and Warmund, 1987). Therefore, uniconazole was examined as a potential height-controlling chemical for florists’ hydrangea. Dormant plants of H. macrophylla ‘ Rose Supreme’ were defoliated and placed into 4C dark storage for 6 weeks beginning 2 Dec. 1987. On 13 Jan. 1988, the plants were removed from the cooler, potted one per 1.3-liter plastic container, and placed into a 26/15C (venting/night) greenhouse. The growth medium consisted of a 1 soil : 2 sphagnum peat : 2 perlite (by volume) mixture amended with 890 g treble superphosphate, 593 g KNO 3 , 593 g MgS0 4 , 4.75 kg ground dolomitic limestone, and 74 g Frit Industries Trace Elements No. 555 (Peters Fertilizer Products, W.R. Grace & Co., Fo-gelsville, Pa.) per cubic meter. The plants were fertilized at each watering with Ν and K, each at 200 mg-liter ⁻¹ , supplied from 367 mg NH 4 NO 3 /liter and 517 mg KNO 3 /liter, respectively. Fertilizer solution was maintained at 6.0 pH by injecting 75% (w/w) technical grade H 3 PO 4 into the system, supplying 37 mg P/liter at every watering. Each plant was pruned at potting, allowing only two shoots per plant to develop, and pots were spaced at 40 × 40 cm during forcing.

All growth retardant treatments (ancymidol, 50 mg·liter ⁻¹ , one or two sprays; uniconazole, 5, 10, or 15 mg·liter ⁻¹ , one or two sprays; 20 mg·liter ⁻¹ , one spray) reduced Easter lily ( Lilium longiflorum Thunb.) plant heights when compared to controls. Plant heights decreased linearly with increasing concentration of uniconazole for both one- and two-spray treatments. High concentrations of uniconazole delayed anthesis; ancymidol treatments did not. Individual corolla length was not affected by treatments. Treatments did not affect daughter bulb depletion or new daughter bulb growth. Total leaf area and leaf dry weight decreased as uniconazole concentration increased; ancymidol treatments did not affect leaf area, but did reduce leaf dry weight. Leaf total soluble carbohydrate decreased with increasing concentration of uniconazole. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine-methanol (ancymidol); (E)-1-(p-chlorophenyI)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole).