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David A. Gilbertz

Spray applications of 15 or 30 mg uniconazole or 30 or 60 mg paclobutrazol/liter (20 ml/1.5-liter pot) were sprayed 0, 2, or 4 weeks after pinching of Dendranthema × grandiflorum (Ramat.) Kitamura `Bright Golden Anne' plants. Plants were shorter the earlier growth regulators were applied. Plants were more responsive to uniconazole, requiring paclobutrazol at up to four times the uniconazole concentration to achieve the same height control. Time to flowering was also lengthened the earlier applications were made, up to 3 days compared to nontreated plants. Flower diameter was only minimally affected by the treatments. Chemical names used (2RS,3RS)-1-(4-chlorophenyl)-2-1,1-dimethylethyl)-(1H-1,2,4-triazol-1-yl)pentan-3-ol(-paclobutrazol);(E)-l(p-chlorophenyl) -4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol) (uniconazole).

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David A. Gilbertz

Spray applications of uniconazole (UC) or paclobutrazol (PB) were applied 0, 2, or 4 weeks after pinching Dendranthema grandiflora (Tzvelev). `Bright Golden Anne' cuttings planted 4 per 15 cm pot. Cuttings were controlled to 3 shoots each, averaging 5.4 and 14.9 cm at 2 and 4 weeks, respectively.

Final height was affected interactively by week of application and chemical treatment. Treatment at pinch caused less stem elongation than later treatments, probably due to persistence of PB and UC activity until flowering. At week 4, 67% of stem elongation had already occurred and, therefore, less retardation was possible. Of the 4 triazole treatments, PB at 30 mg 1-1 (20 ml per pot) applied at pinch produced heights similar to daminozide 5000 mg 1-1 applied at 2 weeks. PB at 60 mg 1-1 gave similar height control as UC 15 mg 1-1. UC 30 mg 1-1 treated plants were shortest regardless of treatment timing, averaging 16.9 cm applied week 2.

Other growth data was pooled for week of application and for chemical treatment since there was no interaction. Flowering was delayd 2 days and flower dry weight was reduced up to 26% by treatment at pinch compared to later treatments. Flower diameter was only minimally affected by treatments.

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David A Gilbertz

Seven to 9 cvs each of Begonia semperflorens, Tagetes erecta, T. patula, and Petunia hybrida (grandiflora and multiflora types) were sown into seedling trays. One to 3 weeks after transplanting to flats (75 cm3/cell), paclobutrazol (PB) was sprayed at concentrations of 10 (begonia), 60 (marigold) or 100 (petunia) mg liter-1 at a 200 ml m-2 rate. Uniconazole (UC) was applied at one-half the PB concentrations. Plant height was measured before planting in the field May 17 and monthly through July. Species were analyzed separately and generally, there were no cultivar by triazole interactions. During the greenhouse phase, the triazoles controlled height of both marigold species compared to control, but in July the PB and UC treated plants were 100 and 91%, respectively, of control plant height. Flowering was delayed up to 4 days for UC treated T. patula plants. Height of triazole-treated petunias was 60-67% of control height during the greenhouse phase and 84-95% after 2 months in the field. Begonia height was reduced by triazoles during both phases. After 2 months in the field, PB and UC treated begonias were 72 and 44%, respectively, of control plant height.

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Meriam G. Karlsson and David A. Gilbertz

The persistence of five growth regulators applied as spray or soil drenches was studied in vegetative Dendranthema X grandiflorum (Ramat) Kitamura `Bright Golden Anne' (BGA) and `Deep Luv' (DL). Spray treatments applied as 3 ml per plant consisted of 0.038 mg uniconazole (UC), 15 mg daminozide (DM), or 0.075 mg of either paclobutrazol (PB), flurprimidol (FP), or ancymidol (AC). Drenches of 0.025 mg UC, or 0.05 mg of either PB, FP or AC were applied at 60 ml per 500 cm3 pot. Growth (cm per week) in BGA was suppressed 60-73% compared to controls the week after application in all treatments except DM, which suppressed growth only 43%. By week 8, growth was similar to controls in all treatments except FP. With DL, all treatments suppressed growth 34-75% compared to controls the second week following application, except for no response to DM and PB sprays. Only plants treated with FP or UC drenches had not returned to similar growth as the control plants by week 10.