Efficacy of plant growth regulators on the growth of Argyranthemum frutescens 'Comet Pink'

The efficacy of pinching, daminozide, flurprimidol, uniconazole, or paclobutrazol + daminozide tank mix for plant height control, diameter control, and days to anthesis were investigated on Argyranthemum frutescens 'Comet Pink'. Plants were pinched 14 d after transplanting or treated 23 d after transplanting with foliar sprays of five concentrations from each plant growth regulator. Pinching reduced plant height but delayed anthesis compared to the control. Plant diameter was unaffected by pinching. None of the plant growth regulators affected time to anthesis. Daminozide was ineffective at controlling plant height, and plant diameter increased with 2500, 2500-applied twice, and 5000 mg(.)L(-1). Flurprimidol was effective at 50 to 125 mg(.)L(-1) for height control and at 125 mg(.)L(-1) for diameter control. However, phytotoxicity was observed at rates of 100 to 125 mg(.)L(-1). Uniconazole was effective at 40 and 80 mg(.)L(-1) with phytotoxicity evident at rates of 80 mg(.)L(-1). The paclobutrazol + daminozide tank mix did not affect plant height, but plants treated with 20 or 40 mg(.)L(-1) paclobutrazol plus 1250 mg(.)L(-1) daminozide had larger diameters than control plants. Flurprimidol at 50 to 75 mg(.)L(-1) or uniconazole at 40 mg(.)L(-1) were the most effective plant growth regulators for A. frutescens 'Comet Pink'.